The risk of illness or infection from public or shared recreational swimming pools and facilities is commonly associated with fecal contamination of the water.

The risk of illness or infection from public or shared recreational swimming pools and facilities is commonly associated with fecal contamination of the water.
The preparation of this volume has covered a period of over a decade and has involved the participation of numerous institutions and more than 60 experts from
20 countries worldwide. This is the first international point of reference to provide
comprehensive guidance for managing swimming pools and similar facilities so
that health benefits are maximized while negative public health impacts are
minimized.
This volume will be useful to a variety of different stakeholders with interests in
ensuring the safety of pools and similar environments, including national and local
authorities; facility owners, operators and designers (public, semi-public and
domestic facilities); special interest groups; public health professionals; scientists
and researchers; and facility users.
ISBN 92 4 154680 8
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS VOLUME 2. SWIMMING POOLS AND SIMILAR ENVIRONMENTS
Guidelines for Safe Recreational Water Environments Volume 2: Swimming Pools
and Similar Environments provides an authoritative referenced review and
assessment of the health hazards associated with recreational waters of this type;
their monitoring and assessment; and activities available for their control through
education of users, good design and construction, and good operation and
management. The Guidelines include both specific guideline values and good
practices. They address a wide range of types of hazard, including hazards leading
to drowning and injury, water quality, contamination of associated facilities and
air quality.
Guidelines for
safe recreational water
environments
VOLUME 2
SWIMMING POOLS AND
SIMILAR ENVIRONMENTS
WHO
Guidelines for safe
recreational water environments
VOLUME 2: SWIMMING POOLS AND SIMILAR
ENVIRONMENTS
WORLD HEALTH ORGANIZATION
2006
layout Safe Water.indd 1
24.2.2006 9:56:44
WHO Library Cataloguing-in-Publication Data
World Health Organization.
Guidelines for safe recreational water environments. Volume 2, Swimming pools
and similar environments.
1.Swimming pools — standards 2.Water quality — analysis 3.Drowning — prevention and
control 4.Wounds and injuries — prevention and control 5.Risk management 6.Reference
values 7.Guidelines I.Title II.Title: Swimming pools and similar environments.
ISBN 92 4 154680 8
(NLM classification: WA 820)
© World Health Organization 2006
All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health
Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 2476; fax: + 41 22 791 4857; email:
bookorders@who.int). Requests for permission to reproduce or translate WHO publications – whether for sale or
for noncommercial distribution – should be addressed to WHO Press, at the above address (fax: +41 22 791 4806;
email: permissions@who.int).
The designations employed and the presentation of the material in this publication do not imply the expression of
any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country,
territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines
on maps represent approximate border lines for which there may not yet be full agreement.
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or
recommended by the World Health Organization in preference to others of a similar nature that are not mentioned.
Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.
All reasonable precautions have been taken by the World Health Organization to verify the information contained in
this publication. However, the published material is being distributed without warranty of any kind, either express
or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall
the World Health Organization be liable for damages arising from its use.
Design by minimum graphics
Typeset by Strategic communications SA, Geneva
Printed in France
layout Safe Water.indd 2
24.2.2006 9:56:45
Contents
List of acronyms and abbreviations
Preface
Acknowledgements
Executive summary
CHAPTER 1. INTRODUCTION
1.1
1.2
1.3
1.4
1.4.1
1.4.2
1.4.3
1.5
1.6
1.7
General considerations
Types of pools
Types of users
Hazard and risk
Types of hazard encountered
Assessment of hazard and risk
Degree of water contact
Measures to reduce risks
Nature of the guidelines
References
vi
viii
x
xiii
1
1
3
4
5
5
6
8
9
9
10
CHAPTER 2. DROWNING AND INJURY PREVENTION
12
2.1
2.1.1
2.1.2
2.2
2.2.1
2.2.2
2.3
2.4
2.5
2.6
2.7
2.8
12
14
15
16
18
18
19
19
20
20
21
22
Drowning
Contributory factors
Preventive and management actions
Spinal injury
Contributory factors
Preventive and management actions
Brain and head injuries
Fractures, dislocations, other impact injuries, cuts and lesions
Disembowelment
Hazards associated with temperature extremes
Injuries associated with ‘feature pools’
References
CHAPTER 3. MICROBIAL HAZARDS
26
3.1
Faecally-derived viruses
3.1.1 Hazard identification
3.1.2 Outbreaks of viral illness associated with pools
28
28
28
iii
layout Safe Water.indd 3
24.2.2006 9:56:45
3.1.3
3.1.4
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.5
3.5.1
3.5.2
3.6
3.6.1
3.6.2
3.6.3
3.7
3.7.1
3.8
iv
layout Safe Water.indd 4
Risk assessment
Risk management
Faecally-derived bacteria
Hazard identification
Outbreaks of bacterial illness associated with pools
Risk assessment
Risk management
Faecally-derived protozoa
Hazard identification
Outbreaks of protozoan illness associated with pools
Risk assessment
Risk management
Non-faecally-derived bacteria
Legionella spp.
Pseudomonas aeruginosa
Mycobacterium spp.
Staphylococcus aureus
Leptospira interrogans sensu lato
Non-faecally-derived viruses
Molluscipoxvirus
Papillomavirus
Non-faecally-derived protozoa
Naegleria fowleri
Acanthamoeba spp.
Plasmodium spp.
Non-faecally-derived fungi
Trichophyton spp. and Epidermophyton floccosum
References
31
32
33
33
33
34
35
35
35
35
38
39
40
40
43
45
46
47
48
48
49
49
50
51
52
52
52
53
CHAPTER 4. CHEMICAL HAZARDS
60
4.1
4.1.1
4.1.2
4.1.3
4.2
4.3
4.4
4.4.1
4.4.2
4.4.3
4.5
4.5.1
4.5.2
4.6
4.7
60
61
61
61
62
62
63
63
66
66
66
68
71
76
76
Exposure
Ingestion
Inhalation
Dermal contact
Source water-derived chemicals
Bather-derived chemicals
Management-derived chemicals
Disinfectants
pH correction
Coagulants
Disinfection by-products (DBP)
Exposure to disinfection by-products
Risks associated with disinfection by-products
Risks associated with plant and equipment malfunction
References
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:45
CHAPTER 5. MANAGING WATER AND AIR QUALITY
80
5.1
Pre-swim hygiene
5.2
Coagulation
5.3
Disinfection
5.3.1 Choosing a disinfectant
5.3.2 Characteristics of various disinfectants
5.3.3 Disinfection by-products (DBP)
5.3.4 Disinfectant dosing
5.4
Filtration
5.4.1 Filter types
5.4.2 Turbidity measurement
5.5
Dilution
5.6
Circulation and hydraulics
5.7
Bathing load
5.8
Accidental release of faeces or vomit into pools
5.9
Air quality
5.10
Monitoring
5.10.1 Turbidity
5.10.2 Residual disinfectant level
5.10.3 pH
5.10.4 Oxidation–reduction potential (ORP)
5.10.5 Microbial quality
5.10.6 Other operational parameters
5.11
Cleaning
5.12
References
81
82
82
82
83
87
87
88
88
89
90
90
91
92
93
94
94
94
95
96
99
98
98
99
CHAPTER 6. GUIDELINE IMPLEMENTATION
100
6.1
6.2
6.2.1
6.2.2
6.3
6.3.1
6.3.2
6.4
6.4.1
6.4.2
6.5
6.6
100
103
103
105
105
108
109
110
111
112
113
113
Design and construction
Operation and management
Pool safety plan
Lifeguards
Public education and information
Signage
Education
Regulatory requirements
Regulations and compliance
Registration and certification schemes
Conclusions
References
APPENDIX 1. LIFEGUARDS
CONTENTS
layout Safe Water.indd 5
114
v
24.2.2006 9:56:46
List of acronyms and abbreviations
AFR
AIDS
BCDMH
BDCM
cfu
CPR
CPSC
DBAA
DBAN
DBCM
DBP
DCAA
DCAN
DMH
FAO
GAE
HAA
HIV
HPC
HUS
HVAC
ID50
ILSF
ISO
JECFA
LOAEL
MBAA
MCAA
NOAEL
NOEL
NTU
ORP
PAM
pfu
QMRA
TCAA
accidental faecal release
acquired immunodeficiency syndrome
bromochlorodimethylhydantoin
bromodichloromethane
colony-forming unit
cardiopulmonary resuscitation
Consumer Product Safety Commission (USA)
dibromoacetic acid
dibromoacetonitrile
dibromochloromethane
disinfection by-products
dichloroacetic acid
dichloroacetonitrile
dimethylhydantoin
Food and Agriculture Organization of the United Nations
granulomatous amoebic encephalitis
haloacetic acid
human immunodeficiency virus
heterotrophic plate count
haemolytic uraemic syndrome
heating, ventilation and air conditioning
infectious dose for 50% of the population
International Life Saving Federation
International Organization for Standardization
Joint FAO/WHO Expert Committee on Food Additives
and Contaminants
lowest-observed-adverse-effect level
monobromoacetic acid
monochloroacetic acid
no-observed-adverse-effect level
no-observed-effect level
nephelometric turbidity unit
oxidation–reduction potential
primary amoebic meningoencephalitis
plaque-forming unit
quantitative microbiological risk assessment
trichloroacetic acid
vi
layout Safe Water.indd 6
24.2.2006 9:56:46
TCAN
TDI
TDS
THM
TOC
UFF
UV
WHO
trichloroacetonitrile
tolerable daily intake
total dissolved solids
trihalomethane
total organic carbon
ultrafine filter
ultraviolet
World Health Organization
LIST OF ACRONYMS AND ABBREVIATIONS
layout Safe Water.indd 7
vii
24.2.2006 9:56:46
Preface
T
he World Health Organization (WHO) has been concerned with health aspects of the
management of water resources for many years and publishes various documents
concerning the safety of the water environment and its importance for health. These
include a number of normative “guidelines” documents, such as the Guidelines for
Drinking-water Quality and the Guidelines for the Safe Use of Wastewater, Excreta and
Greywater. Documents of this type are intended to provide a basis for standard setting.
They represent a consensus view among experts on the risk to health represented by
various media and activities and on the effectiveness of control measures in protecting
health. They are based on critical review of the available evidence. Wherever possible
and appropriate, such guideline documents also describe the principal characteristics
of the monitoring and assessment of the safety of the medium under consideration as
well as the principal factors affecting decisions to be made in developing strategies for
the control of the health hazards concerned.
The Guidelines for Safe Recreational Water Environments are published in two volumes:
• Volume 1: Coastal and Fresh Waters provides an authoritative referenced review and
assessment of the various health hazards encountered during recreational use
of coastal and freshwater environments. It includes the derivation of guideline
values or conditions and explains the basis for the decision to derive or not to
derive them. It addresses a wide range of types of hazard, including hazards
leading to drowning and injury, water quality, exposure to heat, cold and sunlight, and dangerous aquatic organisms; and provides background information
on the different types of recreational water activity (swimming, surfing, etc.)
to enable informed readers to interpret the Guidelines in light of local and
regional circumstances. With regard to water quality, separate chapters address
microbial hazards, freshwater algae, marine algae and chemical aspects. The volume describes prevention and management options for responding to identified
hazards.
• Volume 2: Swimming Pools and Similar Recreational Water Environments provides
an authoritative referenced review and assessment of the health hazards associated with recreational waters of this type; their monitoring and assessment; and
activities available for their control through education of users, good design and
construction, and good operation and management. The Guidelines include
both specific guideline values and good practices. They address a wide range of
types of hazard, including hazards leading to drowning and injury, water quality, contamination of associated facilities and air quality.
viii
layout Safe Water.indd 8
24.2.2006 9:56:46
The preparation of this volume of Guidelines for Safe Recreational Water Environments has covered a period of over a decade and has involved the participation of
numerous institutions and more than 60 experts from 20 countries worldwide. The
work of the individuals concerned (see Acknowledgements) was central to the completion of the work and is much appreciated.
PREFACE
layout Safe Water.indd 9
ix
24.2.2006 9:56:46
Acknowledgements
T
he assistance of the following persons in the development of the Guidelines for
Safe Recreational Water Environments, Volume 2: Swimming Pools and Similar
Environments, either in contribution of text or through provision of comments and
constructive criticism, is appreciated:
Houssain Abouzaid, WHO Regional Office for the Eastern Mediterranean, Cairo, Egypt
Gabrielle Aggazzotti, University of Modena, Modena, Italy
Jamie Bartram, WHO, Geneva, Switzerland
Joost Bierens, VU University Medical Centre, Amsterdam, The Netherlands
Lucia Bonadonna, Istituto Superiore di Sanità, Rome, Italy
Christine Branche, National Center for Injury Prevention and Control, US Centers
for Disease Control and Prevention, Atlanta, GA, USA
B. Chris Brewster, International Life Saving Federation, San Diego, CA, USA
Teresa Brooks, Health Canada, Ottawa, Canada
Marilyn L. Browne, Bureau of Environmental and Occupational Epidemiology, New
York State Department of Health, Troy, NY, USA
Rudy Calders, Provinciaal Instituut voor Hygienne, Antwerp, Belgium
Richard Carr, WHO, Geneva, Switzerland
Rodney Cartwright, Microdiagnostics, Guildford, UK
Maurizio Cavalieri, Azienda Comunale Energia e Ambiente (ACEA), Rome, Italy
Paul C. Chrostowski, CPF Associates, Takoma Park, MD, USA
Joseph Cotruvo, NSF International, Washington, DC, USA
Carvin DiGiovanni, National Spa and Pool Institute, Alexandria, VA, USA
Alfred P. Dufour, National Exposure Research Laboratory, US Environmental Protection Agency, Cincinnati, OH, USA
Takuro Endo, National Institute of Infectious Diseases, Tokyo, Japan
Lothar Erdinger, Institute for Hygiene, University of Heidelberg, Germany
G. Fantuzzi, University of Modena, Modena, Italy
Norman Farmer, International Life Saving Federation, Melbourne, Australia
John Fawell, Independent Consultant, Flackwell Heath, UK
Lorna Fewtrell, Centre for Research into Environment and Health (CREH), University of Wales, Aberystwyth, UK
Maria Jose Figueras, University Rovira and Virgili, Tarragona-Reus, Spain
Willie Grabow, University of Pretoria, Pretoria, South Africa
Brian Guthrie, Pool Water Treatment Advisory Group, Norfolk, UK
Rudy Hartskeerl, Royal Tropical Institute (KIT), Amsterdam, The Netherlands
Christiane Höller, Bavarian Health and Food Safety Authority, Oberschleißheim,
Germany
x
layout Safe Water.indd 10
24.2.2006 9:56:46
Paul Hunter, University of East Anglia, Norwich, UK
Owen Hydes, Independent Consultant, Mannings Heath, UK
Pranav Joshi, National Environment Agency, Singapore
Mihaly Kadar, National Institute of Hygiene, Budapest, Hungary
Simon Kilvington, Department of Microbiology and Immunology, University of
Leicester, Leicester, UK
Tom Kuechler, Occidental Chemical Corporation, Sanget, IL, USA
Athena Mavridou, Technological Educational Institution of Athens, Athens, Greece
Charles Mbogo, Kenya Medical Research Institute, Kilifi, Kenya
Douglas B. McGregor (formerly of International Programme on Chemical Safety),
Independent Consultant, Lyon, France
Art Mittelstaedt, Recreational Safety Institute, New York, NY, USA
Eric Mood, School of Medicine, Yale University, New Haven, CT, USA
Phil Penny, Independent Consultant, Taunton, UK
Kathy Pond, Robens Centre for Public and Environmental Health, University of Surrey,
Guildford, Surrey, UK (formerly of WHO European Centre for Environment and
Health, Rome, Italy)
Terry Price, TP Pool Water Treatment Services Ltd., Broxbourne, UK
M. Rayer, NSF International, Ann Arbor, MI, USA
Gareth Rees, Askham Bryan College, York, UK
R.G. Rice, RICE International Consulting Enterprises, Ashton, MD, USA
Ralph Riley, Institute of Sport and Recreation Management, Loughborough, UK
Will Robertson, Health Canada, Ottawa, Canada
Henry Salas, Pan American Center for Sanitary Engineering and Environmental Science,
Lima, Peru
Ian Scott, WHO, Geneva, Switzerland
Geoff Shute, Tintometer Ltd., Salisbury, UK
Jeff Sloan, Chlorine Chemistry Council, Arlington, VA, USA
Jeff Soller, National Center for Environmental Assessment, US Environmental Protection Agency, Washington, DC, USA
Thor-Axel Stenström, Swedish Institute for Infectious Disease Control, Stockholm,
Sweden
Paul Stevenson, Stevenson & Associates Pty Ltd., Sydney, Australia
Ernst Stottmeister, Federal Environment Agency (UBA), Bad Elster, Germany
Susanne Surman-Lee, Health Protection Agency, London, UK
Laura Tew, Arch Chemicals, Charleston, TN, USA
Carolyn Vickers, WHO, Geneva, Switzerland
Albrecht Wiedenmann, Baden-Württemberg State Health Office, Stuttgart, Germany
Adam Wooler, Royal National Lifeboat Institution, Saltash, Cornwell, UK (formerly
of the Surf Life-Saving Association of Great Britain, Plymouth, Devon, UK)
Peter Wyn-Jones, University of Wales, Aberystwyth, UK
The preparation of these Guidelines would not have been possible without the
generous support of the following, which is gratefully acknowledged: the European
Commission; the States of Jersey, United Kingdom; the Department of the Environment, Transport and the Regions of the United Kingdom; the Ministry of Health of
Germany; the Ministry of Environment of Germany; the Ministry of Health of Italy;
ACKNOWLEDGEMENTS
layout Safe Water.indd 11
xi
24.2.2006 9:56:47
the Swedish International Development Cooperation Agency; and the United States
Environmental Protection Agency.
Thanks are also due to Lorna Fewtrell for editing the complete text of the
Guidelines and overseeing the review process and finalization of the Guidelines,
Marla Sheffer for editing the initial draft and Grazia Motturi, Penny Ward, Windy
Gancayo-Prohom and Evelyn Kortum-Margot for providing secretarial and administrative support.
xii
layout Safe Water.indd 12
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:47
Executive summary
T
his volume of the Guidelines for Safe Recreational Water Environments describes the
present state of knowledge regarding the impact of the recreational use of swimming pools and similar environments upon the health of users – specifically drowning
and injury, microbial contamination and exposure to chemicals. Control and monitoring of the hazards associated with these environments are discussed.
The primary aim of the Guidelines is the protection of public health. The purpose
of the Guidelines is to ensure that swimming pools and similar recreational water
facilities are operated as safely as possible in order that the largest possible population
gets the maximum possible benefit and not to deter the use of these recreational water
environments.
The Guidelines are intended to be used as the basis for the development of approaches to controlling the hazards that may be encountered in recreational water
environments. The information provided is generally applicable to pools supplied
with fresh, marine or thermal water, whether they are indoors or outdoors; public,
semi-public or domestic; supervised or unsupervised. Information also relates to public, semi-public and domestic hot tubs (which, for the purposes of these Guidelines, is
the term used to encompass a variety of facilities that are designed for sitting in, contain treated water usually above 32 °C, are often aerated and are not drained, cleaned
and refilled for each user) and natural spas (facilities using thermal and/or mineral
water). Although bathing houses, such as hammams, are not specifically covered, the
principles outlined in the Guidelines should also be generally applicable to these environments. The preferred approaches adopted by national or local authorities towards
implementation of guideline values and conditions may vary between these types of
environment.
A guideline can be:
• a level of management;
• a concentration of a constituent that does not represent a significant risk to the
health of members of significant user groups;
• a condition under which exposures with a significant risk are unlikely to occur;
or
• a combination of the last two.
When a guideline is exceeded, this should be a signal to investigate the cause of
the failure and identify the likelihood of future failure, to liaise with the authority
responsible for public health to determine whether immediate action should be taken
to reduce exposure to the hazard, and to determine whether measures should be put
in place to prevent or reduce exposure under similar conditions in the future.
xiii
layout Safe Water.indd 13
24.2.2006 9:56:47
Drowning and injury prevention
Drowning, which is defined in these Guidelines as death arising from impairment
of respiratory function as a result of immersion in liquid, is a major cause of death
worldwide. Near-drowning is also a serious problem, as it may have lifelong effects.
The recovery rate from near-drowning may be lower among young children than
among teenagers and adults. Studies show that the prognosis for survival depends
more on the effectiveness of the initial rescue and resuscitation than on the quality
of subsequent hospital care. Most studies of accidental drowning have focused on
children, and in some countries drowning is the leading cause of injury deaths among
younger age groups. It has been suggested that in terms of swimming pools and similar environments most drownings occur in domestic pools and hot tubs, many while
the child’s supervisor assumed the child was safely indoors.
In swimming pools and similar environments, alcohol consumption is one of the
most frequently reported contributory factors associated with drownings and neardrownings for adults, whereas lapses in parental supervision are most frequently cited
for incidents involving children. Also of concern is the danger of drownings and
near-drownings due to inlets and outlets where the suction is strong enough to cause
entrapment of body parts or hair, causing the victim’s head to be held under water.
Few preventive measures for drowning and near-drowning have been evaluated,
although installation of isolation fencing around outdoor pools has been shown by
some studies to decrease the number of pool immersion injuries by more than 50%.
Pool fences around domestic pools should have a self-closing and self-latching gate
and should isolate the pool. Barrier fencing should be at least 1.2 m high and have no
hand- or footholds that could enable a young child to climb it. Fence slats should be
no more than 10 cm apart. Above-ground pools should have steps or ladders leading
to the pool that can be secured and locked to prevent access when the pool is not in
use. For domestic or outdoor hot tubs, it is recommended that locked safety covers be
used when the hot tub is not in use.
Preventive measures for hair and body entrapment in pools and similar environments include the use of grilles on drain gates that prevent hair entrapment, dual
drains, an accessible and/or pressure-activated emergency shut-off for the pump and
the wearing of bathing caps. Warnings displayed in the form of clear and simple signs
as well as water safety instruction and adult supervision all may have value as preventive actions.
Of sports-related spinal cord injuries, the majority appear to be associated with
diving. Injuries in diving incidents are almost exclusively located in the cervical vertebrae, resulting in quadriplegia (paralysis affecting all four limbs) or paraplegia (paralysis of both legs). Data suggest that diving into the upslope of a pool bottom or
into the shallow portion of the pool is the most common cause of spinal injuries in
pools. Alcohol consumption may contribute significantly to the frequency of injury.
Education and raising awareness appear to offer the most potential for diving injury
prevention.
Other injuries associated with the use of swimming pools and similar environments
include brain and head injuries and arm, hand, leg and foot/toe injuries. Expert opinion suggests that the latter are common and generally go unreported. Causes include
slippery decks, uncovered drains, reckless water entry, running on decks, tripping
on swimming aids left on the poolside and stepping on glass (from broken bottles).
xiv
layout Safe Water.indd 14
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:47
Maintenance of surfaces (including appropriate waste disposal), supervision of pool
users, providing appropriate warnings, ensuring good underwater visibility and pool
safety education are among the actions that can reduce these incidents.
High temperatures in hot tubs, for example, can cause drowsiness, which may
lead to loss of consciousness or to heat stroke and death, and it is recommended that
water temperatures in hot tubs be kept below 40 °C. Exposure to low temperatures in
plunge pools, which are used in conjunction with saunas or steam baths, may result in
slowed heart beat, hypothermia, impaired coordination, loss of control of breathing,
muscle cramps and loss of consciousness. Temperature extremes should be avoided
by users with medical problems, pregnant women and young children. Educational
displays and warning signs, warnings from pool staff and regulations on time limits
for use can reduce these adverse outcomes.
Microbial hazards
The risk of illness or infection associated with swimming pools and similar recreational water environments is primarily associated with faecal contamination of the water.
This may be due to faeces released by the bathers or contaminated source water or, in
the case of outdoor pools, may be the result of direct animal contamination (e.g. from
birds and rodents). Many of the outbreaks related to pools and similar environments
have occurred because disinfection was not applied or was inadequate. Non-faecal
human shedding into the pool water or surrounding area is also a potential source of
pathogenic organisms.
Swimming pool-related outbreaks of illness are relatively infrequent, but have been
linked to viruses, bacteria, protozoa and fungi. Viral outbreaks are most often attributed to adenovirus, although hepatitis A, norovirus and echovirus have also been
implicated in pool-related disease outbreaks. It should be borne in mind that the
evidence linking viral outbreaks to a pool is generally circumstantial, and the causative
viruses have rarely been isolated from the water.
Shigella and Escherichia coli O157 are two related bacteria that have been linked
to outbreaks of illness associated with swimming in pools. Symptoms of E. coli O157
infection include bloody diarrhoea (haemorrhagic colitis) and haemolytic uraemic
syndrome (HUS), as well as vomiting and fever in more severe cases. HUS, characterized by haemolytic anaemia and acute renal failure, occurs most frequently in infants,
young children and elderly people. Symptoms associated with shigellosis include diarrhoea, fever and nausea.
The risk of illness in swimming pools associated with faecally-derived protozoa
mainly involves two parasites: Giardia and Cryptosporidium. These two organisms
have a cyst or oocyst form that is highly resistant to both environmental stress and
disinfectants. They also both have high infectivity and are shed in high densities by
infected individuals. Giardiasis is characterized by diarrhoea, cramps, foul-smelling
stools, loss of appetite, fatigue and vomiting, whereas symptoms of cryptosporidiosis
include diarrhoea, vomiting, fever and abdominal cramps.
The control of viruses and bacteria in swimming pool water is usually accomplished by appropriate treatment, including filtration and the proper application of
chlorine or other disinfectants. Episodes of gross contamination of pool water due to
an accidental faecal release, however, cannot all be effectively controlled by normal
treatment and disinfectant levels. Where pools or spas are not disinfected, accidental
EXECUTIVE SUMMARY
layout Safe Water.indd 15
xv
24.2.2006 9:56:47
faecal releases present an even greater problem. The only approach to maintaining
public health protection under conditions of an accidental faecal release is to prohibit
the use of the pool until the potential contaminants are inactivated.
Pool operators can help prevent faecal contamination of pools by encouraging preswim showering and toilet use and, where possible, confining young children to pools
small enough to drain in the event of an accidental faecal release. It is recommended
that people with gastroenteritis not use public or semi-public facilities while ill or for
at least a week after their illness.
As well as pathogenic enteric organisms, a number of infectious non-enteric organisms may be transferred through pool water and the surrounding environment via
human shedding. Infected users can directly contaminate pool waters and the surfaces
of objects or materials at a facility with primary pathogens (notably viruses or fungi)
in sufficient numbers to lead to skin and other infections in users who subsequently
come in contact with the contaminated water or surfaces. Opportunistic pathogens
(notably bacteria) can also be shed from users and be transmitted via both surfaces
and contaminated water. In addition, certain free-living aquatic bacteria and amoebae
can grow in pool, hot tub or natural spa waters, in pool or hot tub components or
facilities (including heating, ventilation and air-conditioning systems) or on other wet
surfaces within the facility to a point at which they may cause a variety of respiratory,
dermal or central nervous system infections or diseases.
Most of the legionellosis, an often serious infection caused by Legionella species,
associated with recreational water use has been associated with public and semi-public
hot tubs and natural spas. Natural spas (especially thermal water) and hot tub water
and the associated equipment create an ideal habitat (warm, nutrient-containing aerobic water) for the selection and proliferation of Legionella. Pseudomonas aeruginosa
is also frequently present in hot tubs, as it is able to withstand high temperatures and
disinfectants and to grow rapidly in waters supplied with nutrients from users. In hot
tubs, the primary health effect associated with the presence of P. aeruginosa is folliculitis, an infection of the hair follicles that may result in a pustular rash.
It is less easy to control the growth of Legionella spp. and P. aeruginosa in hot tubs
than in pools, as the design and operation of hot tubs can make it difficult to achieve
adequate residual disinfection levels in these facilities. Thus, in public and semi-public
facilities, frequent monitoring and adjustment of pH and disinfectant levels are essential, as are programmed ‘rest periods’ to allow disinfectant levels to ‘recover’. In addition, facility operators should require users to shower before entering the water and
control the number of users and the duration of their exposure. Thorough cleaning of
the area surrounding the hot tub on a frequent basis (e.g. daily), complete draining and
cleaning of the hot tub and pipework on at least a weekly basis, frequent backwashing
and filter inspection and good ventilation are all recommended control measures.
Molluscipoxvirus (which causes molluscum contagiosum), papillomavirus (which
causes benign cutaneous tumours – verrucae), Epidermophyton floccosum and various
species of fungi in the genus Trichophyton (which cause superficial fungal infections
of the hair, fingernails or skin) are spread by direct person-to-person contact or indirectly, through physical contact with contaminated surfaces. As the primary source of
these viruses and fungi in swimming pools and similar environments is infected bathers, the most important means of controlling the spread of the infections is educating
the public about the diseases, including the importance of limiting contact between
xvi
layout Safe Water.indd 16
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:48
infected and non-infected people and medical treatment. Thorough frequent cleaning and disinfection of surfaces in facilities that are prone to contamination can also
reduce the spread of the diseases.
Chemical hazards
Chemicals found in swimming pool water can be derived from a number of sources,
namely the source water, deliberate additions such as disinfectants and pool users
themselves (these include sweat, urine, soap residues, cosmetics and suntan oil).
There are three main routes of exposure to chemicals in swimming pools and similar environments: direct ingestion of the water, inhalation of volatile or aerosolized
solutes and dermal contact and absorption through the skin. The amount of water
ingested by swimmers and bathers will depend upon a range of factors, including
experience, age, skill and type of activity. Experimental evidence suggests that water
intake varies according to age and sex, with adult women ingesting the least and male
children ingesting the most. Swimmers inhale from the atmosphere just above the
water’s surface, and the volume of air inhaled is a function of the intensity of effort
and time. Inhalation exposure will be largely associated with volatile substances that
are lost from the water surface, but will also include some inhalation of aerosols,
within a hot tub (for example) or where there is significant splashing. Dermal exposure depends upon the period of contact with the water, water temperature and the
concentration of the chemical.
The principal management-derived chemicals are disinfectants, added to minimize
the risk to pool users from microbial contaminants. Coagulants may be added as part
of the water treatment process to enhance the removal of dissolved, colloidal or suspended material. Acids and alkalis may also be added to the water in order to maintain an appropriate pH for optimal water treatment and also the comfort of bathers.
The chemical disinfectants that are used most frequently include chlorine (as a
gas, hypochlorite or, generally for outdoor pools, chlorinated isocyanurates), chlorine
dioxide, bromochlorodimethylhydantoin (BCDMH), ozone and ultraviolet (UV)
radiation (with ozone and UV usually being used in combination with a chlorineor bromine-based disinfectant). Practice varies widely around the world, as do the
levels of chemicals that are currently considered to be acceptable in order to achieve
adequate disinfection while minimizing user discomfort. It is recommended that acceptable levels of free chlorine continue to be set at the local level, but in public and
semi-public pools these should not exceed 3 mg/l and in public and semi-public hot
tubs should not exceed 5 mg/l. It is recommended that total bromine does not exceed
4 mg/l in public and semi-public pools and 5 mg/l in hot tubs. Where chlorinated
isocyanurates are used, levels of cyanuric acid in pool water should not exceed 100
mg/l. Where ozone is used, an air quality guideline of 0.12 mg/m3 is recommended
in order to protect bathers and staff working in the pool building.
A number of disinfectants can react with other chemicals in the water to give rise
to unwanted by-products, known as disinfection by-products. Most is known about
the by-products that result from the reaction of chlorine with humic and fulvic acids,
but there is evidence from model studies with amino acids that other organic substances will also give rise to a similar range of by-products. Although there is potentially a large number of by-products, the substances produced in the greatest quantities are trihalomethanes, of which chloroform is generally present in the greatest
EXECUTIVE SUMMARY
layout Safe Water.indd 17
xvii
24.2.2006 9:56:48
concentrations, and the haloacetic acids, of which di- and trichloroacetic acid are
generally present in the greatest concentrations. Both chlorine and bromine will react
with ammonia in the water (resulting from the presence of urine) to form chloramines
(monochloramine, dichloramine and nitrogen trichloride) and bromamines.
Trihalomethanes have been considered more than other chlorination by-products,
reflecting the level of available information. Concentrations vary as a consequence
of the concentration of precursor compounds, chlorine dose, temperature and pH.
Trihalomethanes are volatile in nature and can be lost from the surface of the water,
so they are also found in the air above the pool.
The guideline values in the WHO Guidelines for Drinking-water Quality can be
used to screen for potential risks arising from swimming pools and similar environments, while making appropriate allowance for the much lower quantities of water
ingested, shorter exposure periods and non-ingestion exposure. Although there are
data to indicate that the concentrations of chlorination by-products in swimming
pools and similar environments may exceed the concentrations proposed by WHO
for drinking-water, the evidence indicates that for reasonably well managed pools,
concentrations less than the drinking-water guideline values can be consistently
achieved. The risks from exposure to chlorination by-products in reasonably well
managed swimming pools would be considered to be small and must be set against
the benefits of aerobic exercise and the risks of microbial disease in the absence of
disinfection. Nevertheless, competitive swimmers and pool attendants can experience
substantial exposure to volatile disinfection by-products via inhalation and dermal
absorption. The chloramines and bromamines, particularly nitrogen trichloride and
nitrogen tribromide, which are both volatile, can give rise to significant eye and
respiratory irritation in swimmers and pool attendants. The provisional guideline
value for chlorine species, expressed as nitrogen trichloride, in the atmosphere of
swimming pools and similar environments is 0.5 mg/m3.
Managing water and air quality
The primary water and air quality health challenges are, in typical order of public
health priority, controlling clarity to minimize injury hazard, controlling water quality to prevent the transmission of infectious disease and controlling potential hazards
from disinfection by-products. All of these challenges can be met through the combination of the following factors: treatment (to remove particulates, pollutants and
microorganisms), including disinfection and filtration; pool hydraulics (to ensure effective distribution of disinfectant throughout the pool and removal of contaminated
water); addition of fresh water at frequent intervals (to dilute substances that cannot
be removed from the water by treatment); cleaning (to remove biofilms from surfaces,
sediments from the pool floor and particulates adsorbed to filter materials); and adequate ventilation of indoor facilities.
Pre-swim showering will help to remove traces of sweat, urine, faecal matter, cosmetics, suntan oil and other potential water contaminants. Where pool users normally shower before swimming, pool water is cleaner, easier to disinfect with smaller
amounts of chemicals and thus more pleasant to swim in. All users should also be
encouraged to use the toilets before bathing to minimize urination in the pool and
accidental faecal releases.
xviii
layout Safe Water.indd 18
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:49
Disinfection is part of the treatment process whereby pathogenic microorganisms
are inactivated by chemical (e.g. chlorination) or physical (e.g. UV radiation) means
such that they represent no significant risk of infection. Circulating pool water is
disinfected during the treatment process, and the entire water body is disinfected by
the application of a residual disinfectant (chlorine- or bromine-based), which partially
inactivates agents added to the pool by bathers. The choice of disinfectant depends
upon a number of factors, including safety, compatibility with the source water, type,
size and location of the pool, bathing load and the operation of the pool.
The concentration of disinfection by-products can be controlled to a significant
extent by minimizing the introduction of precursors though source water selection,
good bather hygienic practices (e.g. pre-swim showering), maximizing their removal
by well managed pool water treatment and replacement of water by the addition of
fresh supplies (i.e. dilution of chemicals that cannot be removed). It is inevitable,
however, that some volatile disinfection by-products (such as chloroform and nitrogen
trichloride) may be produced in the pool water and escape into the air. This hazard
can be managed to some extent through good ventilation of indoor pool buildings.
Filtration is important in ensuring a safe pool. If filtration is poor, water clarity will decline and drowning risks increase. Disinfection will also be compromised,
as particles associated with turbidity can surround microorganisms and shield them
from the action of disinfectants. Particulate removal through coagulation and filtration is important for removing Cryptosporidium oocysts and Giardia cysts and some
other protozoa that are resistant to chemical disinfection. For identifying bodies at
the bottom of the pool, a universal turbidity value is not considered appropriate, as
much depends on the characteristics of the specific pool. Individual standards should
be developed, based on risk assessment at each pool, but it is recommended that,
as a minimum, it should be possible to see a small child at the bottom of the pool
from the lifeguard position while the water surface is in movement. In terms of effective disinfection, a useful, but not absolute, upper-limit guideline for turbidity is 0.5
nephelometric turbidity units.
Coagulation, filtration and disinfection will not remove all pollutants. Swimming
pool design should enable the dilution of pool water with fresh water. Dilution limits
the build-up of pollutants from bathers (e.g. constituents of sweat and urine), disinfection by-products and various other dissolved chemicals. Pool operators should replace
pool water as a regular part of their water treatment regime. As a general rule, the addition of fresh water to disinfected pools should not be less than 30 litres per bather.
Good circulation and hydraulics in the pool ensure that the whole pool is adequately served by filtered, disinfected water. Treated water must get to all parts of
the pool, and polluted water must be removed – especially from areas most used and
most polluted by bathers. It is recommended that 75–80% be taken from the surface
(where the pollution is greatest), with the remainder taken from the bottom of the
pool.
Accidental faecal releases may occur relatively frequently, although it is likely that
most go undetected. A pool operator faced with an accidental faecal release or vomit
in the pool water must act immediately. If the faecal release is solid, it should be
retrieved quickly and discarded appropriately. The scoop used to retrieve the faeces
should be washed carefully and disinfected after use. If residual disinfectant levels are
satisfactory, no further action is necessary. Where the stool is runny (diarrhoea) or if
EXECUTIVE SUMMARY
layout Safe Water.indd 19
xix
24.2.2006 9:56:49
there is vomit, the situation is likely to be more hazardous. The safest course of action
in small pools or hot tubs is to evacuate users, drain, clean and refill. Where draining
is not possible, the pool should be cleared of people immediately; as much of the material as possible should be collected, removed and disposed of to waste; disinfectant
levels should be maintained at the top of the recommended range or shock dosing
used; using a coagulant (if appropriate), the water should be filtered for six turnover
cycles; and the filter should be backwashed.
In indoor facilities, it is important to manage air quality as well as water quality in
swimming pools and similar recreational water environments. This is important not
only for staff and user health, but also for their comfort and to avoid negative impacts
on the building fabric, and building code ventilation rates should be adhered to.
Parameters that are easy and inexpensive to measure and of immediate operational
health relevance (such as turbidity, disinfectant residual and pH) should be monitored
most frequently and in all pool types.
For a conventional public or semi-public swimming pool with good hydraulics
and filtration, operating within its design bathing load, experience has shown that
adequate routine disinfection should be achieved with a free chlorine level of 1 mg/l
throughout the pool. Lower free chlorine concentrations (0.5 mg/l or less) will be
adequate when chlorine is used in combination with ozone or UV disinfection. Higher
concentrations (up to 2–3 mg/l) may be required for hot tubs, because of higher bathing loads and higher temperatures. Total bromine concentrations should not exceed
4 mg/l in public and semi-public pools and 5 mg/l in hot tubs.
In public and semi-public pools, residual disinfectant concentrations should be
checked by sampling the pool before it opens and during the opening period (ideally
during a period of high bathing load). It is suggested that the residual disinfectant
concentration in domestic pools be determined before use. If the routine test results
are outside the recommended ranges, the situation should be assessed and action
taken.
The pH value of swimming pool water (and similar environments) must be controlled to ensure efficient disinfection and coagulation, to avoid damage to the pool
fabric and to ensure user comfort. The pH should be maintained between 7.2 and
7.8 for chlorine disinfectants and between 7.2 and 8.0 for bromine-based and other
non-chlorine processes.
There is limited risk of significant microbial contamination and illness in a well
managed pool or similar environment with an adequate residual disinfectant concentration, a pH value maintained at an appropriate level, well operated filters and frequent monitoring of non-microbial parameters. Nevertheless, samples of pool water
from public and semi-public pools should be monitored at appropriate intervals for
microbial parameters, including heterotrophic plate count, thermotolerant coliforms
or E. coli, Pseudomonas aeruginosa and Legionella. The frequency of monitoring and
the guideline values vary according to microbial parameter and the type of pool.
Guideline implementation
Recreational water activities can bring health benefits to users, including exercise and
relaxation. Effective management can control potential adverse health consequences
that can be associated with the use of unsafe recreational water environments.
xx
layout Safe Water.indd 20
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:49
Different stakeholders play different roles in the management of the recreational
water environment for safety. The typical areas of responsibility may be grouped into
four major categories, although there may be overlap between these and stakeholders
with responsibilities falling within more than one category:
• Design and construction. People responsible for commissioning pools and similar
environments, along with designers and contractors, should be aware of the requirements to ensure safe and enjoyable use of facilities. Many decisions taken
at the design and construction phase will have repercussions on the ease with
which safe operation can be ensured once the pool is in use.
• Operation and management. Facility operators play a key role and are responsible
for the good operation and management of the recreational water environment.
This should include the preparation of and compliance with a pool safety plan,
which consists of a description of the system, its monitoring and maintenance,
normal operating procedures, procedures for specified incidents, a generic
emergency plan and an emergency evacuation procedure.
• Public education and information. Facility operators, local authorities, public
health bodies, pool-based clubs and sports bodies can play an important role in
ensuring pool safety through public education and providing appropriate and
targeted information to pool users.
• Regulatory requirements (including compliance). National legislation may include
different sets of regulations that will apply to swimming pools and similar recreational environments. Regulation may control, for example, the design and
construction of pools, their operation and management and control of substances hazardous to health. Within regulations it is likely that there will be
a requirement for the use of certified material and, possibly, staff registered to
certain bodies. Local regulatory oversight can support the work of pool management and provide greater public health protection and public confidence.
Inspections by the regulatory officials to verify compliance with the regulations
are an important component of this oversight.
Successful implementation of the Guidelines will also require development of suitable capacities and expertise and the elaboration of a coherent policy and legislative
framework.
EXECUTIVE SUMMARY
layout Safe Water.indd 21
xxi
24.2.2006 9:56:50
layout Safe Water.indd 22
24.2.2006 9:56:50
CHAPTER 1
Introduction
T
his volume of the Guidelines for Safe Recreational Water Environments describes the
present state of knowledge regarding the possible detrimental impacts of the recreational use of swimming pools and similar recreational water environments upon the
health of users, as well as the monitoring and control of the hazards associated with
these environments.
1.1 General considerations
The hazards that are encountered in swimming pools and similar environments vary
from site to site, as does exposure to the hazards. In general, most available information relates to health outcomes arising from exposure through swimming and ingestion of water. In the development of these Guidelines, all available information on the
different uses of water and routes of exposure was taken into consideration.
This chapter covers the structure of this volume of the Guidelines for Safe Recreational Water Environments and introduces definitions of pool types, pool users and
so on. The hazards from drowning and injury are probably the most obvious hazards
relating to pools and similar environments, although there are also less visible hazards,
including those posed by microbes and chemicals. These are covered in Chapters 2, 3
and 4, respectively. Most pools and similar environments apply treatment in managing water quality to ensure that the water is of an acceptable clarity and microbial and
chemical quality. This can encompass filtration, pH control and disinfection with
a range of disinfectants. Managing water and air quality to minimize health risks is
covered in Chapter 5, while the roles of various stakeholders, regulatory measures and
guideline implementation are dealt with in Chapter 6. This volume of the Guidelines
for Safe Recreational Water Environments is structured as shown in Figure 1.1.
The primary aim of the Guidelines for Safe Recreational Water Environments is the
protection of public health. The use of swimming pools and similar recreational water
environments – and the resulting social interaction, relaxation and exercise – is associated with benefits to health and well-being. The purpose of the Guidelines is to ensure
that the pools and similar environments are operated as safely as possible in order that
the largest possible population gets the maximum possible benefit.
The Guidelines are intended to be used as the basis for the development of approaches to controlling the hazards that may be encountered in swimming pools and
similar recreational water environments, as well as providing a framework for policymaking and local decision-taking. The Guidelines may also be used as reference material for industries and operators preparing to develop facilities containing swimming
1
layout Safe Water.indd 23
24.2.2006 9:56:50
1. Introduction
2. Drowning and
injury prevention
3. Microbial hazards
4. Chemical hazards
5. Managing water and air quality
6. Guideline implementation
Design &
construction
Operation &
management
Public education
& information
Regulatory
requirements
Figure 1.1. Structure of Guidelines for Safe Recreational Water Environments, Vol. 2: Swimming
Pools and Similar Environments
pools and similar environments, as well as a checklist for understanding and assessing
the potential health impacts of projects involving the development of such facilities.
The information provided in this volume of the Guidelines is intended to be generally applicable to public, semi-public (as encountered in clubs, hotels and schools,
for example) and domestic (private) facilities (see Section 1.2). Although medical
facilities (such as hydrotherapy pools) and bathing houses, such as hammams, are not
specifically covered, the approaches outlined in these Guidelines should also be generally applicable to these environments. The preferred approaches adopted by national
or local authorities towards implementation of guideline values and conditions may
vary between these types of environment.
Because hazards may give rise to health effects after short- as well as long-term
exposures, it is important that standards, monitoring and implementation enable preventive and remedial actions within real time frames. For this reason, emphasis in the
Guidelines is placed upon identifying circumstances and procedures that are likely
to lead to a continuously safe environment for recreation. This approach emphasizes
monitoring of both conditions and practices and the use of threshold values for key
indicators assessed through programmes of monitoring and assessment.
Concerned bodies – including national and local agencies, facility owners and operators, and nongovernmental organizations – have diverse management interventions.
These range from proper facility planning to good operation and management practices, provision of appropriate levels of supervision (i.e. lifeguards), general educational
activities to enhance awareness of health hazards and inform users on ways to avoid and
respond to the hazards, and compliance with applicable regulatory requirements.
2
layout Safe Water.indd 24
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:50
Where possible, numerical guideline values are presented as indicators of safety or good
management (as described in Section 1.6). These guidelines use a risk–benefit approach. In
the case of swimming pools and similar environments, development of such an approach
concerns not only health risks, but also the health benefits and well-being derived from the
recreational use of these environments. In developing strategies for the protection of public health, competent government authorities should take into account social, economic
and environmental factors, including the general education of adults and children as well
as the efforts and initiatives of nongovernmental organizations and industry operators in
this area. This approach can often lead to the adoption of standards that are measurable
and can be implemented and enforced. These would deal with, for example, water quality,
safety of associated facilities and dissemination of information. A broad-based policy approach is required that will include legislation enabling positive and negative incentives to
alter behaviour and monitor and improve situations. Such a broad base will require significant efforts in intersectoral coordination and cooperation at national and local levels, and
successful implementation will require development of suitable capacities and expertise as
well as the elaboration of a coherent policy and legislative framework.
1.2 Types of pools
Swimming pools may be supplied with fresh (surface or ground), marine or thermal
water (i.e. from natural hot springs). They may be domestic (private), semi-public (e.g.
hotel, school, health club, housing complex, cruise ship) or public (e.g. municipal),
and they may be supervised or unsupervised. Swimming pools may be located indoors,
outdoors (i.e. open air) or both; they may be heated or unheated. In terms of structure,
the conventional pool is often referred to as the main, public or municipal pool. It is
by tradition rectangular, with no extra water features (other than possible provision for
diving), and it is used by people of all ages and abilities. There are also temporary or
portable pools, which are often used in the domestic setting. In addition, there are many
specialist pools for a particular user type – for example, paddling pools, learner or teaching pools, diving pools and pools with special features such as ‘flumes’ or water slides.
Although termed swimming pools, they are often used for a variety of recreational
activities, such as aqua-aerobics, scuba diving and so on (see Section 1.3).
Hot tubs, for the purposes of these Guidelines, is the term used to encompass a
variety of facilities that are designed for sitting in (rather than swimming), contain
water usually above 32 °C, are generally aerated, contain treated water and are not
drained, cleaned or refilled for each user. They may be domestic, semi-public or public
and located indoors or outdoors. A wide range of names is used for them, including spa
pools, whirlpools, whirlpool spas, heated spas, bubble baths and Jacuzzi (a term that is
used generically but is in fact a trade name).
Plunge pools are usually used in association with saunas, steam rooms or hot tubs
and are designed to cool users by immersion in unheated water. They are usually only
large enough for a single person, but can be larger. For the purposes of these Guidelines, they are considered to be the same as swimming pools.
Natural spa is the term used to refer to facilities containing thermal and/or mineral
water, some of which may be perceived to have therapeutic value and because of certain water characteristics may receive minimal water quality treatment.
In addition, there are physical therapy pools, in which treatments for a variety of
physical symptoms are performed by professionals on people with neurological,
CHAPTER 1.
layout Safe Water.indd 25
INTRODUCTION
3
24.2.2006 9:56:50
orthopaedic, cardiac or other diseases; these are termed ‘hydrotherapy pools’ and are
defined as pools used for special medical or medicinal purposes. These are not specifically covered by the Guidelines, although many of the same principles that apply to
swimming pools and hot tubs will also apply to hydrotherapy pools. There are also
therapy pools containing small fish (Garra ruffa) that feed on the scaly skin lesions
caused by psoriasis. These types of therapy pools are not covered by the Guidelines.
In many countries, there are public hygiene facilities to enable individuals and
families to bathe. These are operated as drain and fill pools or baths and are not covered by these Guidelines.
Each type of pool has potentially different management problems, which must be
anticipated and dealt with by pool managers. Of importance to the type of pool and
its management is identification of how the pool will be used:
•
•
•
•
the daily opening hours;
the peak periods of use;
the anticipated number and types of users; and
special requirements, such as temperature, lanes and equipment.
The type, design and use of a pool may present certain hazards (e.g. pools may include sudden changes in depth, which may result in wading non-swimmers suddenly
finding themselves out of their depth). Hot tubs, for example, may be subject to high
bather loads relative to the volume of water. Where there are high water temperatures
and rapid agitation of water, it may become difficult to maintain satisfactory pH,
microbial quality and disinfectant concentrations.
In certain circumstances, in some natural spas utilizing thermal and mineral waters
it may not be possible to treat the water in the usual way (i.e. by recycling or disinfection) because the agents believed to be of benefit, such as sulfides, would be eliminated or impaired. Also, chemical substances of geological origin in some types of deep
thermal springs and artesian wells (such as humic substances and ammonium) may
hamper the effect of disinfectants when these waters are used to fill pools without any
pretreatment. These natural spas, therefore, require non-oxidative methods of water
treatment (see Chapter 5). A very high rate of water exchange is necessary (even if not
completely effective) if there is no other way of preventing microbial contamination,
where complete drain-down between users is not possible.
Pools and hot tubs on ships are also a special case, as the source water may be either
seawater or from the potable water supply for the ship. The hydraulic, circulation and
treatment systems of the pool will necessitate a unique design in order to be able to
deal with movement of the ship and the variable source water quality (outlined in
more detail in WHO, 2005). They may also pose an increased risk of injury compared with land-based pools, especially when used in heavy seas.
1.3 Types of users
Users may include:
•
•
•
•
4
layout Safe Water.indd 26
the general public;
children/babies;
hotel guests;
tourists;
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:51
•
•
•
•
•
•
•
health club members;
exercise class members (e.g. aqua-aerobics);
competitive swimmers;
non-swimmers;
clients of outdoor camping parks;
leisure bathers, including clients of theme parks; and
specialist sporting users, including scuba divers, canoeists and water polo participants.
Certain groups of users may be more predisposed to hazards than others. For example:
• Children may spend long periods in recreational waters and are more likely than
adults to intentionally or accidentally swallow water.
• The elderly and handicapped may have strength, agility and stamina limitations.
• Immunocompromised individuals may be at higher risk from microbial or
chemical hazards.
1.4 Hazard and risk
Popularly, the terms hazard and risk are used interchangeably. Correctly, a hazard is a set
of circumstances that could lead to harm – harm being injury, illness or loss of life. The
risk of such an event is defined as the probability that it will occur as a result of exposure
to a defined quantum of hazard. In simpler terms, hazard is the potential for harm,
while risk is the chance that harm will actually occur. The rate of incidence or attack rate
is the number of events expected to occur for this defined quantum of hazard. Strictly
speaking, probabilities and rates obey different laws; however, if the probabilities are
small and the events are independent, the two values will be approximately equal.
1.4.1 Types of hazard encountered
The most frequent hazards associated with the use of swimming pools and similar
recreational water environments are:
•
•
•
•
physical hazards (leading to, for example, drowning, near-drowning or injury);
heat, cold and sunlight (see also WHO, 2003);
water quality; and
air quality.
Specific examples of the hazards and the associated adverse health outcomes are
given in Table 1.1.
Drowning, near-drowning and spinal injury are severe health outcomes of great
concern to public health. Human behaviour, especially alcohol consumption, is a
prime factor that increases the likelihood of injuries. Other injuries, such as cuts and
those arising from slip, trip and fall accidents, while less severe, cause distress and
decrease the benefits to well-being arising from recreation. Preventive and remedial
actions take diverse forms and include general education, posting of warnings where
appropriate, the presence of lifeguards, use of non-slip surfaces, preventing the use
of glass near the pool, preventing rough play or running poolside, the availability of
health services such as first aid, the availability of communication with health and
rescue services, and the cleaning of pools and associated facilities.
CHAPTER 1.
layout Safe Water.indd 27
INTRODUCTION
5
24.2.2006 9:56:51
Table 1.1. Adverse health outcomes associated with hazards encountered in swimming pools and
similar recreational water environments
Type of adverse
health outcome
Examples of associated hazards
(with chapter references in parentheses)
Drowning
Swimmers under the influence of alcohol, poor swimming ability, no supervision, poor pool design and maintenance (2).
Impact injuries
Impact against hard surfaces (2). The impact may be driven by the participant (diving, accidents arising from the use of water slides, collision,
treading on broken glass and jagged metal – especially in outdoor pool
surroundings).
Physiological
Acute exposure to heat and ultraviolet (UV) radiation in sunlight (refer to
Volume 1 of the Guidelines – WHO, 2003).
Cumulative exposure to sun for outdoor pool users (refer to Volume 1 of
the Guidelines – WHO, 2003).
Heat exposure in hot tubs or natural spas (using thermal water) or cold
exposure in plunge pools (2).
Infection
Ingestion of, inhalation of or contact with pathogenic bacteria, viruses,
fungi and protozoa, which may be present in water and pool surroundings
as a result of faecal contamination, carried by participants or animals
using the water or naturally present (3).
Poisoning, toxicoses
and other conditions
that may arise from
long-term chemical
exposures
Contact with, inhalation of or ingestion of chemically contaminated water,
ingestion of algal toxins and inhalation of chemically contaminated air (4).
Much attention has focused in recent years upon microbial hazards. In particular,
the health risks associated with contamination by excreta and associated gastroenteric
outcomes have been the topic of both scientific and general public interest. Adverse
health outcomes associated with microbial hazards also include skin, eye and ear infections arising from pollution of water by excreta from source waters and from bathers as well as non-enteric organisms arising from bathers or those naturally present in
the aquatic environment.
Hazards to human health exist even in unpolluted environments. For example, eye
irritation and some additional eye infections probably occur as a result of reduction
in the eye’s natural defences through limited contact with water and do not relate to
water quality or pollution per se.
1.4.2 Assessment of hazard and risk
Assessments of hazard and risk inform the development of policies for controlling and
managing risks to health and well-being in water recreation. Both draw upon experience and the application of common sense, as well as the interpretation of data.
Figure 1.2 provides a schematic approach to comparing health hazards encountered
during recreational water use. A severe health outcome such as permanent paralysis or
6
layout Safe Water.indd 28
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:51
Relative risk
(e.g. of outcomes
per bather-year)
Very low
priority
Low
Low priority
Moderate
priority
Very high
priority
Extremely
high priority
Relative severity
High
Life-threatening or
permanent incapacity
(e.g. drowning, spinal
injury, Legionnaires’
disease or primary
amoebic
meningoencephalitis)
Long-term
incapacity (e.g.
near-drowning,
chronic sequelae
as a result of
microbial
infection)
Moderate
incapacity or
requires medical
intervention
(e.g.
leptospirosis)
Short-term
incapacity, selflimiting (e.g.
most mild
diarrhoea, upper
respiratory tract
infection, sunburn, etc.)
Low
No incapacity
(e.g. plantar
warts, minor cuts,
scrapes, etc.)
Figure 1.2. Schematic approach to comparing health hazards encountered during recreational
water use
death, as a result of diving into shallow water, may affect only a small number of pool
users annually but will warrant a high management priority. Minor skin irritations,
encountered at the other end of the scale, may affect a higher number of users per year,
but do not result in any significant incapacity, and thus require lower management priority. Figure 1.2 can be applied throughout the Guidelines. For each hazard discussed,
the severity of the hazard can be related to the relative risk in the figure and can serve
as a tool to initiate further research or investigation into the reduction of risk as well as
to highlight or emphasize priority protective or remedial management measures.
Data on risk related to the use of swimming pools and similar recreational water
environments take four main forms:
•
•
•
•
national and regional statistics of illness and deaths;
clinical surveillance of the incidence of illness and outbreaks;
epidemiological studies and surveys; and
accident and injury records held by facility owners/managers and local authorities.
Although ‘incident records’ held by local pools and authoritative bodies may be comprehensive, published statistics are seldom sufficiently detailed for risk assessment.
Systems for surveillance of public health operate in some countries. They serve
the broad purpose of alerting either regulator or supplier to changes in incidence of
CHAPTER 1.
layout Safe Water.indd 29
INTRODUCTION
7
24.2.2006 9:56:51
disease and to the need for initiating immediate investigation of the causes and remedial action. Such investigation will involve epidemiology (the study of the occurrence
and causes of disease in populations). Galbraith & Palmer (1990) give details of the
use of epidemiology in surveillance. Epidemiology may also be used as a research tool
to investigate hypotheses concerning the causes of illness.
There are other reasons why it is difficult to estimate risk directly, such as the
following:
• In most active water sports, enjoyment arises from the use of skill to avoid and
overcome perceived hazards. The degree of competence of participants and the
use of properly designed equipment, accompanied by appropriate supervision
and training, will considerably modify the risk.
• Risks of acquiring infectious disease will be influenced by innate and acquired
immunity (for examples, see Gerba et al., 1996). The former comprises a wide
range of biological and environmental factors (age, sex, nutrition, socioeconomic and geographic), as well as body defences (impregnability of the skin,
lysozyme secretion in tears, mucus and sweat, the digestive tract and phagocytosis). Previous challenge by pathogens often results in transient or long-lasting
immunity. Immunocompromised individuals will be at greater risk of acquiring
infectious diseases (see Pond, 2005).
• Assessment of harm itself and the degree of harm suffered depends upon judgement at the time. Medical certification of injury and of physiological illness and
infection, accompanied by clinical diagnosis, is the most reliable information.
Information obtained by survey or questionnaire will contain a variable degree
of uncertainty caused by the subjects’ understanding of the questions, their
memory of the events and any personal bias of the subject and interviewer.
Survey information is only as good as the care that has gone into the design and
conduct of the survey.
• The causes of harm must be ascertained as far as possible at the time. There are
considerable difficulties in determining causes in the cases of low-level exposures
to chemical and physical agents that have a cumulative or threshold effect and of
infectious diseases caused by those pathogens that have more than one route of
infection or have a long period of incubation. For example, gastroenteric infections
at swimming pool facilities may result from person-to-person contact or faulty
food hygiene in catering, as well as from ingesting pathogen-contaminated water.
• Where data are in the form of published regional or national statistics giving attack rates, the exact basis on which the data are collected and classified must be
ascertained. For example, national statistics on deaths by drowning will usually
include suicides, occupational accidents (e.g. lifeguards), natural disasters (e.g.
flooding due to storm events) and misadventure in recreation.
• It cannot be assumed that risk is directly proportional to exposure or that risks from
multiple exposures or a combination of different factors will combine additively.
1.4.3 Degree of water contact
For hazards where contact with water and ingestion of water are important, an understanding of the different degrees of contact associated with different pool types
and uses is helpful. For example, the degree of water contact directly influences the
8
layout Safe Water.indd 30
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:52
amount of exposure to pathogens and toxic agents found in contaminated water and
aerosols and therefore the likelihood of illness.
The degrees of water contact encountered in the many different types of swimming pools and similar recreational water environments may be classified as follows:
• No contact – for example, use of outdoor pools just for sunbathing and not
swimming.
• Meaningful direct contact – involves a negligible risk of swallowing water, such
as the use of a wading pool by adults.
• Extensive direct contact – with full body immersion and a significant risk of swallowing water, e.g. swimming, diving.
1.5 Measures to reduce risks
Reduction of most, if not all, of the health risks associated with the hazards described in
Table 1.1 can be obtained by avoiding the circumstances giving rise to the hazard or by
mitigating their effect. For example, glass left on the poolside may cause cuts to walkers
with bare feet, which may be overcome by regular cleaning of the pool, excluding glass
from the pool area, provision of litter bins and educational awareness campaigns. Accidents caused by misuse of water slides may be overcome by increased supervision by
lifeguards and education of users regarding proper behaviour. Each type of recreational
activity should be subject to a hazard assessment to determine what type of control measures will be most effective. Assessment should include modifying factors, such as local
features, seasonal effects (for outdoor pools) and competence of the participants.
Controls for reducing risks in swimming pools and similar environments are discussed in Chapters 5 and 6. Different uses and types of pools involve different degrees
of water contact and exposure to the various hazards. Measures for risk reduction will
therefore be tailor-made to each pool type and to particular circumstances.
Management of swimming pools and similar recreational waters can be classified
into four major categories (as described in Chapter 6):
• design and construction of facilities (including licensing and authorization, as
appropriate);
• operation and management (including pool safety plan and lifeguard training);
• public education and information; and
• regulatory requirements (including licensing of equipment, chemicals, etc.,
available for use in swimming pools and similar environments).
1.6 Nature of the guidelines
A guideline can be a level of management, a concentration of a constituent that does
not represent a significant risk to the health of members of significant user groups,
a condition under which exposures associated with a significant risk are unlikely to
occur, or a combination of the last two. In deriving guidelines including guideline
values, account is taken of both the severity and frequency of associated health outcomes. Recreational water use areas conforming to the guidelines may, however, present a health risk to especially susceptible individuals or to certain user groups.
When a guideline is exceeded, this should be a signal to investigate the cause of
the failure and identify the likelihood of future failure, to liaise with the authority
responsible for public health to determine whether immediate action should be taken
CHAPTER 1.
layout Safe Water.indd 31
INTRODUCTION
9
24.2.2006 9:56:52
to reduce exposure to the hazard, and to determine whether measures should be put
in place to prevent or reduce exposure under similar conditions in the future.
For most parameters, there is no clear cut-off value at which health effects are
excluded, and the derivation of guidelines and their conversion to standards therefore
include an element of valuation addressing the frequency and nature of associated
health effects. This valuation process is one in which societal values play an important role. The conversion of guidelines into national policy, legislation and standards should therefore take account of environmental, social, cultural and economic
factors.
Many of the hazards associated with swimming pools and similar recreational water
environments may give rise to health effects after short-term exposures: accidents and
exposures to microbial infective doses may occur in very short periods of time. Shortterm deviations above guideline values or conditions are therefore of importance to
health, and measures should be in place to ensure and demonstrate that recreational
water environments are continuously safe during periods of actual or potential use.
This volume of the Guidelines for Safe Recreational Water Environments does not
address:
• occupational exposures of individuals working in recreational water environments;
• waters afforded special significance for religious purposes and which are therefore subject to special cultural factors;
• therapeutic uses of water (hydrotherapy, balneotherapy or thalassotherapy);
• facilities, such as bathing houses, that are drained and refilled between users;
• risks associated with ancillary facilities that are not part of swimming pools and
similar recreational water environments — thus, while poolside surfaces are addressed, toilet facilities in adjacent areas are not considered beyond assertion of
the need for them in order to minimize soiling of the recreational environment;
• ‘biopools’, which are artificially created small ‘lakes’ (which can be either indoors or outdoors) that are sealed against groundwater and natural surface water influence and are becoming increasingly popular. In these pools the water
is not disinfected but is circulated through ‘regeneration’ areas (reeds or soil
filters);
• electrocution;
• hazards associated with UV radiation (from sunlight);
• aesthetic factors;
• beneficial effects, health claims, the efficacy of therapeutic use or the scale of
health benefits arising from relaxation and exercise associated with recreational
water use; or
• rescue, resuscitation or evacuation procedures from swimming pools and other
recreational water facilities.
1.7 References
Galbraith S, Palmer S (1990) General epidemiology. In: Smith GR, Easmon CSF, eds. Topley and Wilson’s principles of bacteriology, virology and immunity. Vol. 3. Bacterial diseases. London, Edward Arnold, pp. 11–29.
Gerba CP, Rose JB, Haas CN (1996) Sensitive populations: who is at the greatest risk? International Journal
of Food Microbiology, 30(1–2): 113–123.
10
layout Safe Water.indd 32
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:52
Pond K (2005) Water recreation and disease: An expert review of the plausibility of associated infections, their
acute effects, sequelae and mortality. IWA on behalf of the World Health Organization, London, UK.
WHO (2003) Guidelines for safe recreational water environments. Vol. 1. Coastal and fresh waters. Geneva,
World Health Organization, 219 pp.
WHO (2005) Guide to ship sanitation. Geneva, World Health Organization, in preparation.
CHAPTER 1.
layout Safe Water.indd 33
INTRODUCTION
11
24.2.2006 9:56:53
CHAPTER 2
Drowning and injury prevention
A
number of injuries may result from the use of swimming pools and similar recreational water environments. Prominent among them are:
•
•
•
•
drowning and non-fatal or near-drowning;
major impact injuries (spinal, brain and head injuries);
slip, trip and fall injuries; and
disembowelment.
This chapter addresses these adverse health outcomes, their causation and contributory factors, along with evidence concerning preventive measures.
2.1 Drowning
Drowning has been defined as death arising from impairment of respiratory function
as a result of immersion in liquid, and this is the definition employed in these Guidelines. A wider definition of drowning includes outcomes ranging from no morbidity
to morbidity to death (World Congress on Drowning, 2002). Drowning is a major
cause of death, and it has been estimated that, in 2002, 382 million people drowned
worldwide, with 97% of drownings occurring in low- and middle-income countries
(Peden & McGee, 2003; WHO, 2004), although the majority of available data relate
to developed countries. It is the third leading cause of death in children aged 1–5 and
the leading cause of mortality due to injury, with the mortality rates in male children
being almost twice as high as those in female children (Peden & McGee, 2003). Not
all drownings are related to recreational water use, and the percentage that is attributable to swimming pools and similar environments is likely to vary from country to
country.
Overall drowning statistics (i.e. not confined to swimming pools) for the USA,
shown in Table 2.1, support the observation from numerous studies that children
less than 5 years of age and young adults between the ages of 15 and 24 years have
the highest drowning rates (e.g. Blum & Shield, 2000; Browne et al., 2003; Smith,
2005).
In the USA, an investigation into drownings in New York State residents (with a
population of almost 18 million) between 1988 and 1994 found that there were on
average 173 drownings a year (1210 over the seven-year period). A total of 883 nonbathtub drownings that took place in-state were included in the study. Of these, 156
(18%) took place in pools or hot tubs (Browne et al., 2003), with domestic pools
predominating (123 cases). Almost 60% of drownings in children aged 0–4 years,
however, occurred in swimming pools or hot tubs. Analysis of figures from the whole
12
layout Safe Water.indd 34
24.2.2006 9:56:53
Table 2.1. Drowning statistics for the USA (per 100 000)a
1997
1996
1995
Ages
(years)
Deaths
Rates
Deaths
Rates
Deaths
Rates
0–4
5–9
10–14
15–19
20–24
25–29
516
234
215
349
316
298
2.69
1.19
1.13
1.83
1.80
1.58
533
223
225
388
327
291
2.76
1.15
1.19
2.08
1.86
1.53
596
222
242
442
348
292
3.05
1.16
1.29
2.43
1.93
1.54
a
Adapted from National Center for Health Statistics, 1998
of the USA for 2001 reveals similar results, with 18% of fatal drownings occurring
in swimming pools (CDC, 2004). In the State of Arizona, USA, 85% of emergency
calls relating to drownings and near-drownings in children aged four or less were
associated with swimming pools (CDC, 1990). In the United Kingdom, children
are more likely to drown in natural water bodies (sea, lakes, etc.) than in swimming
pools, although pools still account for a substantial proportion of drowning, with
19% of drowning deaths in children aged 0–14 years being attributable to pools
in 1988–1989, and 11% in 1998–1999 (Sibert et al., 2002). These authors note,
however, that at least 14 British children drowned while abroad, with most of these
drownings occurring in hotel or apartment pools.
During a period of over 20 years (since 1980), the USA Consumer Product Safety Commission (CPSC) has received reports of more than 700 deaths in hot tubs.
Approximately one third of these were drownings of children under five years of age
(CPSC, undated).
Death by drowning is not the sole outcome of distress in the water. Near-drowning is
also a serious problem. One study (Wintemute et al., 1987) found that for every 10 children who die by drowning, 140 are treated in emergency rooms and 36 are admitted to
hospitals for further treatment (see also Spyker, 1985; Liller et al., 1993), although some
never recover. In the Netherlands, it has been reported that on average there are about 300
drowning fatalities a year and an additional 450 cases who survive the drowning incident;
of these, 390 are admitted to hospital for further treatment (Bierens, 1996). Browne et
al. (2003) reported that there are on average 173 drownings among New York State residents every year, and it is estimated that there are 177 non-fatal hospitalizations. Analysis
of data from the USA for 2001–2002 led to the estimation that about 4174 people on
average each year are treated in hospital emergency departments for non-fatal drowning
injuries in recreational water settings, over 65% of these cases occurred in swimming
pools and over 52% were in children under the age of 5 (CDC, 2004).
The recovery rate from near-drowning may be lower among young children than
among teenagers and adults. Some survivors suffer subsequent anoxic encephalopathy
(Pearn et al., 1976; Pearn & Nixon, 1977) leading to long-term neurological deficits
(Quan et al., 1989). Studies show that the prognosis depends more on the effectiveness of the initial rescue and resuscitation than on the quality of subsequent hospital
care (Cummings & Quan, 1999).
CHAPTER 2.
layout Safe Water.indd 35
DROWNING AND INJURY PREVENTION
13
24.2.2006 9:56:53
2.1.1 Contributory factors
Males are more likely to drown than females (Browne et al., 2003; Peden & McGee,
2003). This is generally attributed to higher exposure to the aquatic environment and
a higher consumption of alcohol (leading to decreased ability to cope and impaired
judgement) and their inclination towards higher risk-taking activity (Dietz & Baker,
1974; Mackie, 1978; Plueckhahn, 1979; Nichter & Everett, 1989; Quan et al., 1989;
Howland et al., 1996).
Alcohol consumption is one of the most frequently reported contributory factors associated with adolescent and adult drownings in many countries (Howland &
Hingson, 1988; Levin et al., 1993; Browne et al., 2003; Petridou, 2005). Although
the proportion of alcohol-related drownings is often not presented according to body
of water (and swimming pools and hot tubs are the site of relatively few adult and
adolescent drownings), in one study a blood alcohol screen was positive for approximately 50% of drowning victims over 14 years of age (M. Browne, pers. comm.).
Among children, lapses in parental supervision are the most frequently cited contributory factor (Quan et al., 1989), although alcohol consumption by the parent or
guardian may also play a role in the lapse of supervision (Petridou, 2005).
Browne et al. (2003) examined the means of access of young children involved in domestic swimming pool drownings. The following were found to be the most common:
• open or unlocked gate or ineffective latch;
• no fence, no separate fence (completely enclosing the pool area) or fence in
disrepair;
• access directly from the house; and
• ladder to above-ground pool left in accessible ‘down’ position.
In this study, 43 of 77 (56%) of the drownings in children aged 0–4 occurred in the
child’s family pool, 17 (22%) occurred in the domestic pool of a relative and 8 (10%)
occurred in a neighbour’s domestic pool (M. Browne, pers. comm.).
In Australia, a similar study found that more than half of the children studied
drowned in unfenced or unsecured pools and hot tubs. Where children gained access
to fenced pools, most did so through faulty or inadequate gates or through gates that
were propped open (Blum & Shield, 2000). Access has also infrequently been as a
result of climbing onto objects next to the pool fence (e.g. pool filters).
While a high proportion of persons drowning are non-swimmers or poor swimmers (Spyker, 1985), there are conflicting opinions as to the role of swimming skills
in preventing drowning and near-drowning (Patetta & Biddinger, 1988; Asher et al.,
1995; Brenner, 2005). Hyperventilation before breath-hold swimming and diving has
been associated with a number of drownings among individuals, almost exclusively
males, with excellent swimming skills. Although hyperventilation makes it possible
for a person to extend his or her time under water, it may result in a loss of consciousness by lowering the carbon dioxide level in the blood and decreasing the partial oxygen pressure in the arterial blood on surfacing (Craig, 1976; Spyker, 1985).
Inlets and outlets where the suction is extremely strong can trap body parts or hair,
causing the victim’s head to be held under water. Most accidents involve people with
shoulder-length or longer hair. Hair entrapment occurs when the water flow into the
inlet takes the bather’s hair into and around the outlet cover, and the hair is pulled
into the drain as a result of the suction created. In the USA, during a six and a half
14
layout Safe Water.indd 36
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:53
year period, between 1990 and 1996, the CPSC received reports of 49 incidents of
hair entrapment/entanglement in hot tubs, 13 of which resulted in drowning (CPSC,
undated). This suction problem may also occur in the main pool drains of swimming
pools, but to a much lesser extent than with hot tubs.
A number of drowning deaths have also occurred after the body or a limb has
been held against a drain by the suction of the circulation pump. In the USA, CPSC
reported 18 cases of body entrapment over a 20-year period. Ten of these resulted in
disembowelment (see Section 2.5), and five other cases were fatal (CPSC, undated).
Young children, typically between the ages of 8 and 16 years, are particularly likely
to play with open drains, inserting hands or feet into the pipe and then becoming
trapped with the resulting suction. Any open drain or flat grating that the body can
cover completely, combined with a plumbing layout that allows a build-up of suction
if the drain is blocked, presents this hazard.
High temperatures (above 40 °C) in spas or hot tubs, especially in combination
with alcohol consumption, may cause drowsiness, which may lead to unconsciousness
and, consequently, drowning (Press, 1991).
Further contributory factors in drowning and near-drowning include:
• those related to the bather, such as a pre-existing health condition (e.g. seizure
disorder – Ryan & Dowling, 1993);
• those related to the staff, such as lack of proper training for emergency response; and
• those related to the pool facility, such as water depth, water clarity, pool configuration and pool size.
Water clarity is particularly critical to water safety. If it is not possible to see the
bottom of the pool at its deepest point, pool users and lifeguards may not be able to
identify people in distress. In addition, a person entering the pool may not be able to
see someone under the water or may not be able to judge the pool bottom configuration. Natural and artificial reflected light from the water surface may also affect vision
in a similar way to poor water clarity. Swimming pool designers need to consider this
when locating windows and designing lighting systems.
2.1.2 Preventive and management actions
It has been estimated that over 80% of all drownings can be prevented, and prevention
is the key management intervention (World Congress on Drowning, 2002; Mackie,
2005). Surprisingly, there is no clear evidence that drowning rates are greater in poor
swimmers (Brenner, 2005), and the value of swimming lessons and water safety instruction as drowning preventive measures has not been demonstrated (Patetta & Biddinger, 1988; Mackie, 2005). There is a significant debate regarding the age at which
swimming skills may be safely acquired. The need for adult supervision is not decreased
when young children acquire increased skills, and the possibility that training decreases
parental vigilance has not been assessed (Asher et al., 1995). Lapses in supervision may
make this an insufficient preventive measure alone (Quan et al., 1989).
Children should be taught to stay away from water and pools when unsupervised,
but for outdoor pools, care must also be taken to prevent unauthorized entry (especially by young children). For domestic pools, barriers such as fences or walls will prevent
some drownings by preventing a child from entering a swimming pool area unsupervised or may delay their entry long enough for the carer to realize they are missing.
CHAPTER 2.
layout Safe Water.indd 37
DROWNING AND INJURY PREVENTION
15
24.2.2006 9:56:54
Installation of isolation fencing around outdoor pools, which separates the pool from
the remaining yard and house, has been shown in some studies to decrease the number
of drownings and near-drownings by more than 50% (Pearn & Nixon, 1977; Milliner
et al., 1980; Present, 1987). In Australia, Blum & Shield (2000) found that in the
childhood drowning that they studied, no child had gained unaided access to a pool
fitted with a fully functional gate and fence that met the Australian standard. A systematic review of studies (Thompson & Rivara, 2000) examining the effectiveness of pool
fencing indicated that pool fencing significantly reduced the risk of drowning, with
isolation fencing (enclosing the pool only) being superior to perimeter fencing (enclosing the pool and the property). The results of the review are supported by Stevenson et
al. (2003). This study, conducted in Australia, found that during a 12-year period 50
children under the age of five drowned in domestic swimming pools and 68% of the
drownings occurred in pools that did not have isolation fencing. Pool fences around
domestic pools should have a self-closing and self-latching gate and should isolate the
pool. Barrier fencing should be at least 1.2 m high and have no hand- or footholds
that could enable a young child to climb it. Fence slats should be no more than 10 cm
apart to prevent a child squeezing through, thus ensuring that the safety barrier itself is
not a hazard. Above-ground pools should have steps or ladders leading to the pool that
can be secured and locked to prevent access when the pool is not in use. Care should
also be taken to ensure that poolside equipment is not positioned such that it may be
used to climb the fence and access the pool. For domestic or outdoor hot tubs, it is
recommended that locked safety covers be used when the hot tub is not in use.
Pool alarms and pool covers have not been shown to be reliable preventive measures
for very young children. In fact, pool covers may themselves contribute to drowning – if
they are not strong enough to hold the child’s weight, the child could slip under the cover
and be trapped by it, or the child could drown in small puddles of water formed on their
surface. In addition, covers may delay the discovery of a drowning victim.
To prevent entrapment, it is recommended that the velocity of water flowing from
the pool through outlets should not exceed 0.5 m/s and there should be a minimum
of two outlets to each suction line. Also, they should be sized and located such that
they cannot be blocked by the body of a single bather. Grilles in outlets should have
gaps of less than 8 mm. In addition, pools and hot tubs should not be used if any of
the covers are missing, unsecured or damaged.
The availability of cardiopulmonary resuscitation (CPR) (including infant and
child CPR) skills (Patetta & Biddinger, 1988; Orlowski, 1989; Liller et al., 1993;
Kyriacou et al., 1994; Pepe & Bierens, 2005) has been reported to be important in
determining the outcome of potential drownings.
The principal contributory factors and preventive actions (some of which have
received scientific evaluation) concerned with drowning and near-drowning are summarized in Table 2.2.
2.2 Spinal injury
Data concerning the number of spinal injuries sustained as a result of pool use are not
widely available. Stover & Fine (1987) estimated the total prevalence of spinal cord
injury in the USA to be around 906 per million, with an annual rate of incidence of
around 30 new spinal cord injuries per million persons at risk, and according to the
Think First Foundation (2004), USA, 10% of all spinal cord injuries are related to
16
layout Safe Water.indd 38
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:54
Table 2.2. Drowning and near-drowning: Principal contributory factors and preventive and
management actions
Contributory factors
• Falling unexpectedly into water
• Easy unauthorized access to pools
• Not being able to swim
• Alcohol consumption
• Excessive ‘horseplay’ or overexuberant behaviour
• Swimming outside the depth of the user
• Breath-hold swimming and diving
• High drain outlet suction and poor drain and drain cover design
• High water temperatures
Preventive and management actions
• Isolation fences with self-closing and self-latching gates around outdoor pools
• Locked steps/ladders for above-ground pools
• Locked doors for indoor pools
• Locked safety covers for domestic and outdoor hot tubs
• Continuous parental/caregiver supervision of children
• Provision of properly trained and equipped lifeguards
• Teaching children to stay away from water when unsupervised
• Education/public awareness that drowning can happen quickly and quietly
• Restriction of alcohol provision or supervision where alcohol is likely to be consumed
• Suction outlets cannot be sealed by single person, and at least two suction outlets per pump
• Accessible emergency shut-off for pump
• Grilles/pipes on drain gates preclude hair entrapment
• Wearing bathing caps
• Maintaining water temperature in hot tubs below 40 °C
• Access to emergency services
diving into water. In Ontario, Canada, Tator & Edmonds (1986) report that between
1948 and 1983, diving accounted for 58.9% of all recreational-related spinal cord
injury – 60 major spinal injuries each year.
Blanksby et al. (1997) tabulated data from a series of studies concerning diving
accidents as the cause of acute spinal injury in various regions of the world. In one
study (Steinbruck & Paeslack, 1980), 212 of 2587 spinal cord injuries were sports
related, 139 of which were associated with water sports, the majority (62%) with diving. Diving-related injuries were found to be responsible for between 3.8% and 14%
of traumatic spinal cord injuries in a comparison of French, Australian, English and
American studies (Minaire et al., 1983), for 2.3% in a South African study and for
21% in a Polish study (Blanksby et al., 1997).
In diving incidents of all types, spinal injuries are almost exclusively located in the
cervical vertebrae (Minaire et al., 1983; Blanksby et al., 1997). Statistics such as those
cited above therefore underestimate the importance of these injuries, which typically
cause quadriplegia (paralysis affecting all four limbs) or, less commonly, paraplegia
(paralysis of both legs). In Australia, for example, diving incidents account for approximately 20% of all cases of quadriplegia (Hill, 1984). The financial cost of these
injuries to society is high, because persons affected are frequently healthy young people, typically males under 25 years of age (DeVivo & Sekar, 1997).
CHAPTER 2.
layout Safe Water.indd 39
DROWNING AND INJURY PREVENTION
17
24.2.2006 9:56:54
2.2.1 Contributory factors
Data from the USA suggest that diving into the upslope of a pool bottom or shallow
water is the most common cause of spinal injuries in pools. Diving or jumping from
trees, balconies and other structures is particularly dangerous, as are special dives such
as the swan or swallow dive, because the arms are not outstretched above the head but
are to the side of the body (Steinbruck & Paeslack, 1980). Familiarity with the pool may
not necessarily be protective; in one study from South Africa (Mennen, 1981), it was
noted that the typical injurious dive is into a water body known to the individual.
Minimum depths for safe diving are greater than is frequently perceived, but the
role played by water depth has been debated. Inexperienced or unskilled divers require greater depths for safe diving. The velocities reached from ordinary dives are
such that the sight of the bottom, even in clear water, may provide an inadequate time
for deceleration response (Yanai et al., 1996).
Most diving injuries occur in relatively shallow water (1.5 m or less) and few in
very shallow water (i.e. less than 0.6 m), where the hazard may be more obvious (Gabrielsen, 1988; Branche et al., 1991). In a sample of 341 persons with spinal injuries
resulting from swimming pool incidents, over half of the injuries occurred when the
individuals dived into less than 1.2 m of water (DeVivo & Sekar, 1997).
Alcohol consumption may contribute significantly to the frequency of injury, through
diminished mental faculties and poor judgement (Howland et al., 1996; Blanksby et
al., 1997). Young males appear to be more likely to experience spinal injury; in the
study by DeVivo & Sekar (1997), 86% of the 341 persons with spinal injuries resulting from swimming pool incidents were men, with an average age of 24 years. A lack
of signage may also be a contributory factor. In the same study, almost all the injuries
(87%) occurred in private/domestic pools; depth indicators were not present in 75% of
cases, and there were no warning signs in 87% of cases (DeVivo & Sekar, 1997).
A proportion of spinal injuries will lead to death by drowning. While data on this
are scarce, it does not appear to be common (see, for example, EEA/WHO, 1999).
The act of rescue from drowning may also exacerbate spinal cord trauma after the
initial impact (Mennen, 1981; Blanksby et al., 1997) because of the movements of
the spine during the rescue technique.
2.2.2 Preventive and management actions
The principal contributory factors and preventive actions for spinal cord injuries are
summarized in Table 2.3. Evidence suggests that diving technique and education are important in injury prevention (Perrine et al., 1994; Blanksby et al., 1997), and preventive
programmes can be effective. In Ontario, for example, the establishment of preventive
programmes by Sportsmart Canada and widespread education decreased the incidence
of water-related injuries substantially between 1989 and 1992 (Tator et al., 1993).
Because of the young age of many injured persons, awareness raising and education regarding safe behaviours are required early in life. Many countries have schoolage swimming instruction that may inadequately stress safe diving, but which may
provide a forum for increased public safety (Damjan & Turk, 1995). Education and
awareness raising appear to offer the most potential for diving injury prevention, in
part because some people have been found to take little notice of posted signs and
regulations (Hill, 1984) in isolation.
18
layout Safe Water.indd 40
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:54
Table 2.3. Spinal injury: Principal contributory factors and preventive and management actions
Contributory factors
• Diving into a shallow pool or the shallow end of a pool
• Diving into a pool of unknown depth
• Improper diving
• Jumping or diving into water from trees/balconies/other structures
• Poor underwater visibility
• Alcohol consumption
• Lack of supervision
• Lack of signage
Preventive and management actions
• Lifeguard supervision
• General public (user) awareness of depth hazards and safe behaviours
• Early education in diving hazards and safe behaviours/diving instruction
• Restriction of alcohol provision or supervision where alcohol is likely to be consumed
• Poolside wall markings
• Access to emergency services
2.3 Brain and head injuries
Impact on the skull and injuries to the head, including scalp and facial abrasions and
breaks, have been associated with swimming pools and similar environments and may
result in permanent neurological disability, as well as disfigurement. The contributory
factors and preventive and management actions are similar to those for spinal injuries and
for limb and minor impact injuries and are summarized in Table 2.3 and Table 2.4.
2.4 Fractures, dislocations, other impact injuries, cuts and lesions
Arm, hand, leg and foot/toe injuries have occurred from a variety of activities in pools
and their immediate surroundings. Expert opinion suggests that these incidents are
common and generally go unreported. Slippery decks, uneven pavements, uncovered
drains and exposed pool spouts may cause injuries to pool users. Reckless water entries, such as jumping onto others in the pool from poolside or from dive boards on
the pool deck, jumping into shallow water, running on decks and water slide-related
incidents (see Section 2.7), may also result in injury. Slip, trip and fall accidents may
be the result of swimming aids, such as rings, floats, etc., left around the pool area.
There are reports of injuries sustained as a result of stepping on glass, broken bottles
and cans. Banning of glass containers and use of alternative materials for drinks in the
pool and hot tub area will minimize these types of injuries.
Maintenance of surfaces, supervision of pool users, providing appropriate warnings, improved pool design and construction, ensuring good underwater visibility and
pool safety education are among the actions that can reduce these incidents. Table 2.4
provides examples of some of the factors that contribute to impact injuries and associated preventive and management actions.
CHAPTER 2.
layout Safe Water.indd 41
DROWNING AND INJURY PREVENTION
19
24.2.2006 9:56:55
Table 2.4. Limb, minor impact injuries, cuts and lesions: Principal contributory factors and
preventive and management actions
Contributory factors
• Diving or jumping into shallow water
• Overcrowded pool
• Underwater objects (e.g. ladders)
• Poor underwater visibility
• Slippery decks
• Glass or rubbish around the pool area
• Swimming aids left poolside
Preventive and management actions
• Lifeguard supervision
• General user awareness of hazards and safe behaviours
• Appropriate surface type selection
• Appropriate cleaning and litter control
• Use of alternative materials to glass
• Limits on bather numbers
2.5 Disembowelment
In addition to hair and body entrapment resulting in drowning (Section 2.1.1), there
have been reports of incidents in which the suction from the pool or spa drain has
pulled intestines out of the body (Hultman & Morgan, 1994; Porter et al., 1997;
Gomez-Juarez et al., 2001). In the USA, for example, 18 incidents of evisceration/disembowelment were reported to the CPSC during a 20-year period (CPSC, undated).
In the UK, a six-year-old girl suffered a rectal prolapse after being sucked onto a
swimming pool drain from which the cover had been removed (Davison & Puntis,
2003). The drain, which was located on the second of the steps giving access to the
water, had not been recovered after cleaning.
The drain covers in pools and hot tubs can become brittle and crack, or they may
become loose or go missing. If a person sits on a broken cover or uncovered drain,
the resulting suction force can cause disembowelment. This is a particular hazard for
young children in shallow pools.
Preventive measures are similar to those against entrapment leading to drowning
(see Table 2.2). It is uncertain if reduced vacuum (e.g. through multiple outlets and a
maximum velocity – see Section 2.1.2) is as effective against disembowelment injuries
as it is against drowning, since these occur almost immediately at a small pressure differential. It is recommended that drain covers be designed to avoid the possibility of
disembowelment by, for example, having no openings on the top, with the water entering the drain through a series of openings on the side.
2.6 Hazards associated with temperature extremes
Water ranging in temperature from 26 to 30 °C is comfortable for most swimmers
throughout prolonged periods of moderate physical exertion. The comfortable upper
limit of water temperature for recreational immersion varies from individual to individual and seems to depend on psychological rather than physiological considerations.
20
layout Safe Water.indd 42
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:55
Body overheating can occur in natural spas and hot tubs, where water temperatures may be above 40 °C. High temperatures can cause drowsiness, which may lead
to unconsciousness (especially when associated with alcohol consumption), resulting
in drowning (Press, 1991; see Section 2.1). In addition, high temperatures can lead
to heat stroke and death (CPSC, undated). The CPSC has received reports of several
deaths from extremely hot water (approximately 43 °C) in hot tubs (CPSC, undated).
It is recommended that water temperatures in hot tubs be kept below 40 °C.
Plunge pools present similar problems, but at the other temperature extreme.
These small, deep pools generally contain water at a temperature of 8–10 °C and are
used in conjunction with saunas or steam baths. Adverse health outcomes that may
result from the intense and sudden changes in temperature associated with the use
of these pools include immediate impaired coordination, loss of control of breathing
and, after some time when the core body temperature has fallen, slowed heart beat,
hypothermia, muscle cramps and loss of consciousness.
In general, exposure to temperature extremes should be avoided by pregnant
women, users with medical problems and young children, and prolonged immersion
in hot tubs or other pools with high or low temperatures should be avoided or approached with caution.
Educational displays and warning signs, warnings from lifeguards and pool staff,
regulations on time limits for exposure and limiting use by people with medical conditions are some examples of preventive actions for hazards associated with temperature extremes (see Table 2.5). Further information on this subject is given in Volume
1 of the Guidelines for Safe Recreational Water Environments (WHO, 2003).
Table 2.5. Hazards associated with temperature extremes: Principal contributory factors and
preventive and management actions
Contributory factors
• Cold plunge when not conditioned
• Prolonged immersion in hot water
Preventive and management actions
• Supervision
• Signage, including time limits for exposure
• A maximum temperature of 40 °C for hot tubs
• Gradual immersion
• Medical recommendations for pregnant women, people with medical conditions
• Limitation of alcohol intake prior to use of hot tubs
2.7 Injuries associated with ‘feature pools’
Pools may contain features that present their own particular requirements to ensure
safe use. Water slides add excitement but may present physical hazards, particularly
where riders go down in pairs, too close to each other or headfirst; or where riders
stop, slow down or stand up on the slide. Failure to leave the area immediately after
arriving from the slide may also present physical hazards. In the USA, CDC reported
CHAPTER 2.
layout Safe Water.indd 43
DROWNING AND INJURY PREVENTION
21
24.2.2006 9:56:55
injuries relating to the use of a water slide (CDC, 1984). The slide consisted of two
fibreglass tubes, 1.2 m wide and over 100 m in length. In a six-week period, 65
people were injured while using the slide and sought medical care. Injuries included
fractures, concussions, bruises and abrasions and sprains and strains. This included
nine spinal fractures.
Wave machines may provide a higher level of excitement and also often increased
bather load. Extra vigilance is needed by lifeguards and bathers alike. The possibility
exists for entrapment of limbs in wave machine chambers; therefore, all parts of the
wave machine should be enclosed by a guard. As grilles must be large enough to allow
water flow, adequate supervision to prevent users holding onto the grilles, when the
waves are in action, may also be necessary.
In-water features may also present a physical hazard, as they may be slippery or
encourage climbing, falls from which could injure the climber or other user. Design
issues, user awareness and education are important considerations in feature pools.
2.8 References
Asher KN, Rivara FP, Felix D, Vance L, Dunne R (1995) Water safety training as a potential means of
reducing risk of young children’s drowning. Injury Prevention, 1(4): 228–233.
Bierens JJLM (1996) 2944 submersion victims: an analysis of external causes, concomitant risk factors,
complications and prognosis. In: Drownings in the Netherlands. Pathophysiology, epidemiology and clinical
studies, PhD thesis Netherlands, University of Utrecht.
Blanksby BA, Wearne FK, Elliott BC, Biltvich JD (1997) Aetiology and occurrence of diving injuries. A
review of diving safety. Sports Medicine, 23(4): 228–246.
Blum C, Shield J (2000) Toddler drowning in domestic swimming pools. Injury Prevention, 6: 288–290.
Branche CM, Sniezek JE, Sattin RW, Mirkin IR (1991) Water recreation-related spinal injuries: Risk factors in natural bodies of water. Accident Analysis and Prevention, 23(1): 13–17.
Brenner R (2005) Swimming lessons, swimming ability and the risk of drowning. In: Bierens JJLM et al.,
eds. Handbook on drowning. Prevention, rescue and treatment. Netherlands, Springer, in press.
Browne Ml, Lewis-Michl EL, Stark AD (2003) Unintentional drownings among New York State residents,
1988–1994. Public Health Reports, 118(5): 448–458.
CDC (1984) Injuries at a water slide – Washington. Morbidity and Mortality Weekly Report, 33(27): 379–
382, 387.
CDC (1990) Current trends child drownings and near drownings associated with swimming pools – Maricopa County, Arizona, 1988 and 1989. Morbidity and Mortality Weekly Report, 39(26): 441–442.
CDC (2004) Nonfatal and fatal drownings in recreational water settings – United States, 2001–2002.
Morbidity and Mortality Weekly Report, 53(21): 447–452.
CPSC (undated) Spas, hot tubs, and whirlpools. Washington, DC, United States Consumer Product Safety
Commission (CPSC Document #5112; http://www.cpsc.gov/cpscpub/pubs/5112.html, accessed 15 November 2004).
Craig AB Jr (1976) Summary of 58 cases of loss of consciousness during underwater swimming and diving.
Medicine and Science in Sports, 8(3): 171–175.
Cummings P, Quan L (1999) Trends in unintentional drowning. The role of alcohol and medical care.
Journal of the American Medical Association, 281: 2198–2202.
Damjan H, Turk KK (1995) Prevention of spinal injuries from diving in Slovenia. Paraplegia, 33(5): 246–249.
Davison A, Puntis JWL (2003) Awareness of swimming pool suction injury among tour operators. Archives
of Diseases in Childhood, 88: 584–586.
22
layout Safe Water.indd 44
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:55
DeVivo MJ, Sekar P (1997) Prevention of spinal cord injuries that occur in swimming pools. Spinal Cord,
35(8): 509–515.
Dietz PE, Baker SP (1974) Drowning. Epidemiology and prevention. American Journal of Public Health,
64(4): 303–312.
EEA/WHO (1999) Water resources and human health in Europe. European Environment Agency and World
Health Organization Regional Office for Europe.
Gabrielsen JL, ed. (1988) Diving safety: a position paper. Indianapolis, IN, United States Diving.
Gomez-Juarez M, Cascales P, Garcia-Olmo D, Gomez-Juarez F, Usero S, Capilla P, Garcia-Blazquez E,
Anderica F (2001) Complete evisceration of the small intestine through a perianal wound as a result of
suction at a wading pool. Journal of Trauma, 51: 398–399.
Hill V (1984) History of diving accidents. In: Proceedings of the New South Wales Symposium on Water Safety.
Sydney, New South Wales, Department of Sport and Recreation, pp. 28–33.
Howland J, Hingson R (1988) Alcohol as a risk factor for drowning: a review of the literature (1950–
1985). Accident Analysis and Prevention, 20: 19–25.
Howland J, Hingson R, Mangione TW, Bell N, Bak S (1996) Why are most drowning victims men? Sex
difference in aquatic skills and behaviours. American Journal of Public Health, 86(1): 93–96.
Hultman CS, Morgan R (1994) Transanal intestinal evisceration following suction from an uncovered
swimming pool drain: case report. Journal of Trauma, 37(5): 843–847.
Kyriacou DN, Arcinue EL, Peek C, Kraus JF (1994) Effect of immediate resuscitation on children with
submersion injury. Pediatrics, 94: 137–142.
Levin DL, Morris FC, Toro LO, Brink LW, Turner G (1993) Drowning and near-drowning. Pediatric Clinics in North America, 40: 321–336.
Liller KD, Kent AB, Arcari C, MacDermott RJ (1993) Risk factors for drowning and near-drowning
among children in Hillsborough County, Florida. Public Health Reports, 108(3): 346–353.
Mackie I (1978) Alcohol and aquatic disasters. Medical Journal of Australia, 1(12): 652–653.
Mackie I (2005) Availability and quality of data to assess the global burden of drowning. In: Bierens JJLM
et al., eds. Handbook on drowning. Prevention, rescue and treatment. Netherlands, Springer, in press.
Mennen U (1981) A survey of spinal injuries from diving. A study of patients in Pretoria and Cape Town.
South African Medical Journal, 59(22): 788–790.
Milliner N, Pearn J, Guard R (1980) Will fenced pools save lives? A 10-year study from Mulgrave Shire,
Queensland. Medical Journal of Australia, 2: 510–511.
Minaire P, Demolin P, Bourret J, Girard R, Berard E, Deidier C, Eyssette M, Biron A (1983) Life expectancy following spinal cord injury: a ten-years survey in the Rhone-Alpes Region, France, 1969–1980.
Paraplegia, 21(1): 11–15.
National Center for Health Statistics (1998) National mortality data, 1997. Hyattsville, MD, Centers for
Disease Control and Prevention.
Nichter MA, Everett PB (1989) Childhood near-drowning: is cardiopulmonary resuscitation always indicated? Critical Care Medicine, 17(10): 993–995.
Orlowski JP (1989) It’s time for pediatricians to “rally round the pool fence”. Pediatrics, 83: 1065–1066.
Patetta MJ, Biddinger PW (1988) Characteristics of drowning deaths in North Carolina. Public Health
Reports, 103(4): 406–411.
Pearn J, Nixon J (1977) Prevention of childhood drowning accidents. Medical Journal of Australia, 1(17):
616–618.
Pearn J, Nixon J, Wilkey I (1976) Freshwater drowning and near-drowning accidents involving children: A
five-year total population study. Medical Journal of Australia, 2(25–26): 942–946.
CHAPTER 2.
layout Safe Water.indd 45
DROWNING AND INJURY PREVENTION
23
24.2.2006 9:56:56
Peden M, McGee K (2003) The epidemiology of drowning worldwide. Injury Control and Safety Promotion, 10(4): 195–199.
Pepe P, Bierens J (2005) Resuscitation: an overview. In: Bierens JJLM et al., eds. Handbook on drowning.
Prevention, rescue and treatment. Netherlands, Springer, in press.
Perrine MW, Mundt JC, Weiner RI (1994) When alcohol and water don’t mix: diving under the influence.
Journal of Studies on Alcohol, 55(5): 517–524.
Petridou E (2005) Risk factors for drowning and near-drowning injuries. In: Bierens JJLM et al., eds.
Handbook on drowning. Prevention, rescue and treatment. Netherlands, Springer, in press.
Plueckhahn VD (1979) Drowning: community aspects. Medical Journal of Australia, 2(5): 226–228.
Porter ES, Kohlstadt IC, Farrell KP (1997) Preventing wading pool suction-drain injuries. Maryland Medical Journal, 46(6): 297–298.
Present P (1987) Child drowning study: A report on the epidemiology of drowning in residential pools to children under age 5. Washington, DC, United States Consumer Product Safety Commission, Directorate for
Epidemiology.
Press E (1991) The health hazards of saunas and spas and how to minimize them. American Journal of
Public Health, 81(8): 1034–1037.
Quan L, Gore EJ, Wentz K, Allen J, Novack AH (1989) Ten year study of pediatric drownings and near
drownings in King County, Washington: lessons in injury prevention. Pediatrics, 83(6): 1035–1040.
Ryan CA, Dowling G (1993) Drowning deaths in people with epilepsy. Canadian Medical Association
Journal, 148(3): 270.
Sibert JR, Lyons RA, Smith BA, Cornall P, Sumner V, Craven MA, Kemp AM on behalf of the Safe Water Information Monitor Collaboration (2002) Preventing deaths by drowning in children in the United Kingdom: have
we made progress in 10 years? Population based incidence study. British Medical Journal, 324: 1070–1071.
Smith GS (2005) The global burden of drowning. In: Bierens JJLM et al., eds. Handbook on drowning.
Prevention, rescue and treatment. Netherlands, Springer, in press.
Spyker DA (1985) Submersion injury. Epidemiology, prevention and management. Pediatric Clinics of
North America, 32(1): 113–125.
Steinbruck K, Paeslack V (1980) Analysis of 139 spinal cord injuries due to accidents in water sport.
Paraplegia, 18(2): 86–93.
Stevenson MR, Rimajova M, Edgecombe D, Vickery K (2003) Childhood drowning: barriers surrounding
private swimming pools. Pediatrics, 111(2): e115–e119.
Stover SL, Fine PR (1987) The epidemiology and economics of spinal cord injury. Paraplegia, 25(3):
225–228.
Tator CH, Edmonds VE (1986) Sports and recreation are a rising cause of spinal cord injury. Physician and
Sportsmedicine, 14: 157–167.
Tator CH, Edmonds VE, Lapeczak X (1993) Ontario Catastrophic Sports Recreational Injuries Survey.
July 1, 1991 – July 30, 1992. Toronto, Ontario, Think First Canada.
Think First Foundation (2004) Think First Foundation website (http://www.thinkfirst.org/news/facts.html),
accessed 2 March 2004.
Thompson DC, Rivara FP (2000) Pool fencing for preventing drowning in children. Cochrane Database of
Systematic Reviews, 2: CD001047.
WHO (2003) Guidelines for safe recreational water environments. Vol. 1: Coastal and fresh waters. Geneva,
World Health Organization.
WHO (2004) The World Health Report 2004: Changing history. Geneva, World Health Organization.
Wintemute GJ, Kraus JF, Teret SP, Wright M (1987) Drowning in childhood and adolescence: a population-based study. American Journal of Public Health, 77: 830–832.
24
layout Safe Water.indd 46
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:56
World Congress on Drowning (2002) Recommendations. In: Proceedings of the World Congress on Drowning.
Amsterdam, 26–28 June 2002.
Yanai T, Hay JG, Gerot JT (1996) Three dimensional videography of swimming with panning periscopes.
Journal of Biomechanics, 33(5): 246–249.
CHAPTER 2.
layout Safe Water.indd 47
DROWNING AND INJURY PREVENTION
25
24.2.2006 9:56:56
CHAPTER 3
Microbial hazards
A
variety of microorganisms can be found in swimming pools and similar recreational water environments, which may be introduced in a number of ways.
In many cases, the risk of illness or infection has been linked to faecal contamination of the water. The faecal contamination may be due to faeces released by bathers or
a contaminated source water or, in outdoor pools, may be the result of direct animal
contamination (e.g. from birds and rodents). Faecal matter is introduced into the water
when a person has an accidental faecal release – AFR (through the release of formed
stool or diarrhoea into the water) or residual faecal material on swimmers’ bodies is
washed into the pool (CDC, 2001a). Many of the outbreaks related to swimming
pools would have been prevented or reduced if the pool had been well managed.
Non-faecal human shedding (e.g. from vomit, mucus, saliva or skin) in the swimming pool or similar recreational water environments is a potential source of pathogenic organisms. Infected users can directly contaminate pool or hot tub waters and
the surfaces of objects or materials at a facility with pathogens (notably viruses or
fungi), which may lead to skin infections in other patrons who come in contact with
the contaminated water or surfaces. ‘Opportunistic pathogens’ (notably bacteria) can
also be shed from users and transmitted via surfaces and contaminated water.
Some bacteria, most notably non-faecally-derived bacteria (see Section 3.4), may
accumulate in biofilms and present an infection hazard. In addition, certain freeliving aquatic bacteria and amoebae can grow in pool, natural spa or hot tub waters,
in pool or hot tub components or facilities (including heating, ventilation and airconditioning [HVAC] systems) or on other wet surfaces within the facility to a point
at which some of them may cause a variety of respiratory, dermal or central nervous
system infections or diseases. Outdoor pools may also be subject to microorganisms
derived directly from pets and wildlife.
This chapter describes illness and infection associated with microbial contamination of swimming pools, natural spas and hot tubs. The sections reflect the origin of
the microbial contaminant, as illustrated in Figure 3.1. In each case, a short subsection on risk assessment and risk management is given, although general management
strategies for managing air and water quality are described in detail in Chapter 5.
In most cases, monitoring for potential microbial hazards is done using indicator
microorganisms (rather than specific microbial pathogens), which are easy to enumerate and would be expected to be present in greater numbers than pathogens. The
traditional role of indicator parameters was to show the presence or absence of faecal
pollution in water supplies. The criteria associated with microbial indicators of pollution are outlined in Box 3.1 and further discussed in WHO (2004). The use of these
microorganisms in monitoring water quality is covered in Chapter 5.
26
layout Safe Water.indd 48
24.2.2006 9:56:56
Microorganism
hazard
Faecally-derived
Non-faecally-derived
Viruses
Bacteria
Bacteria
Viruses
Adenoviruses
Hepatitis A
Noroviruses
Enteroviruses
Shigella spp.
E. coli 0157
Legionella spp.
Pseudomonas spp.
Mycobacterium spp.
Staphylococcus aureus
Leptospira spp.
Molluscipoxvirus
Papillomavirus
Adenoviruses
Protozoa
Giardia
Cryptosporidium
Protozoa
Fungi
Trichophyton spp.
Epidermophyton floccosum
Naegleria fowleri
Acanthamoeba spp.
Plasmodium spp.
Figure 3.1. Potential microbial hazards in pools and similar environments
BOX 3.1 CRITERIA FOR INDICATOR ORGANISMS AND THEIR APPLICATION TO POOLS AND
SIMILAR ENVIRONMENTS
• The indicator should be absent in unpolluted environments and present when the source of pathogenic microorganisms of concern is present (e.g. faecal material).
• The indicator should not multiply in the environment.
• The indicator should be present in greater numbers than the pathogenic microorganisms.
• The indicator should respond to natural environmental conditions and water treatment processes
in a manner similar to the pathogens of concern.
• The indicator should be easy to isolate, identify and enumerate.
• Indicator tests should be inexpensive, thereby permitting numerous samples to be taken (if appropriate).
Microorganisms that are used to assess the microbial quality of swimming pool and similar environments include heterotrophic plate count – HPC (a general measure of non-specific microbial levels),
faecal indicators (such as thermotolerant coliforms, E. coli), Pseudomonas aeruginosa, Staphylococcus
aureus and Legionella spp. HPC, thermotolerant coliforms and E. coli are indicators in the strict sense
of the definition.
As health risks in pools and similar environments may be faecal or non-faecal in origin, both faecal indicators and non-faecally-derived microorganisms (e.g. P. aeruginosa, S. aureus and Legionella
spp.) should be examined. Faecal indicators are used to monitor for the possible presence of faecal
contamination; HPC, Pseudomonas aeruginosa and Legionella spp. can be used to examine growth, and
Staphylococcus aureus can be used to determine non-faecal shedding. The absence of these organisms, however, does not guarantee safety, as some pathogens are more resistant to treatment than the
indicators, and there is no perfect indicator organism.
CHAPTER 3.
layout Safe Water.indd 49
MICROBIAL HAZARDS
27
24.2.2006 9:56:57
3.1 Faecally-derived viruses
3.1.1 Hazard identification
The viruses that have been linked to swimming pool outbreaks are shown in
Table 3.1. Viruses cannot multiply in water, and therefore their presence must be a
consequence of pollution. Some adenoviruses may also be shed from eyes and the
throat and are responsible for swimming pool conjunctivitis.
Viruses of six types (rotavirus, norovirus, adenovirus, astrovirus, enterovirus and
hepatitis A virus) are all shed following infection. Clinical data show that rotaviruses
are by far the most prevalent cause of viral gastroenteritis in children, and noroviruses
cause the most cases of viral diarrhoea in adults. However, few waterborne pool outbreaks have been associated with these agents. Although outbreaks are highlighted, it
should be kept in mind that non-outbreak disease is likely to occur and that virus-associated pool or hot tub outbreaks are very uncommon. Even when outbreaks are
detected, the evidence linking the outbreak to the pool is generally circumstantial. In
the outbreaks summarized in Table 3.1, the etiological agents were detected in the
water in only two cases (D’Angelo et al., 1979; Papapetropoulou & Vantarakis, 1998).
3.1.2 Outbreaks of viral illness associated with pools
1. Adenovirus-related outbreaks
There are over 50 types of adenoviruses (Hunter, 1997), and while some may cause
enteric infections and are therefore shed in faeces, they are also associated with respiratory and ocular symptoms and non-faecally-derived transmission. Types 40 and 41
cause gastroenteritis in young children, but there is no documented association with
waterborne transmission.
Foy et al. (1968) reported an outbreak of pharyngo-conjunctival fever caused by
adenovirus type 3. The infection occurred in two children’s swimming teams after
exposure to unchlorinated swimming pool water. The attack rates in the two teams
were 65% and 67%, respectively. The main symptoms were fever, pharyngitis and
conjunctivitis. The virus could not be isolated from the pool water. The authors speculated that faecal contamination of the unchlorinated swimming pool water could
have been the source of the contamination.
Caldwell et al. (1974) reported an outbreak of conjunctivitis associated with adenovirus type 7 in seven members of a community swimming team. The main symptoms were associated with the eyes. An investigation of the pool-related facilities suggested that the school swimming pool was the source of the infection, as both the
pool chlorinator and pool filter had failed. The outbreak was brought under control
by raising the pool’s free residual chlorine level above 0.3 mg/l.
Adenovirus type 4 was the causative agent of a swimming pool-related outbreak of
pharyngo-conjunctivitis reported by D’Angelo et al. (1979). A total of 72 cases were
identified. Adenovirus type 4 was isolated from 20 of 26 swab specimens. The virus
was also detected in samples of pool water. An investigation showed that inadequate
levels of chlorine had been added to the pool water, resulting in no free chlorine
in pool water samples. Adequate chlorination and closing the pool for the summer
stopped the outbreak of illness.
28
layout Safe Water.indd 50
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:57
Table 3.1. Summary of waterborne disease outbreaks associated with pools due to faecallyexcreted viruses
Etiological
agent
Adenovirus 3
Source of agent
Possible faecal
contamination
Disinfection/
treatment
None
Reference
Foy et al., 1968
Adenovirus 7
Unknown
Improper chlorination
Caldwell et al., 1974
Adenovirus 4
Unknown
Inadequate chlorine level
D’Angelo et al., 1979
Adenovirus 3
Unknown
Pool filter system defect,
failed chlorinator
Martone et al., 1980
Adenovirus 7a
Unknown
Malfunctioning chlorinator
Turner et al., 1987
Adenoviruses
Unknown
Inadequate chlorination
Papapetropoulou &
Vantarakis, 1998
Adenovirus 3
Unknown
Inadequate chlorination and
pool maintenance
Harley et al., 2001
Hepatitis A
Accidental faecal
release suspected
None
Solt et al., 1994
Cross-connection
to sewer line
Operating properly
Mahoney et al., 1992
Unknown
Chlorinator disconnected
Kappus et al., 1982
Probably via public
toilets
Manual chlorination three
times a week
Maunula et al., 2004
No details available
No details available
Yoder et al., 2004
Norovirus
Echovirus 30
No details available
No details available
Yoder et al., 2004
Possible faecal
contamination
Chlorination failure
CDC, 2004
Vomit
Operating properly
Kee et al., 1994
A second outbreak in the same locality and year was linked to adenovirus type 3
and swimming activity (Martone et al., 1980). Based on surveys, at least 105 cases
were identified. The illness was characterized by sore throat, fever, headache and anorexia. Conjunctivitis affected only 34 of the individuals. Use of a swimming pool
was linked to the illness. The outbreak coincided with a temporary defect in the pool
filter system and probably improper maintenance of chlorine levels. The authors suspected that the level of free chlorine in the pool water was less than 0.4 mg/l. They
also pointed out that while the virus was probably transmitted through water, personto-person transmission could not be ruled out.
In 1987, an outbreak of adenovirus type 7a infection was associated with a swimming pool (Turner et al., 1987). Seventy-seven individuals were identified with the
symptoms of pharyngitis (inflammation of the pharynx). A telephone survey indicated that persons who swam at the community swimming pool were more likely to
be ill than those who did not. Swimmers who reported swallowing water were more
CHAPTER 3.
layout Safe Water.indd 51
MICROBIAL HAZARDS
29
24.2.2006 9:56:57
likely to be ill than those who did not. Further investigation showed that the pool
chlorinator had reportedly malfunctioned during the period when the outbreak occurred. The outbreak ceased when proper chlorination was reinstated.
An outbreak of pharyngo-conjunctivitis caused by adenoviruses occurred among
swimmers participating in a competition. Over 80 people were found to be suffering
from symptoms. Adenoviruses were identified in swimming pool samples using nested
polymerase chain reaction, and poor chlorination (residual chlorine levels <0.2 mg/l) was
considered to have contributed to the outbreak (Papapetropoulou & Vantarakis, 1998).
In 2000, an outbreak of illness related to adenovirus type 3 was detected. It was
found that there was a strong association between the presence of symptoms and
swimming at a school camp. Although adenoviruses were not isolated from the pool
water, inspection of the pool revealed that it was poorly maintained and inadequately
chlorinated (Harley et al., 2001).
2. Hepatitis A-related outbreaks
Solt et al. (1994) reported an outbreak in Hungary in which 31 children were hospitalized following hepatitis A infection. Investigation of potential common sources
eliminated food, drink and person-to-person transmission. All of the patients had
reported swimming at a summer camp swimming pool. Further investigation discovered 25 additional cases. All of the cases were males between the ages of 5 and
17 years. The pool, which was not chlorinated, was half full of water for a period and
was used by younger children. The pool was generally overcrowded during the month
of August. It was concluded that the crowded conditions and generally poor hygienic
conditions contributed to the outbreak.
An outbreak of hepatitis A in several states in the USA during 1989, which may
have been associated with a public swimming pool, was reported by Mahoney et al.
(1992). Twenty of 822 campers developed hepatitis A infections. Case–control studies indicated that swimmers or those who used a specific hot tub were more likely than
controls to become ill. It was hypothesized that a cross-connection between a sewage
line and the pool water intake line may have been responsible for the outbreak or that
one of the swimmers may have contaminated the water. The disinfectant levels in the
pools met local standards.
3. Norovirus-related outbreaks
Few outbreaks of norovirus-related disease (previously known as Norwalk virus or
Norwalk-like viruses) associated with swimming pools have been reported. Kappus et
al. (1982) reported an outbreak of norovirus gastroenteritis associated with a swimming
pool that affected 103 individuals. The illness typically lasted 24 h and was characterized
by vomiting and cramping. Serological studies suggested that norovirus was the cause
of the gastroenteritis among the swimmers. Case–control studies indicated that swimmers were more likely than non-swimmers to become ill. Similarly, the attack rate was
significantly higher in swimmers who had swallowed water than in those who had not.
The pool chlorinator had not been reconnected before the outbreak, which occurred at
the beginning of the swimming season. The source of the virus was not found.
Maunula et al. (2004) reported an outbreak of gastroenteritis associated with norovirus contracted from a wading pool in Helsinki, Finland. Norovirus and astrovirus
were isolated from water samples taken from the pool. The pool was heavily used
30
layout Safe Water.indd 52
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:57
during the summer months (with as many as 500 bathers a day) and was manually
chlorinated three times a week. There was no routine monitoring of free chlorine. It
is believed that the pool had been heavily contaminated with human faecal material,
with the contamination apparently being carried from the public toilets, situated very
close to the pool, which were found to be grossly contaminated (although a number
of nappies were also found at the bottom of the pool during the cleaning operation).
The pool was emptied and cleaned and subsequently fitted with continuous filtration
and chlorination.
Yoder et al. (2004) reported two outbreaks of norovirus infection that were associated with swimming pools in the USA between 2000 and 2002, one of which was
associated with a hotel pool and hot tub, but gave no other details.
CDC (2004) reported an outbreak of gastroenteritis in children, whose only common exposure was attendance at a swimming club the previous weekend. Fifty-three
people reported illness, and norovirus was isolated from a number of cases. An undetected accidental faecal release was suspected, and poor pool water quality monitoring
and maintenance contributed to the outbreak.
4. Enterovirus-related outbreaks
Enteroviruses include polioviruses, echoviruses and coxsackieviruses types A and
B. The only documented case of enterovirus infection following pool exposure was
associated with echovirus, as reported by Kee et al. (1994). Thirty-three bathers had
symptoms of vomiting, diarrhoea and headache shortly after swimming in an outdoor
swimming pool. The outbreak is believed to have been caused by a bather who swam
while ill and vomited into the pool. Individuals who had swallowed water were more
likely to become ill than those who had not. Echovirus 30 was isolated from the
case who had vomited and from six other cases. Proper disinfectant levels had been
maintained at the pool, but they were inadequate to contain the risk of infection from
vomit in the pool water.
3.1.3 Risk assessment
Determination of polluted pool water as the unequivocal cause of a viral disease
outbreak requires the detection of the virus in a water sample. This is clearly not a
routine procedure, but is something that is done in response to a suspected disease
outbreak. Concentration techniques for viruses in water are available (e.g. SCA, 1995
and reviewed by Wyn-Jones & Sellwood, 2001), which may be adapted to pool water
samples. Some agents (e.g. enteroviruses) may be detected in cell culture, but most
(e.g. adenoviruses 40 and 41 and noroviruses) require molecular detection methods.
If the virus has remained in contact with water containing free disinfectant for some
time, then detection of infectious virus may not be possible.
Enteric viruses occur in high numbers in the faeces of infected individuals. Hepatitis A virus has been found at densities of 1010 per gram (Coulepis et al., 1980), and
noroviruses have been estimated at 1011 per gram, although echoviruses may reach
only 106 per gram. Given the high densities at which some viruses can be shed by
infected individuals, it is not surprising that accidental faecal releases into swimming
pools and hot tubs can lead to high attack rates in pools where outbreaks occur, especially if the faecal release is undetected or detected but not responded to adequately.
CHAPTER 3.
layout Safe Water.indd 53
MICROBIAL HAZARDS
31
24.2.2006 9:56:57
1. Adenoviruses
Most adenoviruses can be grown in commonly available cell cultures, with the exception of types 40 and 41, which may be detected by molecular biological techniques,
principally by the polymerase chain reaction – PCR (Kidd et al., 1996). Types 40 and
41 are those usually associated with gastroenteritis. Other types, though more usually
associated with infections of the eyelids and/or throat (pharyngo-conjunctival fever),
may also be shed in the faeces for extended periods (Fox et al., 1969). The attack rate
for swimming pool outbreaks linked to adenovirus serotypes is moderately high, ranging from 18% to 52% (Martone et al., 1980; Turner et al., 1987).
2. Hepatitis A virus
Culture of hepatitis A virus is generally impractical, and detection relies on molecular
methods (reverse transcriptase polymerase chain reaction – RT-PCR). The virus is
transmitted by the faecal–oral route, with water and sewage being a frequent source of
infection. The disease has an incubation period of 15–50 days, anorexia, nausea, vomiting and often jaundice being the common symptoms. Virus is shed before the onset
of symptoms. The attack rate in one outbreak of illness associated with a swimming
pool ranged from 1.2% to 6.1% in swimmers less than 18 years of age (Mahoney et
al., 1992).
3. Noroviruses
Environmental detection of these agents is restricted to RT-PCR since there is no
cell culture system available. Symptoms occur within 48 h of exposure and include
diarrhoea, vomiting, nausea and fever. Virus shedding, as detected by electron microscopy, stops soon after onset of symptoms, but is detectable by RT-PCR for up to five
days. Attack rates are generally very high; Kappus et al. (1982), for example, reported
an attack rate of 71% for those swimmers who had swallowed water.
4. Enteroviruses
Coxsackieviruses are frequently found in polluted waters, and vaccine poliovirus is
also found where there is a high percentage of individuals immunized (although no
investigations have been reported where this has been found in pool water). Echoviruses are found less often. None of the enteroviruses commonly cause gastroenteritis
in the absence of other disease, and, although they are associated with a wide variety
of symptoms, most infections are asymptomatic.
3.1.4 Risk management
The control of viruses in swimming pool water and similar environments is usually
accomplished by proper treatment, including the application of disinfectants. Episodes of gross contamination of a swimming pool due to an accidental faecal release or
vomit from an infected person cannot be effectively controlled by normal disinfectant
levels. The only approach to maintaining public health protection under conditions
of an accidental faecal release or vomit is to prevent the use of the pool until the
contaminants are inactivated (see Chapter 5). The education of parents/caregivers
of small children and other water users about good hygienic behaviour at swimming
pools is another approach that may prove to be useful for improving health safety at
32
layout Safe Water.indd 54
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:58
swimming pools and the reduction of accidental faecal releases. It is recommended
that people with gastroenteritis should not use public or semi-public pools and hot
tubs while ill or for at least a week after their illness, in order to avoid transmitting the
illness to other pool or hot tub users.
3.2 Faecally-derived bacteria
3.2.1 Hazard identification
Shigella species and Escherichia coli O157 are two related bacteria that have been
linked to outbreaks of illness associated with swimming in pools or similar environments. Shigella has been responsible for outbreaks related to artificial ponds and other
small bodies of water where water movement has been very limited. The lack of water
movement means that these water bodies behave very much as if they were swimming
pools, except that chlorination or other forms of disinfection are not being used.
Similar non-pool outbreaks have been described for E. coli O157, although there have
also been two outbreaks reported where the source was a children’s paddling pool.
These outbreaks are summarized in Table 3.2, as they illustrate the potential risk that
might be experienced in swimming pools under similar conditions, although only the
pool specific outbreaks are covered in detail.
3.2.2 Outbreaks of bacterial illness associated with pools
1. Shigella-related outbreaks
An outbreak of shigellosis associated with a fill-and-drain wading pool (filled on a
daily basis with potable water) was reported from Iowa, USA (CDC, 2001b). The
pool, which had a maximum depth of 35 cm, was frequented by very young and nontoilet-trained children. The pool had neither recirculation nor disinfection. One pool
sample was found to contain thermotolerant coliforms and E. coli. Sixty-nine people
were considered to be infected with shigellosis, of which 26 cases were laboratory
confirmed as S. sonnei. It is thought that the transmission of shigellosis over several
days may have been a result of residual contaminated water present after draining and
people with diarrhoea visiting the pool on subsequent days.
2. E. coli O157-related outbreaks
In 1992, an outbreak of E. coli O157 infection was epidemiologically and clinically
linked to a collapsible children’s paddling pool (Brewster et al., 1994). Six cases of
diarrhoea, including one case of haemolytic uraemic syndrome, and one asymptomatic case were identified. E. coli O157 phage type 59 was isolated from the six cases.
The pool had not been drained or disinfected over the three-day period surrounding
the outbreak. It was believed that the pool had been initially contaminated by a child
known to have diarrhoea.
In 1993, six children with haemorrhagic colitis, three of whom developed haemolytic uraemic syndrome, were epidemiologically linked to a disinfected public paddling pool (Hildebrand et al., 1996). E. coli O157 phage type 2 was isolated from
faecal specimens of five cases. E. coli (but not E. coli O157) was detected in the pool
during the investigation. Free chlorine levels in the pool were less than 1 mg/l at the
time of sampling.
CHAPTER 3.
layout Safe Water.indd 55
MICROBIAL HAZARDS
33
24.2.2006 9:56:58
Table 3.2. Summary of outbreaks of disease associated with pools due to faecally-excreted bacteria
Etiological agent
Source of agent
Disinfection/
treatment
Reference
Shigella spp.
AFR
Not known
AFR
Likely AFR
None
None
None
None
Sorvillo et al., 1988
Makintubee et al., 1987
Blostein, 1991
CDC, 2001b
E. coli O157
AFR
AFR
AFR
None
Not known
Inadequate
treatment
None
None
Keene et al., 1994
Brewster et al., 1994
Hildebrand et al., 1996
Not known
Not known
CDC, 1996
Cransberg et al., 1996
AFR – Accidental faecal release
3.2.3 Risk assessment
Shigella species are small, non-motile, Gram-negative, facultatively anaerobic rods. They
ferment glucose but not lactose, with the production of acid but not gas. Symptoms associated with shigellosis include diarrhoea, fever and nausea. The incubation period for
shigellosis is 1–3 days. The infection usually lasts for 4–7 days and is self-limiting.
E. coli O157 are small, motile, non-spore-forming, Gram-negative, facultatively
anaerobic rods. They ferment glucose and lactose. Unlike most E. coli, E. coli O157
does not produce glucuronidase, nor does it grow well at 44.5 °C. E. coli O157 causes
non-bloody diarrhoea, which can progress to bloody diarrhoea and haemolytic uraemic syndrome. Other symptoms include vomiting and fever in more severe cases. The
usual incubation period is 3–4 days, but longer periods are not uncommon. In most
instances, the illness typically resolves itself in about a week. About 5–10% of individuals develop haemolytic uraemic syndrome following an E. coli O157 infection.
Haemolytic uraemic syndrome, characterized by haemolytic anaemia and acute renal
failure, occurs most frequently in infants, young children and elderly people.
Individuals infected with E. coli O157 shed these bacteria at similar or slightly
higher densities than the non-enterohaemorrhagic Shigella. Literature reports indicate
that E. coli O157 is known to be shed at densities as high as 108 per gram. Shigella species are shed at similar but somewhat lower levels by individuals who have contracted
shigellosis (Table 3.3).
Table 3.3. Bacterial exposure factors
Agent
Density shed
during infection
6
Duration of
shedding
Infective
dose
2
Reference
Shigella
10 per gram
30 days
<5 × 10 /ID50
Makintubee et al., 1987;
DuPont, 1988
Escherichia
coli O157
108 per gram
7–13 days
Not knowna
Pai et al., 1984
ID50 – dose of microorganisms required to infect 50% of individuals exposed
a
Probably similar to Shigella
34
layout Safe Water.indd 56
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:58
The infective dose for Shigella species is usually between 10 and 100 organisms
(Table 3.3). Lower doses, however, may cause illness in infants, the elderly or immunocompromised individuals. The infective dose for E. coli O157 is unknown but is
likely to be similar to that for Shigella species. Keene et al. (1994) suggested that the
infective dose is very low, based on experience in an outbreak.
3.2.4 Risk management
One of the primary risk management interventions is to reduce accidental faecal
release occurrence in the first place – for example, by educating pool users. E. coli O157
and Shigella species are readily controlled by chlorine and other disinfectants under
ideal conditions. However, if an accidental faecal release has occurred in a swimming
pool or hot tub, it is likely that these organisms will not be instantly eliminated, and
other steps will have to be taken to provide time for disinfectant effect, such as evacuation of the pool (see Chapter 5).
3.3 Faecally-derived protozoa
3.3.1 Hazard identification
Giardia and particularly Cryptosporidium spp. are faecally-derived protozoa that have
been linked to outbreaks of illness in swimming pools and similar environments.
These two organisms are similar in a number of respects. They have a cyst or oocyst
form that is highly resistant to both environmental stress and disinfectants, they have
a low infective dose and they are shed in high densities by infected individuals. There
have been a number of outbreaks of disease attributed to these pathogens, as summarized in Table 3.4.
3.3.2 Outbreaks of protozoan illness associated with pools
1. Giardia-related outbreaks
Giardiasis has been associated with swimming pools and water slides. In 1994, a case–
control study was conducted in the United Kingdom to determine the risk factors
for giardiasis. Giardiasis cases were identified from disease surveillance reports over
a one-year period (Gray et al., 1994). Seventy-four cases and 108 matched controls
were identified. Analysis of the data indicated that swimming appeared to be an independent risk factor for giardiasis. Other recreational exposures and ingestion of potentially contaminated water were found to be not significantly related to giardiasis.
In 1984, a case of giardiasis was reported in a child who had participated in an
infant and toddler swim class in Washington State, USA (Harter et al., 1984). The
identification of this case of giardiasis led to a stool survey of 70 of the class participants. The stool survey revealed a 61% prevalence of Giardia infection. None of the
non-swimming playmates was positive. Eight of 23 children (35%) exposed only at
a better maintained pool to which the classes had been moved four weeks prior to
the survey were positive. The investigators did not find any evidence of transmission
to non-swim-class pool users. Adequate chlorine levels were maintained in the pool.
Contamination of the pool was thought to be due to an undetected accidental faecal
release.
CHAPTER 3.
layout Safe Water.indd 57
MICROBIAL HAZARDS
35
24.2.2006 9:56:58
Table 3.4. Summary of disease outbreaks associated with pools due to faecally-derived protozoa
Etiological
agent
Source of agent
Disinfection/
treatment
Reference
Giardia
AFR
AFR
AFR
Inadequate treatment
Inadequate treatment
Adequate treatment
Harter et al., 1984
Porter et al., 1988
Greensmith et al., 1988
Cryptosporidium
AFR
Sewage intrusion
AFR
Sewage intrusion
Not known
AFR
AFR
Likely AFR
AFR
Not known
Adequate treatment
Plumbing defects
Not known
Not known
Not known
Adequate treatment
Adequate treatment
Adequate treatment
Faulty ozone generator
Plumbing and treatment
defects
Adequate treatment
Treatment problems
Adequate treatment
Inadequate treatment
Adequate treatment
Adequate treatment
Not known
Ozonation problems
Not known
Not known
CDC, 1990
Joce et al., 1991
Bell et al., 1993
McAnulty et al., 1994
CDC, 1994
Hunt et al., 1994
CDSC, 1995
Sundkist et al., 1997
CDSC, 1997
CDSC, 1998
Not known
Likely AFR
Suspected AFR
Likely AFR
Not known
Not known
Not known
Not known
AFR
Not known
CDSC, 1999
CDSC, 1999
CDSC, 2000
CDSC, 2000
CDSC, 2000
CDSC, 2000
CDSC, 2000
CDSC, 2000
CDC, 2001c
Galmes et al., 2003
AFR – accidental faecal release
Adequate treatment – in terms of indicator bacteria monitoring results
In the autumn of 1985, an outbreak of giardiasis occurred among several swimming groups at an indoor pool in north-east New Jersey, USA (Porter et al., 1988).
Nine clinical cases were identified, eight of whom had Giardia-positive stool specimens. All were female, seven were adults (>18 years), and two were children. A 39%
attack rate was observed for the group of women who had exposure on one day. These
cases had no direct contact with children or other risk factors for acquiring Giardia.
Infection most likely occurred following ingestion of swimming pool water contaminated with Giardia cysts. The source of Giardia contamination was a child who had a
faecal accident in the pool, who was a member of the group that swam the same day
as the women’s swimming group. A stool survey of the child’s group showed that of 20
people tested, 8 others were positive for Giardia. Pool records showed that no chlorine
measurements had been taken on the day of the accidental faecal release and that no
free chlorine level was detectable on the following day.
In 1988, an outbreak of giardiasis was associated with a hotel’s new water slide pool
(Greensmith et al., 1988). Among 107 hotel guests and visitors surveyed, 29 probable
and 30 laboratory-confirmed cases of Giardia infection were found. Cases ranged
36
layout Safe Water.indd 58
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:59
from 3 to 58 years of age. Symptoms in the 59 cases included diarrhoea, cramps,
foul-smelling stools, loss of appetite, fatigue, vomiting and weight loss. Significant
associations were found between illness and staying at the hotel, using the water slide
pool and swallowing pool water. A possible contributing factor was the proximity of
a toddlers’ pool, a potential source of faecal material, to the water slide pool. Water in
the slide pool was treated by sand filtration and bromine disinfection.
2. Cryptosporidium-related outbreaks
A number of outbreaks of cryptosporidiosis have been linked to swimming pools. The
sources of Cryptosporidium contaminating the pools were believed to be either sewage
or the swimmers themselves. A number of outbreaks are reviewed below.
In 1988, an outbreak of 60 cases of cryptosporidiosis was reported in Los Angeles
County, USA (CDC, 1990). Swimmers were exposed to pool water in which there
had been a single accidental faecal release. The attack rate was about 73%. The common factor linking infected individuals was use of the swimming pool.
In August 1988, the first outbreak of cryptosporidiosis associated with a swimming
pool in the United Kingdom was recognized following an increase in the number of
cases of cryptosporidiosis that had been identified by the Doncaster Royal Infirmary
microbiology laboratory (Joce et al., 1991). By October of that year, 67 cases had
been reported. An investigation implicated one of two pools at a local sports centre.
Oocysts were identified in the pool water. Inspection of the pool pipework revealed
significant plumbing defects, which had allowed ingress of sewage from the main
sewer into the circulating pool water. The epidemiological investigation confirmed
an association between head immersion and illness. The concentration of oocysts
detected in the pool water samples that were tested was 50 oocysts per litre. Difficulty
had been experienced in controlling the level of free chlorine residual, which implied
that disinfection was probably not maintained at an appropriate level.
An outbreak of cryptosporidiosis occurred in British Columbia, Canada, in 1990
(Bell et al., 1993). A case–control study and illness survey indicated that the transmission occurred in a public children’s pool at the local recreation centre. Analysis using
laboratory-confirmed cases showed that the illnesses were associated with swimming in
the children’s pool within two weeks before onset of illness. Attack rates ranged from
8% to 78% for various groups of children’s pool users. Several accidental faecal releases,
including diarrhoea, had occurred in the pool before and during the outbreak.
In 1992, public health officials in Oregon, USA, noted a large increase in the number
of stool specimens submitted for parasitic examination that were positive for Cryptosporidium (McAnulty et al., 1994). They identified 55 patients with cryptosporidiosis,
including 37 who were the first individuals ill in their households. A case–control study
involving the first 18 case patients showed no association between illness and day-care
attendance, drinking municipal drinking-water or drinking untreated surface waters.
However, 9 of 18 case patients reported swimming at the local wave pool, whereas none
of the controls indicated this activity. Seventeen case patients were finally identified as
swimming in the same pool. The investigators concluded that the outbreak of cryptosporidiosis was probably caused by exposure to faecally contaminated pool water.
In August 1993, a parent informed the Department of Public Health of Madison,
Wisconsin, USA, that her daughter was ill with a laboratory-confirmed Cryptosporidium infection and that members of her daughter’s swim team had severe diarrhoea
CHAPTER 3.
layout Safe Water.indd 59
MICROBIAL HAZARDS
37
24.2.2006 9:56:59
(CDC, 1994). Fifty-five per cent of 31 pool users interviewed reported having had
watery diarrhoea for two or more days. Forty-seven per cent of the 17 cases had had
watery diarrhoea for more than five days. A second cluster of nine cases was identified
later in the month. Seven of the nine reported swimming at a large outdoor pool.
Public health authorities cleaned the pool, shock dosed with chlorine and prohibited
people with diarrhoea from swimming in the pool.
In the UK, 18 outbreaks of cryptosporidiosis were associated with pools between
1989 and 1999. Recognized accidental faecal releases at the pool occurred in four of
the outbreaks, although faecal contamination was known or suspected in a further
five outbreaks. Outbreaks were associated with pools disinfected with chlorine and
with ozone and with both well and poorly managed pools (PHLS, 2000).
Two protracted outbreaks of cryptosporidiosis associated with swimming pools
were reported from Ohio and Nebraska, USA (CDC, 2001c). In both cases, accidental faecal releases (on more than one occasion) were observed. In the Nebraska
outbreak, 32% of cases reported swimming during their illness or shortly afterwards.
In Australia, a statewide outbreak of cryptosporidiosis in New South Wales was
associated with swimming at public pools (Puech et al., 2001). The association was
reported to be stronger for cases from urban areas. The authors noted that Cryptosporidium oocysts were more commonly detected from pools where at least two notified
cases had swum, and that outbreaks could involve multiple pools.
A large outbreak of cryptosporidiosis has been associated with a hotel in Majorca,
Spain, used by British tourists. The outbreak was detected in Scotland, following the
detection of cryptosporidiosis in tourists returning from Majorca. Almost 400 cases
were identified, and the outbreak was thought to be associated with the hotel swimming pool, with oocysts being detected in samples of the pool water (Galmes et al.,
2003). This outbreak resulted in guidelines on cryptosporidiosis prevention being
produced for the Spanish hoteliers association (Confederation Española de Hoteles
y Apartamentos Turisticos) and the UK Federation of Tour Operators (R. Cartwright,
pers. comm.).
In the USA, an analysis of recreationally-associated waterborne outbreaks of illness
between 2001 and 2002 was conducted (Yoder et al., 2004). Cryptosporidium species
were the most common cause of gastrointestinal outbreaks of illness associated with
treated swimming pool water.
3.3.3 Risk assessment
Giardia cysts are 4–12 µm in diameter. Viable cysts that are ingested by humans have
an incubation period of about 7–12 days. The resulting gastroenteritis is characterized
by diarrhoea with accompanying abdominal cramps. The illness lasts for about 7–10
days. Cryptosporidium oocysts are 4–6 µm in diameter and are much more resistant
to chlorine than Giardia cysts. If viable oocysts are ingested, there is an incubation
period of 4–9 days before symptoms appear. The illness lasts about 10–14 days, with
symptoms typically including diarrhoea, vomiting and abdominal cramps. In patients
with severely weakened immune systems, such as those with HIV infection and cancer
and transplant patients taking certain immune system-suppressing drugs, cryptosporidiosis is generally chronic and more severe than in immunocompetent people and
causes diarrhoea that can last long enough to be life threatening (Petersen, 1992).
38
layout Safe Water.indd 60
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:56:59
The Cryptosporidium infective dose that affects 50% of the challenged population
of humans is about 132 oocysts (DuPont et al., 1995), although this does depend
upon the strain (Okhuysen et al., 1999), and for some strains fewer than 100 oocysts
can lead to infection. The duration of shedding of these oocysts after infection is 1–2
weeks. The infection is self-limiting in most individuals, lasting 1–3 weeks. Cryptosporidium oocysts discharged by ill individuals are usually observed at densities of
106–107 per gram. The infective dose of Giardia that will cause gastroenteritis in 25%
of an exposed population is 25 cysts. Giardia cysts discharged in the faeces of infected
individuals are usually at densities of 3 × 106 per gram. The shedding of cysts can
persist for up to six months (Table 3.5).
Table 3.5. Protozoan exposure factors
Agent
Density shed
during infectiona
Duration of
shedding
Infective
dose
Cryptosporidium
106–107 per gram
1–2 weeks
132/ID50
Casemore, 1990;
DuPont et al., 1995
Giardia
3 × 106 per gram
6 months
25/ID25
Rendtorff, 1954;
Feachem et al., 1983
Reference
ID50 (ID25) – dose of microorganisms required to infect 50% (25%) of individuals exposed
a
Figures represent the peak and are not representative of the whole of the infection period
3.3.4 Risk management
Giardia cysts and Cryptosporidium oocysts are very resistant to many disinfectants, including chlorine (Lykins et al., 1990). Cryptosporidium, for example (the more chlorine resistant of the two protozoa), requires chlorine concentrations of 30 mg/l for 240 min (at
pH 7 and a temperature of 25 °C) for a 99% reduction to be achieved (i.e. an impractical
level). Inactivation of oocysts with chlorine is greater when ozone, chlorine dioxide or UV
irradiation is also used (Gregory, 2002). Ozone is a more effective disinfectant (compared
with chlorine) for the inactivation of Giardia cysts and Cryptosporidium oocysts. Cryptosporidium oocysts are sensitive to 5 mg of ozone per litre. Almost all (99.9%) of the oocysts
are killed after 1 min (at pH 7 and a temperature of 25 °C). Giardia cysts are sensitive to
0.6 mg of ozone per litre. Ninety per cent of the cysts are inactivated after 1 min (at pH 7
and a temperature of 5 °C). As ozone is not a residual disinfectant (i.e. it is not applied so
as to persist in pool water in use), sufficient concentration and time for inactivation must
be ensured during treatment before residual ozone removal and return to the pool.
It should be noted, however, that the figures above represent removal under laboratory (i.e. ideal) conditions. Additionally, studies have generally used oxidant demandfree water (i.e. they were not performed in simulated recreational water where additional organic material is present). Carpenter et al. (1999) found that the presence of
faecal material increased the Ct value (disinfectant concentration in mg/l multiplied
by time in minutes) needed to disinfect swimming pools.
UV is also effective at inactivating Giardia cysts and Cryptosporidium oocysts. A near
complete inactivation (99.9%) of Cryptosporidium occurs at UV exposures of 10 mJ/cm2
CHAPTER 3.
layout Safe Water.indd 61
MICROBIAL HAZARDS
39
24.2.2006 9:56:59
(WHO, 2004). Inactivation of Giardia cysts (99%) occurs at lower UV intensities of
5 mJ/cm2 (WHO, 2004). The efficacy of UV is impacted by particulate matter and the
growth of biofilms. Thus, turbidity should be low, and UV lamps need to be cleaned periodically to remove biofilms or other substances that interfere with UV light emission.
Like ozone, UV leaves no disinfectant residual and thus should be combined with chlorine or another disinfectant that remains in the water after treatment (WHO, 2004).
At present, the most practical approach to eliminating cysts and oocysts is through the
use of filtration. Cryptosporidium oocysts are removed by filtration where the porosity of
the filter is less than 4 µm. Giardia cysts are somewhat larger and are removed by filters
with a porosity of 7 µm or less, although statistics on removal efficiency during filtration
should be interpreted with caution. Removal and inactivation of cysts and oocysts occur
only in the fraction of water passing through treatment. Since a pool is a mixed and not a
plug flow system, the rate of reduction in concentration in the pool volume is slow.
Most outbreaks of giardiasis and cryptosporidiosis among pool swimmers have been
linked to pools contaminated by sewage, accidental faecal releases or suspected accidental
faecal releases. A study conducted in six pools in France, in the absence of detected faecal releases, found only a single instance when Cryptosporidium oocysts were detected
(Fournier et al., 2002). An Italian investigation of 10 chlorinated swimming pools found
Cryptosporidium and Giardia in 3% of pool water samples despite otherwise good water
quality (according to microbial monitoring results) and free chlorine levels of approximately 1 mg/l. In addition, both Cryptosporidium and Giardia were always detected in the
filter backwash water (Bonadonna et al., 2004). Pool maintenance and appropriate disinfection levels are easily overwhelmed by accidental faecal releases or sewage intrusion;
therefore, the only possible response to this condition, once it has occurred, is to prevent
use of the pool and physically remove the oocysts by draining or by applying a long period of filtration, as inactivation in the water volume (i.e. disinfection) is impossible (see
Chapter 5). However, the best intervention is to prevent accidental faecal releases from
occurring in the first place, through education of pool users about appropriate hygienic
behaviour. Immunocompromised individuals should be aware that they are at increased
risk of illness from exposure to pathogenic protozoa.
3.4 Non-faecally-derived bacteria
Infections and diseases associated with non-enteric pathogenic bacteria found in
swimming pools and similar recreational water environments are summarized in Table
3.6. A number of these bacteria may be shed by bathers or may be present in biofilms
(assemblages of surface-associated microbial cells enclosed in an extracellular matrix
– Donlan, 2002). Biofilms may form on the lining of pipes (for example) in contact
with water and may serve to protect the bacteria from disinfectants.
3.4.1 Legionella spp.
1. Risk assessment
Legionella are Gram-negative, non-spore-forming, motile, aerobic bacilli, which may
be free-living or living within amoebae and other protozoa or within biofilms. Legionella spp. are heterotrophic bacteria found in a wide range of water environments and
can proliferate at temperatures above 25 °C. They may be present in high numbers
in natural spas using thermal spring water, and they can also grow in poorly main40
layout Safe Water.indd 62
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:00
Table 3.6. Non-faecally-derived bacteria found in swimming pools and similar environments and
their associated infections
Organism
Infection/disease
Source
Legionella spp.
Legionellosis
(Pontiac fever and
Legionnaires’ disease)
Aerosols from natural spas, hot tubs
and HVAC systems
Poorly maintained showers or heated
water systems
Pseudomonas
aeruginosa
Folliculitis (hot tubs)
Swimmer’s ear (pools)
Bather shedding in pool and hot tub
waters and on wet surfaces around
pools and hot tubs
Mycobacterium spp.
Swimming pool granuloma
Hypersensitivity
pneumonitis
Bather shedding on wet surfaces
around pools and hot tubs
Aerosols from hot tubs and HVAC systems
Staphylococcus aureus
Skin, wound and ear infections Bather shedding in pool water
Leptospira spp.
Haemorrhagic jaundice
Aseptic meningitis
Pool water contaminated with
urine from infected animals
HVAC – heating, ventilation and air conditioning
tained hot tubs, associated equipment and HVAC systems. Legionella spp. can also
multiply on filter materials, namely granular activated carbon. However, exposure to
Legionella is preventable through the implementation of basic management measures,
including filtration, maintaining a continuous disinfectant residual in hot tubs (where
disinfectants are not used, there must be a high dilution rate with fresh water) and the
maintenance and physical cleaning of all natural spa, hot tub and pool equipment,
including associated pipes and air-conditioning units.
The risk of infection following exposure to Legionella is difficult to assess and
remains a matter of some debate (Atlas, 1999). Due to its prevalence in both natural
and artificial environments, it must be considered that people are frequently exposed
(at least to low numbers). Generally, there is no reaction to such exposure, asymptomatic production of antibodies or development of a mild flu-like illness, which may not
be attributed to Legionella infection.
Legionella spp. can cause legionellosis, a range of pneumonic and non-pneumonic
disease (WHO, 2005). Ninety per cent of cases of legionellosis are caused by L. pneumophila. Legionnaires’ disease is characterized as a form of pneumonia. General risk
factors for the illness include gender (males are roughly three times more likely than
females to contract Legionnaires’ disease), age (50 or older), chronic lung disease,
cigarette smoking and excess consumption of alcohol. Specific risk factors, in relation
to pools and hot tubs, include frequency of hot tub use and length of time spent in
or around hot tubs. Although the attack rate is often less than 1%, mortality among
hospitalized cases ranges widely up to 50%. Pontiac fever is a non-pneumonic, nontransmissible, non-fatal, influenza-like illness. The attack rate can be as high as 95%
in the total exposed population. Patients with no underlying illness or condition recover in 2–5 days without treatment.
CHAPTER 3.
layout Safe Water.indd 63
MICROBIAL HAZARDS
41
24.2.2006 9:57:00
Risk of legionellosis from pools and similar environments is associated with proliferation of Legionella in spas or hot tubs, associated equipment and HVAC systems.
The inference to be drawn from reported outbreaks and documented single cases is
that inhalation of bacteria, or aspiration following ingestion, during natural spa or
hot tub use may lead to disease, although Leoni et al. (2001) concluded that showers
may present a greater risk of legionellosis than pool water. Thermal spring waters,
especially, may be a source of high numbers of Legionella spp. (Bornstein et al., 1989;
Martinelli et al., 2001), and they have been implicated in cases of legionnaires’ disease
(Bornstein et al., 1989; Mashiba et al., 1993).
Piped drinking-water distribution systems, household hot and cold water maintained between 25 °C and 50 °C, cooling towers, evaporative condensers of air-conditioning devices, water fountains and mist-generating machines are also potential
sources of exposure to Legionella.
2. Risk management
Control of Legionella follows similar general principles to water safety plans applied to
drinking-water supplies (WHO, 2004), although, in this instance, the principal responsibility will not lie with the water supplier. Authorities responsible for regulation of recreational facilities should ensure the implementation of safety plans, and such plans should
address not only pools and hot tubs but also other water systems, including cooling towers and evaporative condensers operating at these facilities. As safety plans are limited to
the recreational facility and the dose response is not easily described, adequate control
measures should be defined in terms of practices that have been shown to be effective.
Important control measures include appropriate design, to minimize the available surface
area within the pool and hot tub system and associated pipework to reduce the area for
possible bacterial colonization, ensuring an adequate disinfection residual in pools and
hot tubs, proper maintenance and cleaning of equipment, and adequate ventilation.
Most of the reported legionellosis associated with recreational water use has been associated with hot tubs and natural spas (Groothuis et al., 1985; Althaus, 1986; Bornstein
et al., 1989; Mashiba et al., 1993). Natural spa waters (especially thermal water) and associated equipment create an ideal habitat (warm, nutrient-containing aerobic water) for
the selection and proliferation of Legionella. Hot tubs used for display in retail/wholesale
outlets are also potential sources of infection (McEvoy et al., 2000). Outbreaks as a result
of using swimming pools have not been reported (Marston et al., 1994), although Legionella spp. have been isolated from pool water and filter samples (Jeppesen et al., 2000;
Leoni et al., 2001). Hot tubs integrated into larger swimming pool complexes appear to
be less of a source of Legionella infection where shared water treatment facilities exist due
to dilution of hot tub water into larger volumes of water for treatment.
Increased risk of Legionella in drinking-water has been associated with systems
operating within the temperature range 25–50 °C. In hot tub facilities it is impractical to maintain a water temperature outside this range. Therefore, it is necessary to
implement a range of other management strategies, which may include:
• ensuring a constant circulation of water in the hot tub;
• programming ‘rest periods’ during hot tub operation, in order to discourage
excessive use and also to allow disinfectant levels to ‘recover’;
• frequent inspection and cleaning of all filters, including backwash filters (e.g. at
least daily and when triggered by a pressure drop);
42
layout Safe Water.indd 64
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:00
• cleaning pool surroundings, inspection of the physical conditions of the hot tub
(e.g. daily);
• replacing at least half the water in each hot tub (e.g. daily);
• completely draining hot tubs and thoroughly cleaning all surfaces and all pipework (e.g. weekly);
• maintaining and physically cleaning heating, ventilation and air-conditioning systems serving the room in which hot tubs are located (e.g. weekly to monthly);
• inspection of the sand filter (e.g. quarterly); and
• ensuring staff are appropriately qualified and competent to operate the recreational facility.
In order to control the growth of Legionella in hot tubs and natural spas, physical
cleaning of surfaces is critical, and high residual disinfectant concentrations may be
required – e.g. free chlorine, where used, must be at least 1 mg/l at all times. Features
such as water sprays, etc., in pool facilities should be periodically cleaned and flushed
with a level of disinfectant adequate to eliminate Legionella spp. (e.g. by use of a solution of at least 5 mg of hypochlorite per litre).
Bathers should be encouraged to shower before entering the water. This will remove pollutants such as perspiration, cosmetics and organic debris that can act as
a source of nutrients for bacterial growth and neutralize oxidizing biocides. Bather
density and duration spent in hot tubs should also be controlled. Public and semipublic spa facilities should have programmed rest periods during the day. High-risk
individuals (such as those with chronic lung disease) should be cautioned about the
risks of exposure to Legionella in or around pools and hot tubs.
Operators of hot tub facilities should undertake a programme of verification of
control measures, including:
• checking and adjusting residual disinfectant levels and pH (several times a day);
• inspection and maintenance of cleaning operations (daily to weekly); and
• where microbial testing for Legionella is undertaken, ensuring that Legionella
levels are <1/100 ml.
3.4.2 Pseudomonas aeruginosa
1. Risk assessment
Pseudomonas aeruginosa is an aerobic, non-spore-forming, motile, Gram-negative, straight
or slightly curved rod with dimensions 0.5–1 µm × 1.5–4 µm. It can metabolize a variety
of organic compounds and is resistant to a wide range of antibiotics and disinfectants.
P. aeruginosa is ubiquitous in water, vegetation and soil. Although shedding from
infected humans is the predominant source of P. aeruginosa in pools and hot tubs (Jacobson, 1985), the surrounding environment can be a source of contamination. The
warm, moist environment on decks, drains, benches and floors provided by pools and
similar environments is ideal for the growth of Pseudomonas, and it can grow well up
to temperatures of 41 °C (Price & Ahearn, 1988). Pseudomonas tends to accumulate
in biofilms in filters that are poorly maintained and in areas where pool hydraulics
are poor (under moveable floors, for example). It is also likely that bathers pick up
the organisms on their feet and hands and transfer them to the water. It has been
proposed that the high water temperatures and turbulence in aerated hot tubs promote perspiration and desquamation (removal of skin cells). These materials protect
CHAPTER 3.
layout Safe Water.indd 65
MICROBIAL HAZARDS
43
24.2.2006 9:57:00
organisms from exposure to disinfectants and contribute to the organic load, which,
in turn, reduces the residual disinfectant level; they also act as a source of nutrients
for the growth of P. aeruginosa (Kush & Hoadley, 1980; Ratnam et al., 1986; Price
& Ahearn, 1988).
In one study, P. aeruginosa was isolated from all nine hot tubs examined (seven of
which were commercial facilities and two domestic – Price & Ahearn, 1988). In the
majority of hot tubs, concentrations ranged from 102 to 105 per ml. Locally recommended disinfection levels (of between 3 and 5 mg/l chlorine or bromine) were not
maintained in any of the commercial hot tubs examined. In the same study, the two
domestic hot tubs developed P. aeruginosa densities of 104–106 per ml within 24–48 h
following stoppage of disinfection. In Northern Ireland, UK, Moore et al. (2002)
found P. aeruginosa in 72% of hot tubs and 38% of swimming pools examined.
In hot tubs, the primary health effect associated with the presence of P. aeruginosa is folliculitis. Otitis externa and infections of the urinary tract, respiratory tract,
wounds and cornea caused by P. aeruginosa have also been linked to hot tub use. Infection of hair follicles in the skin with P. aeruginosa produces a pustular rash, which
may appear under surfaces covered with swimwear or may be more intense in these
areas (Ratnam et al., 1986). The rash appears 48 h (range 8 h to 5 days) after exposure
and usually resolves spontaneously within 5 days. It has been suggested that warm
water supersaturates the epidermis, dilates dermal pores and facilitates their invasion
by P. aeruginosa (Ratnam et al., 1986). There are some indications that extracellular
enzymes produced by P. aeruginosa may damage skin and contribute to the bacteria’s
colonization (Highsmith et al., 1985). Other symptoms, such as headache, muscular
aches, burning eyes and fever, have been reported. Some of these secondary symptoms resemble humidifier fever (Weissman & Schuyler, 1991) and therefore could
be caused by the inhalation of P. aeruginosa endotoxins. Investigations have indicated
that duration or frequency of exposure, bather loads, bather age and using the facility
later in the day can be significant risk factors for folliculitis (Hudson et al., 1985; Ratnam et al., 1986; CDC, 2000). The sex of bathers does not appear to be a significant
risk factor, but Hudson et al. (1985) suggest that women wearing one-piece bathing
suits may be more susceptible to infection, presumably because one-piece suits trap
more P. aeruginosa-contaminated water next to the skin. It has been suggested that the
infective dose for healthy individuals is greater than 1000 organisms per ml (Price &
Ahearn, 1988; Dadswell, 1997).
In swimming pools, the primary health effect associated with P. aeruginosa is otitis
externa or swimmer’s ear, although folliculitis has also been reported (Ratnam et al.,
1986). Otitis externa is characterized by inflammation, swelling, redness and pain in
the external auditory canal. Risk factors reported to increase the occurrence of otitis
externa related to water exposure include amount of time spent in the water prior
to the infection, less than 19 years of age and a history of previous ear infections
(Seyfried & Cook, 1984; van Asperen et al., 1995). Repeated exposure to water is
thought to remove the protective wax coating of the external ear canal, predisposing
it to infection.
An indoor swimming pool with a system of water sprays has been implicated as
the source of two sequential outbreaks of granulomatous pneumonitis among lifeguards (Rose et al., 1998). Inadequate chlorination led to the colonization of the
spray circuits and pumps with Gram-negative bacteria, predominantly P. aeruginosa.
44
layout Safe Water.indd 66
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:00
The bacteria and associated endotoxins were aerosolized and respired by the lifeguards
when the sprays were activated. When the water spray circuits were replaced and supplied with an ozonation and chlorination system, there were no further occurrences
of disease among personnel.
An outbreak of pseudomonas hot-foot syndrome, erythematous plantar nodules,
has been reported as a result of exposure to a community wading pool. The floor of
the pool was coated in abrasive grit, and the water contained high concentrations of P.
aeruginosa (Fiorillo et al., 2001). Another outbreak occurred in Germany due to high
concentrations of P. aeruginosa on the stairs to a water slide and resulted in some of
the children being admitted to hospital (A. Wiedenmann, pers. comm.).
The true incidence of illnesses associated with P. aeruginosa in pools and similar
environments is difficult to determine. Since the symptoms are primarily mild and
self-limiting, most patients do not seek medical attention. In the USA, Yoder et al.
(2004) reported 20 outbreaks of dermatitis between 2000 and 2001 associated with
pools and hot tubs. In eight of these outbreaks P. aeruginosa was identified from water
or filter samples; in the other 12 outbreaks Pseudomonas was suspected to be the cause.
It was noted that contributing factors to these outbreaks included inadequate pool
and hot tub maintenance and exceeding the bather load limit.
2. Risk management
Maintaining adequate residual disinfectant levels and routine cleaning are the key elements to controlling P. aeruginosa in swimming pools and similar recreational environments (see Chapter 5). While maintaining residual disinfectant levels in pools is relatively easy, the design and operation of some hot tubs make it difficult to achieve adequate
disinfectant levels in these facilities. Under normal operating conditions, disinfectants
can quickly dissipate (Highsmith et al., 1985; Price & Ahearn, 1988). In all facilities,
frequent monitoring and adjustment of pH and disinfectant levels are essential. Most
hot tubs use either chlorine- or bromine-based disinfectants. Shaw (1984) showed that
chlorination was superior to bromine in controlling P. aeruginosa. He reported that during an outbreak investigation, P. aeruginosa could be isolated from water despite having
a total bromine level of 5 mg/l and a pH of 7.5. Even in hot tubs with heterotrophic
plate counts of <1 cfu/ml, P. aeruginosa was isolated from 5% of bromine-disinfected
pools compared with only 0.8% of chlorine-disinfected pools (Shaw, 1984).
Routine, thorough cleaning of surrounding surfaces will help to reduce infections
with P. aeruginosa. In addition, swimming pool, hot tub and natural spa operators
should strongly encourage users to shower before entering the water and, where possible, control the number of bathers and their duration of hot tub exposure (Public
Health Laboratory Service Spa Pools Working Group, 1994).
3.4.3 Mycobacterium spp.
1. Risk assessment
Mycobacterium spp. are rod-shaped bacteria that are 0.2–0.6 µm × 1.0–10 µm in size
and have cell walls with a high lipid content. This feature means that they retain dyes
in staining procedures that employ an acid wash; hence, they are often referred to as
acid-fast bacteria. Atypical mycobacteria (i.e. other than strictly pathogenic species,
such as M. tuberculosis) are ubiquitous in the aqueous environment and proliferate in
and around swimming pools and similar environments (Leoni et al., 1999).
CHAPTER 3.
layout Safe Water.indd 67
MICROBIAL HAZARDS
45
24.2.2006 9:57:01
In pool environments, M. marinum is responsible for skin and soft tissue infections
in normally healthy people. Infections frequently occur on abraded elbows and knees
and result in localized lesions, often referred to as swimming pool granuloma. The
organism is probably picked up from the pool edge by bathers as they climb in and
out of the pool (Collins et al., 1984).
Respiratory illnesses associated with hot tub use in normally healthy individuals
have been linked to other atypical mycobacteria (Embil et al., 1997; Kahana et al.,
1997; Grimes et al., 2001; Khoor et al., 2001; Mangione et al., 2001; Cappelluti
et al., 2003; Lumb et al., 2004). For example, M. avium in hot tub water has been
linked to hypersensitivity pneumonitis and possibly pneumonia (Embil et al., 1997).
Symptoms were flu-like and included cough, fever, chills, malaise and headaches. The
illness followed the inhalation of heavily contaminated aerosols generated by the hot
tub. The reported cases relate to domestic hot tubs, many of which were located outdoors. In most instances the frequency of hot tub use was high, as was the duration
of exposure (an extreme example being use for 1–2 h each day), and maintenance of
disinfection and cleaning were not ideal. It is likely that detected cases are only a small
fraction of the total number of cases. Amoebae may also play a role in the transmission of Mycobacterium spp. (Cirillo et al., 1997).
2. Risk management
Mycobacteria are more resistant to disinfection than most bacteria due to the high lipid content of their cell wall (Engelbrecht et al., 1977). Therefore, thorough cleaning
of surfaces and materials around pools and hot tubs where the organism may persist
is necessary, supplemented by the maintenance of disinfection at appropriate levels.
In addition, occasional shock dosing of chlorine (see Chapter 5) may be required to
eradicate mycobacteria accumulated in biofilms within pool or hot tub components
(Aubuchon et al., 1986). In natural spas where the use of disinfectants is undesirable
or where it is difficult to maintain adequate disinfectant levels, superheating the water
to 70 °C on a daily basis during periods of non-use may help to control M. marinum
(Embil et al., 1997). Immunocompromised individuals should be cautioned about
the risks of exposure to atypical mycobacteria in and around pools and hot tubs.
3.4.4 Staphylococcus aureus
1. Risk assessment
The genus Staphylococcus comprises non-motile, non-spore-forming and non-encapsulated Gram-positive cocci (0.5–1.5 µm in diameter) that ferment glucose and grow
aerobically and anaerobically. They are usually catalase positive and occur singly and
in pairs, tetrads, short chains and irregular grape-like clusters. In humans, there are
three clinically important species – Staphylococcus aureus, S. epidermidis and S. saprophyticus. S. aureus is the only coagulase-positive species and is clinically the most
important (Duerden et al., 1990).
Humans are the only known reservoir of S. aureus, and it is found on the anterior
nasal mucosa and skin as well as in the faeces of a substantial portion of healthy individuals. Robinton & Mood (1966) found that S. aureus was shed by bathers under all
conditions of swimming, and the bacteria can be found in surface films in pool water.
Coagulase-positive Staphylococcus strains of normal human flora have been found in
chlorinated swimming pools (Rocheleau et al., 1986).
46
layout Safe Water.indd 68
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:01
The presence of S. aureus in swimming pools is believed to have resulted in skin
rashes, wound infections, urinary tract infections, eye infections, otitis externa, impetigo and other infections (Calvert & Storey, 1988; Rivera & Adera, 1991). Infections
of S. aureus acquired from recreational waters may not become apparent until 48 h
after contact. De Araujo et al. (1990) have suggested that recreational waters with a
high density of bathers present a risk of staphylococcal infection that is comparable to
the risk of gastrointestinal illness involved in bathing in water considered unsafe because of faecal pollution. According to Favero et al. (1964) and Crone & Tee (1974),
50% or more of the total staphylococci isolated from swimming pool water samples
are S. aureus. In Italy, however, in a study on chlorinated pools where the free chlorine
level varied between 0.8 and 1.2 mg/l, S. aureus was not recovered from water samples
(Bonadonna et al., 2004).
2. Risk management
Adequate inactivation of potentially pathogenic S. aureus in swimming pools can be
attained by maintaining free chlorine levels greater than 1 mg/l (Keirn & Putnam,
1968; Rivera & Adera, 1991) or equivalent disinfection efficiency. There is evidence
that showering before pool entry can reduce the shedding of staphylococci from the
skin into the pool (Robinton & Mood, 1966). Continuous circulation of surface water through the treatment process helps to control the build-up of S. aureus. Pool contamination can also be reduced if the floors surrounding the pool and in the changing
areas are kept at a high standard of cleanliness. Although it is not recommended that
water samples be routinely monitored for S. aureus, where samples are taken, levels
should be less than 100/100 ml.
3.4.5 Leptospira interrogans sensu lato
1. Risk assessment
Leptospires are motile spirochaete (helically coiled) bacteria. Traditionally, the genus
Leptospira consists of two species, the pathogenic L. interrogans sensu lato and the
saprophytic L. biflexa sensu lato. Serological tests within each species revealed many
antigenic variations, and, on this basis, leptospires are classified as serovars. In addition, a classification system based on DNA relatedness is used (Brenner et al., 1999).
The current species determination is based on this principle. The serological and
genetic taxonomies are two different systems with only little correlation (Brenner et
al., 1999). Free-living strains (L. biflexa sensu lato) are ubiquitous in the environment
(Faine et al., 1999); the pathogenic strains (L. interrogans sensu lato), however, live in
the kidneys of animal hosts.
Pathogenic leptospires live in the proximal renal tubules of the kidneys of carrier
animals (including rats, cows and pigs) and are excreted in the urine, which can then
contaminate surface waters. Humans and animals (humans are always incidental hosts)
become infected either directly through contact with infected urine or indirectly via contact with contaminated water. Leptospires gain entry to the body through cuts and abrasions of the skin and through the mucosal surfaces of the mouth, nose and conjunctiva.
Diseases caused by Leptospira interrogans sensu lato have been given a variety of
names, including swineherd’s disease, Stuttgart disease and Weil’s syndrome, but collectively all of these infections are termed leptospirosis. The clinical manifestations
of leptospirosis vary considerably in form and intensity, ranging from a mild flu-like
CHAPTER 3.
layout Safe Water.indd 69
MICROBIAL HAZARDS
47
24.2.2006 9:57:02
illness to a severe and potentially fatal form of the disease, characterized by liver and
kidney failure and haemorrhages (Weil’s syndrome). Severity is related to the infecting
serovar as well as host characteristics, such as age and underlying health and nutritional status. Specific serovars are often associated with certain hosts.
Compared with many other pathogens, leptospires have a comparatively low resistance to adverse chemical and physical conditions, including disinfectants. They are
seldom found in water of below pH 6.8, and they cannot tolerate drying or exposure
to direct sunlight (Noguchi, 1918; Alston & Broom, 1958; Weyant et al., 1999).
The majority of reported outbreaks of waterborne leptospirosis have involved fresh
recreational waters, but two outbreaks have been associated with non-chlorinated
swimming pools (Cockburn et al., 1954; de Lima et al., 1990). Domestic or wild
animals with access to the implicated waters were the probable sources of Leptospira.
2. Risk management
The risk of leptospirosis can be reduced by preventing direct animal access to swimming pools and maintaining adequate disinfectant concentrations. Informing users
about the hazards of swimming in water that is accessible to domestic and wild animals may also help to prevent infections. Outbreaks are not common; thus, it appears
that the risk of leptospirosis associated with swimming pools and hot tubs is low.
Normal disinfection of pools is sufficient to inactivate Leptospira spp.
3.5 Non-faecally-derived viruses
Infections associated with non-faecally-derived viruses found in swimming pools and
similar environments are summarized in Table 3.7.
Table 3.7. Non-faecally-derived viruses found in swimming pools and similar environments and
their associated infections
Organism
Infection
Source
Adenoviruses
Pharyngo-conjunctivitis
(swimming pool conjunctivitis)
Other infected bathers
Molluscipoxvirus
Molluscum contagiosum
Bather shedding on benches,
pool or hot tub decks,
swimming aids
Papillomavirus
Plantar wart
Bather shedding on pool and
hot tub decks and floors in
showers and changing rooms
a
a
Covered in Section 3.1.2
3.5.1 Molluscipoxvirus
1. Risk assessment
Molluscipoxvirus is a double-stranded DNA virus in the Poxviridae family. Virions
are brick-shaped, about 320 nm × 250 nm × 200 nm. The virus causes molluscum
contagiosum, an innocuous cutaneous disease limited to humans. It is spread by direct
person-to-person contact or indirectly through physical contact with contaminated
48
layout Safe Water.indd 70
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:02
surfaces. The infection appears as small, round, firm papules or lesions, which grow
to about 3–5 mm in diameter. The incubation period is 2–6 weeks or longer. Individual lesions persist for 2–4 months, and cases resolve spontaneously in 0.5–2 years.
Swimming pool-related cases occur more frequently in children than in adults. The
total number of annual cases is unknown. Since the infection is relatively innocuous,
the reported number of cases is likely to be much less than the total number. Lesions
are most often found on the arms, back of the legs and back, suggesting transmission through physical contact with the edge of the pool, benches around the pool,
swimming aids carried into the pool or shared towels (Castilla et al., 1995). Indirect
transmission via water in swimming pools is not likely. Although cases associated with
hot tubs have not been reported, they should not be ruled out as a route of exposure.
2. Risk management
The only source of molluscipoxvirus in swimming pool and similar facilities is infected bathers (Oren & Wende, 1991). Hence, the most important means of controlling
the spread of the infection is to educate the public about the disease, the importance
of limiting contact between infected and non-infected people and medical treatment.
Thorough frequent cleaning of surfaces in facilities that are prone to contamination
can reduce the spread of the disease.
3.5.2 Papillomavirus
1. Risk assessment
Papillomavirus is a double-stranded DNA virus in the family Papovaviridae. The virions
are spherical and approximately 55 nm in diameter. The virus causes benign cutaneous
tumours in humans. An infection that occurs on the sole (or plantar surface) of the
foot is referred to as a verruca plantaris or plantar wart. Papillomaviruses are extremely
resistant to desiccation and thus can remain infectious for many years. The incubation
period of the virus remains unknown, but it is estimated to be 1–20 weeks. The infection is extremely common among children and young adults between the ages of 12
and 16 who frequent public pools and hot tubs. It is less common among adults, suggesting that they acquire immunity to the infection. At facilities such as public swimming pools, plantar warts are usually acquired via direct physical contact with shower
and changing room floors contaminated with infected skin fragments (Conklin, 1990;
Johnson, 1995). Papillomavirus is not transmitted via pool or hot tub waters.
2. Risk management
The primary source of papillomavirus in swimming pool facilities is infected bathers.
Hence, the most important means of controlling the spread of the virus is to educate
the public about the disease, the importance of limiting contact between infected and
non-infected people and medical treatment. The use of pre-swim showering, wearing
of sandals in showers and changing rooms and regular cleaning of surfaces in swimming
pool facilities that are prone to contamination can reduce the spread of the virus.
3.6 Non-faecally-derived protozoa
Table 3.8 summarizes the non-faecally-derived protozoa found in or associated with
swimming pools and similar environments and their associated infections.
CHAPTER 3.
layout Safe Water.indd 71
MICROBIAL HAZARDS
49
24.2.2006 9:57:03
Table 3.8. Non-faecally-derived protozoa found in swimming pools and similar environments
and their associated infections
Organism
Infection
Source
Naegleria fowleri
Primary amoebic
meningoencephalitis (PAM)
Pools, hot tubs and natural spas
including water and components
Acanthamoeba
spp.
Acanthamoeba keratitis
Aerosols from HVAC systems
Granulomatous amoebic encephalitis (GAE)
Plasmodium spp.
Malaria
Seasonally used pools may provide
a breeding habitat for mosquitoes
carrying Plasmodium
HVAC – heating, ventilation and air conditioning
3.6.1 Naegleria fowleri
1. Risk assessment
Naegleria fowleri is a free-living amoeba (i.e. it does not require the infection of a
host organism to complete its life cycle) present in fresh water and soil. The life cycle
includes an environmentally resistant encysted form. Cysts are spherical, 8–12 µm in
diameter, with smooth, single-layered walls containing one or two mucus-plugged
pores through which the trophozoites (infectious stages) emerge. N. fowleri is thermophilic, preferring warm water and reproducing successfully at temperatures up to
46 °C.
N. fowleri causes primary amoebic meningoencephalitis (PAM). Infection is usually acquired by exposure to water in ponds, natural spas and artificial lakes (Martinez
& Visvesvara, 1997; Szenasi et al., 1998). Victims are usually healthy children and
young adults who have had contact with water about 7–10 days before the onset of
symptoms (Visvesvara, 1999). Infection occurs when water containing the organisms
is forcefully inhaled or splashed onto the olfactory epithelium, usually from diving,
jumping or underwater swimming. The amoebae in the water then make their way
into the brain and central nervous system. Symptoms of the infection include severe
headache, high fever, stiff neck, nausea, vomiting, seizures and hallucinations. The
infection is not contagious. For those infected, death occurs usually 3–10 days after
onset of symptoms. Respiratory symptoms occur in some patients and may be the
result of hypersensitivity or allergic reactions or may represent a subclinical infection
(Martinez & Visvesvara, 1997).
Although PAM is an extremely rare disease, cases have been associated with pools
and natural spas. In Usti, Czech Republic, 16 cases of PAM were associated with a
public swimming pool (Cerva & Novak, 1968). The source of the contamination was
traced to a cavity behind a false wall used to shorten the pool length. The pool took
water from a local river, which was the likely source of the organism. One confirmed
case of PAM occurred in Bath Spa, in the UK, in 1978. The victim was a young girl
who swam in a public swimming pool fed with water from the historic thermal springs
that rise naturally in the city (Cain et al., 1981). Subsequent analysis confirmed the
thermal springs to be the source of the infection (Kilvington et al., 1991). N. fowleri
has also been isolated from air-conditioning units (Martinez, 1993).
50
layout Safe Water.indd 72
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:03
2. Risk management
Risk of infection can be reduced by minimizing the occurrence of the causative agent
through appropriate choice of source water, proper cleaning, maintenance, coagulation–
filtration and disinfection.
3.6.2 Acanthamoeba spp.
1. Risk assessment
Several species of free-living Acanthamoeba are human pathogens (A. castellanii, A.
culbertsoni, A. polyphaga). They can be found in all aquatic environments, including
disinfected swimming pools. Under adverse conditions, they form a dormant encysted stage. Cysts measure 15–28 µm, depending on the species. Acanthamoeba cysts
are highly resistant to extremes of temperature, disinfection and desiccation. The cysts
will retain viability from –20 °C to 56 °C. When favourable conditions occur, such as
a ready supply of bacteria and a suitable temperature, the cysts hatch (excyst) and the
trophozoites emerge to feed and replicate. All pathogenic species will grow at 36–37 °C,
with an optimum of about 30 °C. Although Acanthamoeba is common in most environments, human contact with the organism rarely leads to infection.
Human pathogenic species of Acanthamoeba cause two clinically distinct diseases:
granulomatous amoebic encephalitis (GAE) and inflammation of the cornea (keratitis) (Ma et al., 1990; Martinez, 1991; Kilvington & White, 1994).
GAE is a chronic disease of the immunosuppressed; GAE is either subacute or
chronic but is invariably fatal. Symptoms include fever, headaches, seizures, meningitis
and visual abnormalities. GAE is extremely rare, with only 60 cases reported worldwide. The route of infection in GAE is unclear, although invasion of the brain may
result from the blood following a primary infection elsewhere in the body, possibly the
skin or lungs (Martinez, 1985, 1991). The precise source of such infections is unknown
because of the almost ubiquitous presence of Acanthamoeba in the environment.
Acanthamoeba keratitis affects previously healthy people and is a severe and potentially blinding infection of the cornea (Ma et al., 1990; Kilvington & White,
1994). In the untreated state, acanthamoeba keratitis can lead to permanent blindness. Although only one eye is usually affected, cases of bilateral infection have been
reported. The disease is characterized by intense pain and ring-shaped infiltrates in
the corneal stroma. Contact lens wearers are most at risk from the infection and account for approximately 90% of reported cases (Kilvington & White, 1994). Poor
contact lens hygiene practices (notably ignoring recommended cleaning and disinfection procedures and rinsing or storing of lenses in tap water or non-sterile saline
solutions) are recognized risk factors, although the wearing of contact lenses while
swimming or participating in other water sports may also be a risk factor. In noncontact lens related keratitis, infection arises from trauma to the eye and contamination with environmental matter such as soil and water (Sharma et al., 1990). Samples
et al. (1984) report a case of keratitis that may have been acquired from domestic
hot tub use.
2. Risk management
Although Acanthamoeba cysts are resistant to chlorine- and bromine-based disinfectants, they can be removed by filtration. Thus, it is unlikely that properly operated
CHAPTER 3.
layout Safe Water.indd 73
MICROBIAL HAZARDS
51
24.2.2006 9:57:03
swimming pools and similar environments would contain sufficient numbers of cysts
to cause infection in normally healthy individuals. Immunosuppressed individuals
who use swimming pools, natural spas or hot tubs should be aware of the increased
risk of GAE. A number of precautionary measures are available to contact lens wearers, including removal before entering the water, wearing goggles, post-swim contact
lens wash using appropriate lens fluid and use of daily disposable lenses.
3.6.3 Plasmodium spp.
1. Risk assessment
Swimming pools are associated not with Plasmodium spp. but with anopheline mosquito larvae, the insect vectors of Plasmodium. Mbogo et al. (submitted) found that
over 70% of swimming pools sampled in urban Malindi in Kenya were positive for
mosquito larvae. The problem relates to the seasonal use of the pools. Before people
leave their summer houses, it is common to drain the pool; however, rainwater accumulated during the rainy season provides a suitable habitat for mosquito breeding,
with the attendant risks of malaria as a result.
2. Risk management
During the rains, when the pools fill with water, they should be drained every
5–7 days to avoid mosquito larvae developing into adults. The swimming pools may
also be treated with appropriate larvicides when not in use for long periods.
3.7 Non-faecally-derived fungi
Infections associated with fungi found in swimming pools and similar environments
are summarized in Table 3.9.
Table 3.9. Fungi found in swimming pools and similar environments and their associated infections
Organism
Infection
Source
Trichophyton spp.
Epidermophyton floccosum
Athlete’s foot (tinea
pedis)
Bather shedding on floors in changing
rooms, showers and pool or hot tub decks
3.7.1 Trichophyton spp. and Epidermophyton floccosum
1. Risk assessment
Epidermophyton floccosum and various species of fungi in the genus Trichophyton cause
superficial fungal infections of the hair, fingernails or skin. Infection of the skin of
the foot (usually between the toes) is described as tinea pedis or, more commonly,
as ‘athlete’s foot’ (Aho & Hirn, 1981). Symptoms include maceration, cracking and
scaling of the skin, with intense itching. Tinea pedis may be transmitted by direct
person-to-person contact; in swimming pools, however, it may be transmitted by
physical contact with surfaces, such as floors in public showers, changing rooms, etc.,
contaminated with infected skin fragments. In Japan, a study comparing students attending a regular swimming class with those who did not found a significantly greater
level of infection in the swimmers (odds ratio of 8.5), and Trichophyton spp. were
52
layout Safe Water.indd 74
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:04
isolated from the floor of a hot tub and the floor of one of the changing rooms (Kamihama et al., 1997). The fungus colonizes the stratum corneum when environmental
conditions, particularly humidity, are optimal. From in vitro experiments, it has been
calculated that it takes approximately 3–4 h for the fungus to initiate infection. The
infection is common among lifeguards and competitive swimmers, but relatively benign; thus, the true number of cases is unknown.
2. Risk management
The sole source of these fungi in swimming pool and similar facilities is infected bathers.
Hence, the most important means of controlling the spread of the fungus is to educate
the public about the disease, the importance of limiting contact between infected and
non-infected bathers and medical treatment. The use of pre-swim showers, wearing of
sandals in showers and changing rooms and frequent cleaning of surfaces in swimming
pool facilities that are prone to contamination can reduce the spread of the fungi (AlDoory & Ramsey, 1987). People with severe athlete’s foot or similar dermal infections
should not frequent public swimming pools, natural spas or hot tubs. Routine disinfection appears to control the spread of these fungi in swimming pools and similar environments (Public Health Laboratory Service Spa Pools Working Group, 1994).
3.8 References
Aho R, Hirn H (1981) A survey of fungi and some indicator bacteria in chlorinated water of indoor public
swimming pools. Zentralblatt für Bakteriologie, Mikrobiologie und Hygiene B, 173: 242–249.
Al-Doory Y, Ramsey S (1987) Cutaneous mycotic diseases. In: Moulds and health: Who is at risk? Springfield, IL, Charles C. Thomas, pp. 61–68, 206–208.
Alston JM, Broom JC (1958) Leptospirosis in man and animals. Edinburgh, Livingstone Ltd.
Althaus H (1986) Legionellas in swimming pools. A.B. Archiv des Badewesens, 38: 242–245.
Atlas RM (1999) Legionella: from environmental habitats to disease pathology, detection and control.
Environmental Microbiology, 1(4): 283–293.
Aubuchon C, Hill JJ, Graham DR (1986) Atypical mycobacterial infection of soft tissue associated with
use of a hot tub. Journal of Bone and Joint Surgery, 68-A(5): 766–768.
Bell A, Guasparini R, Meeds D, Mathias RG, Farley JD (1993) A swimming pool associated outbreak of
cryptosporidiosis in British Columbia. Canadian Journal of Public Health, 84: 334–337.
Blostein J (1991) Shigellosis from swimming in a park in Michigan. Public Health Reports, 106: 317–322.
Bonadonna L, Briancesco R, Magini V, Orsini M, Romano-Spica V (2004) [A preliminary investigation on
the occurrence of protozoa in swimming pools in Italy.] Annali di Igiene Medicina Preventiva e di Comunità,
16(6): 709–720 (in Italian).
Bornstein N, Marmet D, Surgot M, Nowicki M, Arslan A, Esteve J, Fleurette J (1989) Exposure to Legionellaceae at a hot spring spa: a prospective clinical and serological study. Epidemiology and Infection, 102: 31–36.
Brenner DJ, Kaufmann AF, Sulzer KR, Steigerwalt AG, Rogers FC, Weyant RS (1999) Further determination of DNA relatedness between serogroups and serovars in the family Leptospiraceae with a proposal for
Leptospira alexanderi sp. Nov and four new Leptospira genomospecies. International Journal of Systematic
Bacteriology, 49: 833–858.
Brewster DH, Brown MI, Robertson D, Houghton GL, Bimson J, Sharp JCM (1994) An outbreak of Escherichia coli O157 associated with a children’s paddling pool. Epidemiology and Infection, 112: 441–447.
Cain ARR, Wiley PF, Brownwell B, Warhurst DC (1981) Primary amoebic meningoencephalitis. Archives
of Diseases in Childhood, 56: 140–143.
CHAPTER 3.
layout Safe Water.indd 75
MICROBIAL HAZARDS
53
24.2.2006 9:57:04
Caldwell GG, Lindsey NJ, Wulff H, Donnelly DD, Bohl FN (1974) Epidemic with adenovirus type 7
acute conjunctivitis in swimmers. American Journal of Epidemiology, 99: 230–234.
Calvert J, Storey A (1988) Microorganisms in swimming pools – are you looking for the right one? Journal
of the Institution of Environmental Health Officers, 96(7): 12.
Cappelluti E, Fraire AE, Schaefer OP (2003) A case of ‘hot tub lung’ due to Mycobacterium avium complex
in an immunocompetent host. Archives of Internal Medicine, 163: 845–848.
Carpenter C, Fayer R, Trout J, Beach MJ (1999) Chlorine disinfection of recreational water for Cryptosporidium parvum. Emerging Infectious Diseases, 5(4): 579–584.
Casemore DP (1990) Epidemiological aspects of human cryptosporidiosis. Epidemiology and Infection,
104: 1–28.
Castilla MT, Sanzo JM, Fuentes S (1995) Molluscum contagiosum in children and its relationship to attendance at swimming-pools: an epidemiological study. Dermatology, 191(2): 165.
CDC (1990) Swimming-associated cryptosporidiosis – Los Angeles County. Morbidity and Mortality
Weekly Report, 39: 343–345.
CDC (1994) Cryptosporidium infections associated with swimming pools – Dane County, Wisconsin.
Morbidity and Mortality Weekly Report, 43: 561–563.
CDC (1996) Lake-associated outbreak of Escherichia coli O157-H7 – Illinois. Morbidity and Mortality
Weekly Report, 45: 437–439.
CDC (2000) Pseudomonas dermatitis/folliculitis associated with pools and hot tubs – Colorado and Maine,
1999–2000. Morbidity and Mortality Weekly Report, 49: 1087–1091.
CDC (2001a) Prevalence of parasites in fecal material from chlorinated swimming pools – United States,
1999. Morbidity and Mortality Weekly Report, 50: 410–412.
CDC (2001b) Shigellosis outbreak associated with an unchlorinated fill-and-drain wading pool – Iowa,
2001. Morbidity and Mortality Weekly Report, 50(37): 797–800.
CDC (2001c) Protracted outbreaks of cryptosporidiosis associated with swimming pool use – Ohio and
Nebraska, 2000. Morbidity and Mortality Weekly Report, 50(20): 406–410.
CDC (2004) An outbreak of norovirus gastroenteritis at a swimming club – Vermont, 2004. Morbidity and
Mortality Weekly Report, 53: 793–795.
CDSC (1995) Surveillance of waterborne diseases. Communicable Disease Report Weekly, 5: 129.
CDSC (1997) Surveillance of waterborne disease and water quality: January to June 1997. Communicable
Disease Report Weekly, 7: 317–319.
CDSC (1998) Surveillance of waterborne disease and water quality: January to June 1998. Communicable
Disease Report Weekly, 8: 305–306.
CDSC (1999) Surveillance of waterborne disease and water quality: January to June 1999, and summary
of 1998. Communicable Disease Report Weekly, 9: 305–308.
CDSC (2000) Surveillance of waterborne disease and water quality: July to December 1999. Communicable Disease Report Weekly, 10: 65–68.
Cerva L, Novak K (1968) Amoebic meningoencephalitis: sixteen fatalities. Science, 160: 92.
Cirillo JD, Falkow S, Tompkins LS, Bermudez LE (1997) Interaction of Mycobacterium avium with environmental amoebae enhances virulence. Infection and Immunity, 65(9): 3759–3767.
Cockburn TA, Vavra JD, Spencer SS, Dann JR, Peterson LJ, Reinhard KR (1954) Human leptospirosis
associated with a swimming pool diagnosed after eleven years. American Journal of Hygiene, 60: 1–7.
Collins CH, Grange JM, Yates MD (1984) A review. Mycobacterium in water. Journal of Applied Bacteriology, 57(2): 193–211.
Conklin RJ (1990) Common cutaneous disorders in athletes. Sports Medicine, 9: 100–119.
54
layout Safe Water.indd 76
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:04
Coulepis AG, Locarnini SA, Lehmann NI, Gust ID (1980) Detection of hepatitis A virus in the feces of
patients with naturally acquired infections. Journal of Infectious Diseases, 141(2): 151–156.
Cransberg K, van den Kerkhof JH, Banffer JR, Stijnen C, Wernors K, van de Kar NC, Nauta J, Wolff
ED (1996) Four cases of hemolytic uremic syndrome – source contaminated swimming water? Clinical
Nephrology, 46: 45–49.
Crone PB, Tee GH (1974) Staphylococci in swimming pool water. Journal of Hygiene (London), 73(2): 213–220.
D’Angelo LJ, Hierholzer JC, Keenlyside RA, Anderson LJ, Martone WJ (1979) Pharyngo-conjunctival fever
caused by adenovirus type 4: Recovery of virus from pool water. Journal of Infectious Diseases, 140: 42–47.
Dadswell J (1997) Poor swimming pool management: how real is the health risk? Environmental Health,
105(3): 69–73.
de Araujo MA, Guimaraes VF, Mendonca-Hagler LCS, Hagler AN (1990) Staphylococcus aureus and faecal
streptococci in fresh and marine waters of Rio de Janeiro, Brazil. Revista de Microbiologia, 21(2): 141–147.
de Lima SC, Sakata EE, Santo CE, Yasuda PH, Stiliano SV, Ribeiro FA (1990) Outbreak of human leptospirosis by recreational activity in the municipality of Sao Jose dos Campos, Sao Paulo. Seroepidemiological
study. Revista do Instituto de Medicina Tropical de Sao Paulo, 32(6): 474–479.
Donlan R (2002) Biofilms: microbial life on surfaces. Emerging Infectious Diseases, 8(9): 881–890.
Duerden BI, Reid TMS, Jewsbury JM, Turk DC (1990) Microbial and parasitic infection. London, Edward
Arnold, pp. 74–76.
DuPont HL (1988) Shigella. Infectious Disease Clinics of North America, 2(3): 599–605.
DuPont HL, Chappell CL, Sterling CR, Okhuysen PC, Rose JB, Jakubowski W (1995) The infectivity of
Cryptosporidium parvum in healthy volunteers. New England Journal of Medicine, 332(13): 855–859.
Embil J, Warren P, Yakrus M, Corne S, Forrest D, Hershfield E (1997) Pulmonary illness associated with
exposure to Mycobacterium-avium complex in hot tub water. Chest, 111(3): 534–536.
Engelbrecht RS, Severnin BF, Massarik MT, Faroo S, Lee SH, Haas CN, Lalchandani A (1977) New microbial indicators of disinfection efficiency. Washington, DC, United States Environmental Protection Agency
(Report No. EPA 600/2-77-052).
Faine S, Adler B, Bolin C, Perolat P (1999) Leptospira and leptospirosis, 2nd ed. Melbourne, MediSci, 272 pp.
Favero MS, Drake CH, Randall GB (1964) Use of staphylococci as indicators of swimming pool pollution.
Public Health Reports, 79: 61–70.
Feachem RG, Bradley DJ, Garelick H, Mara DD (1983) Sanitation and disease: Health aspects of excreta and
wastewater management. New York, NY, John Wiley and Sons.
Fiorillo L, Zucker M, Sawyer D, Lin AN (2001) The pseudomonas hot-foot syndrome. New England
Journal of Medicine, 345(5): 335–338.
Fournier S, Dubrou S, Liguory O, Gaussin F, Santillana-Hayat M, Sarfati C, Molina JM, Derouin F
(2002) Detection of microsporidia, cryptosporidia and giardia in swimming pools: a one-year prospective
study. FEMS Immunology and Medical Microbiology, 33: 209–213.
Fox JP, Brandt CD, Wassermann FE, Hall CE, Spigland CE, Kogan A, Elveback LR (1969) The Virus
Watch Program: A continuing surveillance of viral infections in metropolitan New York families. VI. Observations of adenovirus infections; virus excretion patterns, antibody response, efficiency of surveillance
patterns of infection and relation to illness. American Journal of Epidemiology, 89: 25–50.
Foy HM, Cooney MK, Hatlen JB (1968) Adenovirus type 3 epidemic associated with intermittent chlorination of a swimming pool. Archives of Environmental Health, 17: 795–802.
Galmes A, Nicolau A, Arbona G, Gomis E, Guma M, Smith-Palmer A, Hernandez-Pezzi G, Soler P (2003) Cryptosporidiosis outbreak in British tourists who stayed at a hotel in Majorca, Spain. Eurosurveillance Weekly, 7(33).
Gray SF, Gunnell DJ, Peters TJ (1994) Risk factors for giardiasis: a case–control study in Avon and Somerset. Epidemiology and Infection, 113: 95–102.
CHAPTER 3.
layout Safe Water.indd 77
MICROBIAL HAZARDS
55
24.2.2006 9:57:04
Greensmith CT, Stanwick RS, Elliot BE, Fast MV (1988) Giardiasis associated with the use of a water slide.
Pediatric Infectious Diseases Journal, 7: 91–94.
Gregory R (2002) Bench-marking pool water treatment for coping with Cryptosporidium. Journal of Environmental Health Research, 1: 11–18.
Grimes MM, Cole TJ, Fowler III AA (2001) Obstructive granulomatous bronchiolitis due to Mycobacterium avium complex in an immunocompetent man. Respiration, 68: 411–415.
Groothuis DG, Havelaar AH, Veenendaal HR (1985) A note on legionellas in whirlpools. Journal of Applied Bacteriology, 58(5): 479–481.
Harley D, Harrower B, Lyon M, Dick A (2001) A primary school outbreak of pharyngoconjunctival fever
caused by adenovirus type 3. Communicable Diseases Intelligence, 25(1): 9–12.
Harter L, Frost F, Grunenfelder G, Perkins-Jones K, Libby J (1984) Giardiasis in an infant and toddler
swim class. American Journal of Public Health, 74: 155–156.
Highsmith AK, Le PN, Khabbaz RF, Munn VP (1985) Characteristics of Pseudomonas aeruginosa isolated
from whirlpools and bathers. Infection Control, 6(10): 407–412.
Hildebrand JM, Maguire HC, Halliman RE, Kangesu E (1996) An outbreak of Escherichia coli O157
infection linked to paddling pools. Communicable Disease Report Review, 6: R33–R36.
Hudson PJ, Vogt RL, Jillson DA, Kappel SJ, Highsmith AK (1985) Duration of whirlpool-spa use as a risk
factor for Pseudomonas dermatitis. American Journal of Epidemiology, 122: 915–917.
Hunt DA, Sebugwawo S, Edmondson SG, Casemore DP (1994) Cryptosporidiosis associated with a
swimming pool complex. Communicable Disease Report Review, 4(2): R20–R22.
Hunter PR (1997) Adenoviral infections. Waterborne disease: Epidemiology and ecology. Chichester, John Wiley & Sons.
Jacobson JA (1985) Pool-associated Pseudomonas aeruginosa dermatitis and other bathing-associated infections. Infection Control, 6: 398–401.
Jeppesen C, Bagge L, Jeppesen VF (2000) [Legionella pneumophila in pool water.] Ugeskrift for Laeger, 162:
3592–3594 (in Danish).
Joce RE, Bruce J, Kiely D, Noah ND, Dempster WB, Stalker R, Gumsley P, Chapman PA, Norman P,
Watkins J, Smith HV, Price TJ, Watts D (1991) An outbreak of cryptosporidiosis associated with a swimming pool. Epidemiology and Infection, 107: 497–508.
Johnson LW (1995) Communal showers and the risk of plantar warts. Journal of Family Practice, 40: 136–138.
Kahana LM, Kay JM, Yakrus MA, Waserman S (1997) Mycobacterium avium complex infection in an immunocompetent young adult related to hot tub exposure. Chest, 111: 242–245.
Kamihama T, Kimura T, Hosokawa J-I, Ueji M, Takase T, Tagami K (1997) Tinea pedis outbreak in swimming pools in Japan. Public Health, 111: 249–253.
Kappus KD, Marks JS, Holman RC, Bryant JK, Baker C, Gary GW, Greenberg HB (1982) An outbreak of
Norwalk gastroenteritis associated with swimming in a pool and secondary person to person transmission.
American Journal of Epidemiology, 116: 834–839.
Kee F, McElroy G, Stewart D, Coyle P, Watson J (1994) A community outbreak of echovirus infection
associated with an outdoor swimming pool. Journal of Public Health Medicine, 16: 145–148.
Keene WE, McAnulty JM, Hoesly FC, Williams LP Jr, Hedberg K, Oxman GL, Barrett TJ, Pfaller MA,
Fleming DW (1994) A swimming-associated outbreak of hemorrhagic colitis caused by Escherichia coli
O157:H7 and Shigella sonnei. New England Journal of Medicine, 331(9): 579–584.
Keirn MA, Putnam HD (1968) Resistance of staphylococci to halogens as related to a swimming pool
environment. Health Laboratory Science, 5(3): 180–193.
Khoor A, Leslie KO, Tazelaar HD, Helmers RA, Colby TV (2001) Diffuse pulmonary disease caused by
nontuberculous mycobacteria in immunocompetent people (hot tub lung). American Journal of Clinical
Pathology, 115: 755–762.
56
layout Safe Water.indd 78
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:05
Kidd AH, Jonsson M, Garwicz D, Kajon AE, Wermenbol AG, Verweij XX, de Jong JC (1996) Rapid subgenus identification of human adenovirus isolates. Journal of Clinical Microbiology, 34: 622–627.
Kilvington S, White DG (1994) Acanthamoeba: biology, ecology and human disease. Reviews in Medical
Microbiology, 5: 12–20.
Kilvington S, Mann PG, Warhurst DC (1991) Pathogenic Naegleria amoebae in the waters of Bath: a fatality and its consequences. In: Kellaway GA, ed. Hot springs of Bath. Bath, Bath City Council, pp. 89–96.
Kush BJ, Hoadley AW (1980) A preliminary survey of the association of Ps. aeruginosa with commercial
whirlpool bath waters. American Journal of Public Health, 70: 279–281.
Leoni E, Legnani P, Mucci MT, Pirani R (1999) Prevalence of mycobacteria in a swimming pool environment. Journal of Applied Microbiology, 87: 683–688.
Leoni E, Legnani PP, Bucci Sabattini MA, Righi F (2001) Prevalence of Legionella spp. in swimming pool
environment. Water Research, 35(15): 3749–3753.
Lumb R, Stapledon R, Scroop A, Bond P, Cunliffe D, Goodwin A, Doyle R, Bastian I (2004) Investigation
of spa pools associated with lung disorders caused by Mycobacterium avium complex in immunocompetent
adults. Applied and Environmental Microbiology, 70(8): 4906–4910.
Lykins BW, Goodrich JA, Hoff JC (1990) Concerns with using chlorine-dioxide disinfection in the U.S.A.
Journal of Water Supply: Research and Technology – AQUA, 39: 376–386.
Ma P, Visvesvara GS, Martinez AJ, Theodore FH, Dagget PM, Sawyer TK (1990) Naegleria and Acanthamoeba
infections: review. Reviews of Infectious Diseases, 12: 490–513.
Mahoney FJ, Farley TA, Kelso KY, Wilson SA, Horan JM, McFarland LM (1992) An outbreak of hepatitis
A associated with swimming in a public pool. Journal of Infectious Diseases, 165: 613–618.
Makintubee S, Mallonee J, Istre GR (1987) Shigellosis outbreak associated with swimming. American
Journal of Public Health, 77: 166–168.
Mangione EJ, Huitt G, Lenaway D, Beebe J, Baily A, Figoski M, Rau MP, Albrecht KD, Yakrus MA
(2001) Nontuberculous mycobacterial disease following hot tub exposure. Emerging Infectious Diseases, 7:
1039–1042.
Marston BJ, Lipman HB, Breiman RF (1994) Surveillance for Legionnaires’ disease: Risk factors for morbidity and mortality. Archives of Internal Medicine, 154(21): 2417–2422.
Martinelli F, Carasi S, Scarcella C, Speziani F (2001) Detection of Legionella pneumophila at thermal spas.
New Microbiology, 24: 259–264.
Martinez AJ (1985) Free-living amebas: natural history, prevention, diagnosis, pathology, and treatment of
disease. Boca Raton, FL, CRC Press.
Martinez AJ (1991) Infections of the central nervous system due to Acanthamoeba. Reviews of Infectious
Diseases, 13: S399–S402.
Martinez AJ (1993) Free-living amebas: infection of the central nervous system. Mount Sinai Journal of
Medicine, 60(4): 271–278.
Martinez AJ, Visvesvara GS (1997) Free-living, amphizoic and opportunistic amebas. Brain Pathology,
7(1): 583–598.
Martone WJ, Hierholzer JC, Keenlyside RA, Fraser DW, D’Angelo LJ, Winkler WG (1980) An outbreak
of adenovirus type 3 disease at a private recreation center swimming pool. American Journal of Epidemiology,
111: 229–237.
Mashiba K, Hamamoto T, Torikai K (1993) [A case of Legionnaires’ disease due to aspiration of hot spring
water and isolation of Legionella pneumophila from hot spring water.] Kansenshogaku Zasshi, 67: 163–166
(in Japanese).
Maunula L, Kalso S, von Bonsdorff C-H, Pönkä A (2004) Wading pool water contaminated with both noroviruses and astroviruses as the source of a gastroenteritis outbreak. Epidemiology and Infection, 132: 737–743.
CHAPTER 3.
layout Safe Water.indd 79
MICROBIAL HAZARDS
57
24.2.2006 9:57:05
Mbogo CM, Kahindi S, Githeko AK, Keating J, Kibe L, Githure JI, Beier JC (submitted) Ecology of malaria vectors and culicine abundance in urban Malindi, Kenya. Journal of Vector Ecology.
McAnulty JM, Fleming DW, Gonzalez AH (1994) A community-wide outbreak of cryptosporidiosis associated with swimming at a wave pool. Journal of the American Medical Association, 272: 1597–1600.
McEvoy M, Batchelor N, Hamilton G, MacDonald A, Faiers M, Sills A, Lee J, Harrison T (2000) A cluster
of cases of legionnaires’ disease associated with exposure to a spa pool on display. Communicable Disease
and Public Health, 3(1):43–45.
Moore JE, Heaney N, Millar BC, Crowe M, Elborn JS (2002) Incidence of Pseudomonas aeruginosa in
recreational and hydrotherapy pools. Communicable Disease and Public Health, 5(1): 23–26.
Noguchi H (1918) The survival of Leptospira (Spirochaeta) icterohaemorrhagie in nature: observations concerning micro-chemical reactions and intermediate hosts. Journal of Experimental Medicine, 17: 609–614.
Okhuysen PC, Chappell CL, Crabb JH, Sterling CR, DuPont HL (1999) Virulence of three distinct Cryptosporidium parvum isolates for healthy adults. Journal of Infectious Diseases, 180: 1275–1281.
Oren B, Wende SO (1991) An outbreak of molluscum contagiosum in a kibbutz. Infection, 19: 159–161.
Pai CH, Gordon R, Sims HB, Bryon LE (1984) Sporadic cases of hemorrhagic colitis associated with
Escherichia coli O157:H7. Annals of Internal Medicine, 101: 738–742.
Papapetropoulou M, Vantarakis AC (1998) Detection of adenovirus outbreak at a municipal swimming
pool by nested PCR amplification. Journal of Infection, 36: 101–103.
Petersen C (1992) Cryptosporidiosis in patients with the human immunodeficiency virus. Clinical Infectious Diseases, 15: 903–909.
PHLS (2000) Review of outbreaks of cryptosporidiosis in swimming pools. Marlow, Foundation for Water
Research, Public Health Laboratory Service (DWI0812).
Porter JD, Ragazzoni HP, Buchanon JD, Waskin HA, Juranek DD, Parkin WE (1988) Giardia transmission in a swimming pool. American Journal of Public Health, 78(6): 659–662.
Price D, Ahearn DG (1988) Incidence and persistence of Pseudomonas aeruginosa in whirlpools. Journal of
Clinical Microbiology, 26: 1650–1654.
Public Health Laboratory Service Spa Pools Working Group (1994) Hygiene for spa pools. London, Blackmore Press (ISBN 0 901144 371).
Puech MC, McAnulty JM, Lesjak M, Shaw N, Heron L, Watson JM (2001) A statewide outbreak of cryptosporidiosis in New South Wales associated with swimming at public pools. Epidemiology and Infection,
126: 389–396.
Ratnam S, Hogan K, March SB, Butler RW (1986) Whirlpool-associated folliculitis caused by Pseudomonas
aeruginosa: Report of an outbreak and review. Journal of Clinical Microbiology, 23(3): 655–659.
Rendtorff RC (1954) The experimental transmission of human intestinal protozoan parasites. II. Giardia
lamblia cysts given in capsules. American Journal of Hygiene, 59: 209–220.
Rivera JB, Adera T (1991) Assessing water quality. Staphylococci as microbial indicators in swimming
pools. Journal of Environmental Health, 53(6): 29–32.
Robinton ED, Mood EW (1966) A quantitative and qualitative appraisal of microbial pollution of water
by swimmers: a preliminary report. Journal of Hygiene (London), 64(4): 489–499.
Rocheleau S, Desjardins R, Lafrance P, Briere F (1986) Control of bacteria populations in public pools.
Sciences et Techniques de l’eau, 19: 117–128.
Rose CS, Martyny JW, Newman LS, Milton DK, King TE Jr, Beebe JL, McCammon JB, Hoffman RE,
Kreiss K (1998) “Lifeguard lung”: Endemic granulomatous pneumonitis in an indoor swimming pool.
American Journal of Public Health, 88(12): 1795–1800.
Samples JR, Binder PS, Luibel FJ, Font RL, Visvesvara GS, Peter CR (1984) Acanthamoeba keratitis possibly acquired from a hot tub. Archives of Ophthalmology, 102: 707–710.
58
layout Safe Water.indd 80
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:05
SCA (1995) Methods for the examination of waters and associated materials. Standing Committee of Analysts. London, HMSO.
Seyfried PL, Cook RJ (1984) Otitis externa infections related to Pseudomonas aeruginosa levels in five Ontario lakes. Canadian Journal of Public Health, 75: 83–90.
Sharma S, Srinivasan M, George C (1990) Acanthamoeba keratitis in non-contact lens wearers. Archives of
Ophthalmology, 108: 676–678.
Shaw JH (1984) A retrospective comparison of the effectiveness of bromination and chlorination in controlling Pseudomonas aeruginosa in spas (whirlpools) in Alberta. Canadian Journal of Public Health, 75:
61–68.
Solt K, Nagy T, Csohan A, Csanady M, Hollos I (1994) [An outbreak of hepatitis A due to a thermal spa.]
Budapesti Kozegeszsegugy, 26(1): 8–12 (in Hungarian).
Sorvillo FJ, Waterman SH, Vogt JK, England B (1988) Shigellosis associated with recreational water contact in Los Angeles County. American Journal of Tropical Medicine and Hygiene, 38(3): 613–617.
Sundkist T, Dryden M, Gabb R, Soltanpoor N, Casemore D, Stuart J (1997) Outbreak of cryptosporidiosis associated with a swimming pool in Andover. Communicable Disease Report Review, 7: R190–R192.
Szenasi Z, Endo T, Yagita K, Nagy E (1998) Isolation, identification and increasing importance of ‘freeliving’ amoebae causing human disease. Journal of Medical Microbiology, 47(1): 5–16.
Turner M, Istre GR, Beauchamp H, Baum M, Arnold S (1987) Community outbreak of adenovirus type
7a infections associated with a swimming pool. Southern Medical Journal, 80: 712–715.
van Asperen IA, de Rover CM, Schijven JF, Oetomo SB, Schellekens JF, van Leeuwen NJ, Colle C, Havelaar AH, Kromhout D, Sprenger MW (1995) Risk of otitis externa after swimming in recreational fresh
water lakes containing Pseudomonas aeruginosa. British Medical Journal, 311: 1407–1410.
Visvesvara GS (1999) Pathogenic and opportunistic free-living amebae. In: Murray PR, Baron EJ, Pfaller
MA, Tenover FC, Yolken RH, eds. Manual of clinical microbiology, 7th ed. Washington, DC, ASM Press,
pp. 1383–1384.
Weissman DN, Schuyler MR (1991) Biological agents and allergenic diseases. In: Samet JM, Spengler JD,
eds. Indoor air pollution: a health perspective. Baltimore, MD, Johns Hopkins University Press.
Weyant RS, Bragg SL, Kaufmann AF (1999) Leptospira and leptonema. In: Murray PR, Baron EJ, Pfaller
MA, Tenover FC, Yolken RH, eds. Manual of clinical microbiology, 7th ed. Washington, DC, ASM Press.
WHO (2004) Guidelines for drinking-water quality, 3rd ed., Vol. 1: Recommendations. Geneva, World
Health Organization.
WHO (2005) Legionella and the prevention of legionellosis. Geneva, World Health Organization, in preparation.
Wyn-Jones AP, Sellwood J (2001) Enteric viruses in the aquatic environment. Journal of Applied Microbiology,
91: 945–962.
Yoder JS, Blackburn BG, Craun GF, Hill V, Levy DA, Chen N, Lee SH, Calderon RL, Beach MJ (2004)
Surveillance of waterborne-disease outbreaks associated with recreational water – United States, 2001–
2002. Morbidity and Mortality Weekly Report Surveillance Summaries, 53: 1–22.
CHAPTER 3.
layout Safe Water.indd 81
MICROBIAL HAZARDS
59
24.2.2006 9:57:05
CHAPTER 4
Chemical hazards
C
hemicals found in pool water can be derived from a number of sources: the source
water, deliberate additions such as disinfectants and the pool users themselves (see
Figure 4.1). This chapter describes the routes of exposure to swimming pool chemicals, the chemicals typically found in pool water and their possible health effects.
While there is clearly a need to ensure proper consideration of health and safety
issues for operators and pool users in relation to the use and storage of swimming pool
chemicals, this aspect is not covered in this volume.
Chemicals in pool,
hot tub and spa water
Source water-derived:
disinfection by-products;
precursors
Bather-derived:
urine;
sweat;
dirt;
lotions (sunscreen, cosmetics,
soap residues, etc.)
Management-derived:
disinfectants;
pH correction chemicals;
coagulants
Disinfection by-products:
e.g. trihalomethanes;
haloacetic acids;
chlorate;
nitrogen trichloride
Figure 4.1. Possible pool water contaminants in swimming pools and similar environments
4.1 Exposure
There are three main routes of exposure to chemicals in swimming pools and similar
environments:
• direct ingestion of water;
• inhalation of volatile or aerosolized solutes; and
• dermal contact and absorption through the skin.
60
layout Safe Water.indd 82
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:05
4.1.1 Ingestion
The amount of water ingested by swimmers and pool users will depend upon a range
of factors, including experience, age, skill and type of activity. The duration of exposure will vary significantly in different circumstances, but for adults, extended exposure would be expected to be associated with greater skill (e.g. competitive swimmers), and so there would be a lower rate of ingestion in a comparable time than for
less skilled users. The situation with children is much less clear. There appear to be
no data with which to make a more detailed assessment. A number of estimates have
been made of possible intakes while participating in activities in swimming pools and
similar environments, with the most convincing being a pilot study by Evans et al.
(2001). This used urine sample analysis, with 24-h urine samples taken from swimmers who had used a pool disinfected with dichloroisocyanurate and analysed for
cyanurate concentrations. All the participants swam, but there is no information on
the participant swimming duration. This study found that the average water intake
by children (37 ml) was higher than the intake by adults (16 ml). In addition, the
intake by adult men (22 ml) was higher than that by women (12 ml); the intake by
boys (45 ml) was higher than the intake by girls (30 ml). The upper 95th percentile
intake was for children and was approximately 90 ml. This was a small study, but
the data are of high quality compared with most other estimates, and the estimates,
are based upon empirical data rather than assumptions. In this volume, a ‘worst case’
intake of 100 ml for a child is assumed in calculating ingestion exposure to chemicals
in pool water.
4.1.2 Inhalation
Swimmers and pool users inhale from the atmosphere just above the water’s
surface, and the volume of air inhaled is a function of the intensity of effort and time.
Individuals using an indoor pool also breathe air in the wider area of the building
housing the pool. However, the concentration of pool-derived chemical in the pool
environment will be considerably diluted in open air pools. Inhalation exposure will
be largely associated with volatile substances that are lost from the water surface, but
will also include some inhalation of aerosols, within a hot tub (for example) or where
there is significant splashing. The normal assumption is that an adult will inhale approximately 10 m3 of air during an 8-h working day (WHO, 1999). However, this
will also depend on the physical effort involved. There will, therefore, be significant
individual variation depending upon the type of activity and level of effort.
4.1.3 Dermal contact
The skin will be extensively exposed to chemicals in pool water. Some may have a
direct impact on the skin, eyes and mucous membranes, but chemicals present in pool
water may also cross the skin of the pool, hot tub or spa user and be absorbed into the
body. Two pathways have been suggested for transport across the stratum corneum
(outermost layer of skin): one for lipophilic chemicals and the other for hydrophilic
chemicals (Raykar et al., 1988). The extent of uptake through the skin will depend
on a range of factors, including the period of contact with the water, the temperature
of the water and the concentration of the chemical.
CHAPTER 4.
layout Safe Water.indd 83
CHEMICAL HAZARDS
61
24.2.2006 9:57:06
4.2 Source water-derived chemicals
All source waters contain chemicals, some of which may be important with respect
to pool, hot tub and spa safety. Water from a municipal drinking-water supply may
contain organic materials (such as humic acid, which is a precursor of disinfection
by-products), disinfection by-products (see Section 4.5) from previous treatment/
disinfection processes, lime and alkalis, phosphates and, for chloraminated systems,
monochloramines. Seawater contains high bromide concentrations. In some circumstances, radon may also be present in water that is derived from groundwater. Under
such circumstances, adequate ventilation in indoor pools and hot tubs will be an
important consideration. WHO is considering radon in relation to drinking-water
quality guidelines and other guidance.
4.3 Bather-derived chemicals
Nitrogen compounds, particularly ammonia, that are excreted by bathers (in a number of ways) react with free disinfectant to produce several by-products. A number of
nitrogen compounds can be eluted from the skin (Table 4.1). The nitrogen content
in sweat is around 1 g/l, primarily in the form of urea, ammonia, amino acids and
creatinine. Depending on the circumstances, the composition of sweat varies widely.
Significant amounts of nitrogen compounds can also be discharged into pool water
via urine (Table 4.1). The urine release into swimming pools has been variously estimated to average between 25 and 30 ml per bather (Gunkel & Jessen, 1988) and be
as high as 77.5 ml per bather (Erdinger et al., 1997a), although this area has not been
well researched.
The distribution of total nitrogen in urine among relevant nitrogen compounds
(Table 4.1) has been calculated from statistically determined means of values based on
24-h urine samples. Although more than 80% of the total nitrogen content in urine
is present in the form of urea and the ammonia content (at approximately 5%) is
low, swimming pool water exhibits considerable concentrations of ammonia-derived
compounds in the form of combined chlorine and nitrate. It therefore appears that
there is degradation of urea following chemical reactions with chlorine.
Table 4.1. Nitrogen-containing compounds in sweat and urinea
Sweat
Nitrogencontaining
compounds
Urine
Mean
content
(mg/l)
Portion of total
nitrogen (%)
Mean
content
(mg/l)
Portion of total
nitrogen (%)
Urea
680
68
10 240
84
Ammonia
180
18
560
5
Amino acids
45
5
280
2
Creatinine
7
80
1
8
640
500
5
4
992
100
12 220
100
Other
compounds
Total nitrogen
a
Adapted from Jandik, 1977
62
layout Safe Water.indd 84
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:06
In a study on the fate of chlorine and organic materials in swimming pools using
analogues of body fluids and soiling in a model pool, the results showed that organic
carbon, chloramines and trihalomethanes all reached a steady state after 200–500 h
of operation. Only insignificant amounts of the volatile by-products were found to
be lost to the atmosphere, and only nitrate was found to accumulate, accounting for
4–28% of the dosed amino nitrogen (Judd & Bullock, 2003). No information is
available on concentrations of chemicals in actual swimming pool water from cosmetics, suntan oil, soap residues, etc.
4.4 Management-derived chemicals
A number of management-derived chemicals are added to pool water in order to
achieve the required water quality. A proportion of pool water is constantly undergoing treatment, which generally includes filtration (often in conjunction with coagulation), pH correction and disinfection (see Chapter 5).
4.4.1 Disinfectants
A range of disinfectants are used in swimming pools and similar environments. The
most common are outlined in Table 4.2 (and covered in more detail in Chapter 5).
They are added in order to inactivate pathogens and other nuisance microorganisms.
Chlorine, in one of its various forms, is the most widely used disinfectant.
Some disinfectants, such as ozone and UV, kill or inactivate microorganisms as
the water undergoes treatment, but there is no lasting disinfectant effect or ‘residual’
that reaches the pool and continues to act upon chemicals and microorganisms in the
water. Thus, where these types of disinfection are used, a chlorine- or bromine-type
disinfectant is also employed to provide continued disinfection. The active available
disinfectant in the water is referred to as ‘residual’ or, in the case of chlorine, ‘free’ to
distinguish it from combined chlorine (which is not a disinfectant). In the case of
Table 4.2. Disinfectants and disinfecting systems used in swimming pools and similar environments
Disinfectants used
most frequently in large,
heavily used pools
Disinfectants used
in smaller pools
and hot tubs
Disinfectants used
for small-scale and
domestic pools
Chlorine
• Gas
• Calcium/sodium
hypochlorite
• Electrolytic generation
of sodium hypochlorite
• Chlorinated isocyanurates
(generally outdoor pools)
Bromochlorodimethylhydantoin
(BCDMH)
Chlorine dioxidea
Ozonea
UVa
Bromine
• Liquid bromine
• Sodium bromide +
hypochlorite
Lithium hypochlorite
Bromide/hypochlorite
UVa
UV–ozonea
Iodine
Hydrogen peroxide/
silver/copper
Biguanide
a
Usually used in combination with residual disinfectants (i.e. chlorine- or bromine-based)
CHAPTER 4.
layout Safe Water.indd 85
CHEMICAL HAZARDS
63
24.2.2006 9:57:06
bromine, as the combined form is also a disinfectant, there is no need to distinguish
between the two, so ‘total’ bromine is measured.
The type and form of disinfectant need to be chosen with respect to the specific requirements of the pool. In the case of small and domestic pools, important requirements are
easy handling and ease of use as well as effectiveness. In all cases, the choice of disinfectant
must be made after consideration of the efficacy of a disinfectant under the circumstances
of use (more details are given in Chapter 5) and the ability to monitor disinfectant levels.
1. Chlorine-based disinfectants
Chlorination is the most widely used pool water disinfection method, usually in the
form of chlorine gas, sodium, calcium or lithium hypochlorite but also with chlorinated isocyanurates. These are all loosely referred to as ‘chlorine’.
Practice varies widely around the world, as do the levels of free chlorine that are
currently considered to be acceptable in order to achieve adequate disinfection while
minimizing user discomfort. For example, free chlorine levels of less than 1 mg/l are
considered acceptable in some countries, while in other countries allowable levels may
be considerably higher. Due to the nature of hot tubs (warmer water, often accompanied by aeration and a greater user to water volume ratio), acceptable free chlorine levels tend to be higher than in swimming pools. It is recommended that acceptable levels of free chlorine continue to be set at the local level, but in public and semi-public
pools these should not exceed 3 mg/l and in public/semi-public hot tubs these should
not exceed 5 mg/l. Lower free chlorine concentrations may be health protective when
combined with other good management practices (e.g. pre-swim showering, effective
coagulation and filtration, etc.) or when ozone or UV is also used.
Using high levels of chlorine (up to 20 mg/l) as a shock dose (see Chapter 5) as a
preventive measure or to correct specific problems may be part of a strategy of proper
pool management. While it should not be used to compensate for inadequacies of
other management practices, periodic shock dosing can be an effective tool to maintain microbial quality of water and to minimize build-up of biofilms and chloramines
(see Sections 4.5 and 5.3.4).
Chlorine in solution at the concentrations recommended is considered to be
toxicologically acceptable even for drinking-water; the WHO health-based guideline
value for chlorine in drinking-water is 5 mg/l (WHO, 2004). Concentrations significantly in excess of this may not be of health significance with regard to ingestion (as
no adverse effect level was identified in the study used), even though there might be
some problems regarding eye and mucous membrane irritation. The primary issues
would then become acceptability to swimmers.
The chlorinated isocyanurates are stabilized chlorine compounds, which are widely
used in the disinfection of outdoor or lightly loaded swimming pools. They dissociate
in water to release free chlorine in equilibrium with cyanuric acid. A residual of cyanuric acid and a number of chlorine/cyanuric acid products will be present in the water. The Joint FAO/WHO Expert Committee on Food Additives and Contaminants
(JECFA) has considered the chlorinated isocyanurates with regard to drinking-water
disinfection and proposed a tolerable daily intake (TDI) for anhydrous sodium dichloroisocyanurate (NaDCC) of 0–2 mg/kg of body weight (JECFA, 2004). This would
translate into an intake of 20 mg of NaDCC per day (or 11.7 mg of cyanuric acid per
day) for a 10-kg child. To avoid consuming the TDI, assuming 100 ml of pool water is
64
layout Safe Water.indd 86
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:06
swallowed in a session would mean that the concentration of cyanuric acid/chlorinated
isocyanurates should be kept below 117 mg/l. Levels of cyanuric acid should be kept
between 50 and 100 mg/l in order not to interfere with the release of free chlorine,
and it is recommended that levels should not exceed 100 mg/l. However, although no
comprehensive surveys are available, there are a number of reported measurements of
high levels of cyanuric acid in pools and hot tubs in the USA. Sandel (1990) found
an average concentration of 75.9 mg/l with a median of 57.5 mg/l and a maximum of
406 mg/l. Other studies have reported that 25% of pools (122 of 486) had cyanuric
acid concentrations greater than 100 mg/l (Rakestraw, 1994) and as high as 140 mg/l
(Latta, 1995). Unpublished data from the Olin Corporation suggest that levels up to
500 mg/l may be found. Regular dilution with fresh water (see Chapter 5) is required
in order to keep cyanuric acid at an acceptable concentration.
2. Chlorine dioxide
Chlorine dioxide is not classed as a chlorine-based disinfectant, as it acts in a different
way and does not produce free chlorine. Chlorine dioxide breaks down to chlorite and
chlorate, which will remain in solution; the WHO health-based drinking-water provisional guideline value for chlorite is 0.7 mg/l (based on a TDI of 0.03 mg/kg of body
weight) (WHO, 2004), and this is also the provisional guideline for chlorate. There is
potential for a build-up of chlorite/chlorate in recirculating pool water with time. In order to remain within the TDI levels of chlorate and chlorite, they should be maintained
below 3 mg/l (assuming a 10-kg child and an intake of 100 ml).
3. Bromine-based disinfectants
Liquid bromine is not commonly used in pool disinfection. Bromine-based disinfectants for pools are available in two forms, bromochlorodimethylhydantoin (BCDMH)
and a two-part system that consists of sodium bromide and an oxidizer (usually hypochlorite). As with chlorine-based disinfectants, local practice varies, and acceptable
total bromine may be as high as 10 mg/l. Although there is limited evidence about
bromine toxicity, it is recommended that total bromine does not exceed 2.0–2.5 mg/l.
The use of bromine-based disinfectants is generally not practical for outdoor pools and
spas because the bromine residual is depleted rapidly in sunlight (MDHSS, undated).
There are reports that a number of swimmers in brominated pools develop eye
and skin irritation (Rycroft & Penny, 1983). However, Kelsall & Sim (2001) in a
study examining three different pool disinfection systems (chlorine, chlorine/ozone
and bromine/ozone) did not find that the bromine disinfection system was associated
with a greater risk of skin rashes, although the number of bathers studied was small.
4. Ozone and ultraviolet
Ozone and UV radiation purify the pool water as it passes through the plant room,
and neither leaves residual disinfectant in the water. They are, therefore, used in conjunction with conventional chlorine- and bromine-based disinfectants. The primary
health issue in ozone use in swimming pool disinfection is the leakage of ozone into
the atmosphere from ozone generators and contact tanks, which need to be properly
ventilated to the outside atmosphere. It is also appropriate to include a deozonation
step in the treatment process, to prevent carry-over in the treated water. Ozone is a
severe respiratory irritant, and it is, therefore, important that ozone concentrations in
the atmosphere of the pool building are controlled. The air quality guideline value
CHAPTER 4.
layout Safe Water.indd 87
CHEMICAL HAZARDS
65
24.2.2006 9:57:07
of 0.12 mg/m3 (WHO, 2000) is an appropriate concentration to protect bathers and
staff working in the pool building.
5. Other disinfectants
Other disinfectant systems may be used, especially in small pools. Hydrogen peroxide
used with silver and copper ions will normally provide low levels of the silver and copper ions in the water. However, it is most important that proper consideration is given
to replacement of water to prevent excessive build-up of the ions. A similar situation
would apply to biguanide, which is also used as a disinfectant in outdoor pools.
4.4.2 pH correction
The chemical required for pH value adjustment will generally depend on whether
the disinfectant used is itself alkaline or acidic. Alkaline disinfectants (e.g. sodium
hypochlorite) normally require only the addition of an acid for pH correction, usually
a solution of sodium hydrogen sulfate, carbon dioxide or hydrochloric acid. Acidic
disinfectants (e.g. chlorine gas) normally require the addition of an alkali, usually a
solution of sodium carbonate (soda ash). There should be no adverse health effects
associated with the use of these chemicals provided that they are dosed correctly and
the pH range is maintained between 7.2 and 8.0 (see Section 5.10.3).
4.4.3 Coagulants
Coagulants (e.g. polyaluminium chloride) may be used to enhance the removal of
dissolved, colloidal or suspended material. These work by bringing the material out
of solution or suspension as solids and then clumping the solids together to produce
a floc. The floc is then trapped during filtration.
4.5 Disinfection by-products (DBP)
Disinfectants can react with other chemicals in the water to give rise to by-products (Table
4.3). Most information available relates to the reactions of chlorine, as will be seen from
Tables 4.4–4.11. Although there is potentially a large number of chlorine-derived disinfection by-products, the substances produced in the greatest quantities are the trihalomethanes (THMs), of which chloroform is generally present in the greatest concentration, and
the haloacetic acids (HAAs), of which di- and trichloroacetic acid are generally present in
the greatest concentrations (WHO, 2000). It is probable that a range of organic chloramines could be formed, depending on the nature of the precursors and pool conditions.
Data on their occurrence in swimming pool waters are relatively limited, although they
are important in terms of atmospheric contamination in enclosed pools and hot tubs.
When inorganic bromide is present in the water, this can be oxidized to form
bromine, which will also take part in the reaction to produce brominated by-products
such as the brominated THMs. This means that the bromide/hypochlorite system of
disinfection would be expected to give much higher proportions of the brominated
by-products. Seawater pools disinfected with chlorine would also be expected to show
a high proportion of brominated by-products since seawater contains significant levels
of bromide. Seawater pools might also be expected to show a proportion of iodinated
by-products in view of the presence of iodide in the water. In all pools in which free
halogen (i.e. chlorine, bromine or iodine) is the primary disinfectant, no matter what
form the halogen donor takes, there will be a range of by-products, but these will be
66
layout Safe Water.indd 88
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:07
Table 4.3. Predominant chemical disinfectants used in pool water treatment and their
associated disinfection by-productsa
Disinfectant
Disinfection by-products
Chlorine/hypochlorite
trihalomethanes
haloacetic acids
haloacetonitriles
haloketones
chloral hydrate (trichloroacetaldehyde)
chloropicrin (trichloronitromethane)
cyanogen chloride
chlorate
chloramines
Ozone
bromate
aldehydes
ketones
ketoacids
carboxylic acids
bromoform
brominated acetic acids
Chlorine dioxide
chlorite
chlorate
Bromine/hypochlorite
BCDMH
trihalomethanes, mainly bromoform
bromal hydrate
bromate
bromamines
a
UV is a physical system and is generally not considered to produce by-products
found at significantly lower concentrations than the THMs and HAAs. The use of
ozone in the presence of bromide can lead to the formation of bromate, which can
build up over time without adequate dilution with fresh water (see Chapter 5).
While chlorination has been relatively well studied, it must be emphasized that
data on ozonation by-products and other disinfectants are very limited. Although
those by-products found commonly in ozonated drinking-water would be expected,
there appear to be few data on the concentrations found in swimming pools and
similar environments.
Both chlorine and bromine will react, extremely rapidly, with ammonia in the water, to form chloramines (monochloramine, dichloramine and nitrogen trichloride)
and bromamines (collectively known as haloamines). The mean content of urea and
ammonia in urine is 10 240 mg/l and 560 mg/l, respectively (Table 4.1), but hydrolysis of urea will give rise to more ammonia in the water (Jandik, 1977). Nitrogencontaining organic compounds, such as amino acids, may react with hypochlorite to
form organic chloramines (Taras, 1953; Isaak & Morris, 1980).
During storage, chlorate can build up within sodium hypochlorite solution, and this
can contribute to chlorate levels in disinfected water. However, it is unlikely to be of conCHAPTER 4.
layout Safe Water.indd 89
CHEMICAL HAZARDS
67
24.2.2006 9:57:07
cern to health unless the concentrations are allowed to reach excessive levels (i.e. >3 mg/l),
in which case the efficacy of the hypochlorite is likely to be compromised.
Ozone can react with residual bromide to produce bromate, which is quite stable
and can build up over time (Grguric et al., 1994). This is of concern in drinking-water
systems but will be of lower concern in swimming pools. However, if ozone were
used to disinfect seawater pools, the concentration of bromate would be expected to
be potentially much higher. In addition, bromate is a by-product of the electrolytic
generation of hypochlorite if the brine used is high in bromide. Ozone also reacts
with organic matter to produce a range of oxygenated substances, including aldehydes
and carboxylic acids. Where bromide is present, it can also result in the formation of
brominated products similar to liquid bromine.
More data are required on the impact of UV on disinfection by-products when
used in conjunction with residual disinfectants. UV disinfection is not considered to
produce by-products, and it seems to significantly reduce the levels of chloramines.
4.5.1 Exposure to disinfection by-products
While swimming pools have not been studied to the same extent as drinking-water,
there are some data on the occurrence and concentrations of a number of disinfection by-products in pool water, although the data are limited to a small number of
the major substances. A summary of the concentrations of various prominent organic
by-products of chlorination (THMs, HAAs, haloacetonitriles and others) measured
in different pools is provided in Table 4.4 and Tables 4.9–4.11 below. Many of these
data are relatively old and may reflect past management practices. Concentrations
will vary as a consequence of the concentration of precursor compounds, disinfectant
dose, residual disinfectant level, temperature and pH. The THM found in the greatest
concentrations in freshwater pools is chloroform, while in seawater pools, it is usually
bromoform (Baudisch et al., 1997; Gundermann et al., 1997).
1. Trihalomethanes
Sandel (1990) examined data from 114 residential pools in the USA and reported average concentrations of chloroform of 67.1 µg/l with a maximum value of 313 µg/l. In hot
spring pools, the median concentration of chloroform was 3.8 µg/l and the maximum
was 6.4 µg/l (Erdinger et al., 1997b). Fantuzzi et al. (2001) reported total THM concentrations of 17.8–70.8 µg/l in swimming pools in Italy. In a study of eight swimming
pools in London, Chu & Nieuwenhuijsen (2002) collected and analysed pool water
samples for total organic carbon (TOC) and THMs. They reported a geometric mean1
for all swimming pools of 5.8 mg/l for TOC, 125.2 µg/l for total THMs and 113.3 µg/l
for chloroform; there was a linear correlation between the number of people in the pool
and the concentration of THMs. The pool concentrations of disinfection by-products
will also be influenced by the concentration of THMs and the potential precursor compounds in the source and make-up water.
THMs are volatile in nature and can be lost from the surface of the water, so they
will also be found in the air above indoor pools (Table 4.5). Transport from swimming pool water to the air will depend on a number of factors, including the concentration in the pool water, the temperature and the amount of splashing and surface
1
68
layout Safe Water.indd 90
Mean values in Table 4.4 are arithmetic means.
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:07
disturbance. The concentrations at different levels in the air above the pool will also
depend on factors such as ventilation, the size of the building and the air circulation.
Fantuzzi et al. (2001) examined THM levels in five indoor pools in Italy and found
mean concentrations of total THMs in poolside air of 58.0 µg/m3 ± 22.1 µg/m3 and
concentrations of 26.1 µg/m3 ± 24.3 µg/m3 in the reception area.
Strähle et al. (2000) studied the THM concentrations in the blood of swimmers
compared with the concentrations of THMs in pool water and ambient air (Table
4.6). They showed that intake via inhalation was probably the major route of uptake
of volatile components, since the concentration of THMs in the outdoor pool water
was higher than the concentration in the indoor pool water, but the concentrations in
air above the pool and in blood were higher in the indoor pool than in the outdoor
pool. This would imply that good ventilation at pool level would be a significant
contributor to minimizing exposure to THMs. Erdinger et al. (2004) found that in
a study in which subjects swam with and without scuba tanks, THMs were mainly
taken up by the respiratory pathway and only about one third of the total burden was
taken up through the skin.
Studies by Aggazzotti et al. (1990, 1993, 1995, 1998) showed that exposure to
chlorinated swimming pool water and the air above swimming pools can lead to an
increase in detectable THMs in both plasma and alveolar air, but the concentration in
alveolar air rapidly falls after exiting the pool area (Tables 4.7 and 4.8).
2. Chloramines, chlorite and chlorate
Exposure to chloramines in the atmosphere of indoor pools was studied in France by
Hery et al. (1995) in response to complaints of eye and respiratory tract irritation by
pool attendants. They found concentrations of up to 0.84 mg/m3 and that levels were
generally higher in pools with recreational activities such as slides and fountains.
Erdinger et al. (1999) examined the concentrations of chlorite and chlorate in
swimming pools and found that while chlorite was not detectable, chlorate concentrations varied from 1 mg/l to, in one extreme case, 40 mg/l. Strähle et al. (2000)
found chlorate concentrations of up to 142 mg/l. The concentrations of chlorate
in chlorine-disinfected pools were close to the limit of detection of 1 mg/l, but the
mean concentration of chlorate in sodium hypochlorite-disinfected pools was about
17 mg/l. Chlorate concentrations were much lower in pools disinfected with hypochlorite and ozone, and the chlorate levels were related to the levels in hypochlorite
stock solutions.
3. Other disinfection by-products
A number of other disinfection by-products have been examined in swimming pool
water; these are summarized in Tables 4.9–4.11. Dichloroacetic acid has also been
detected in swimming pool water. In a German study of 15 indoor and 3 outdoor
swimming pools (Clemens & Scholer, 1992), dichloroacetic acid concentrations
averaged 5.6 µg/l and 119.9 µg/l in indoor and outdoor pools, respectively. The mean
concentration of dichloroacetic acid in three indoor pools in the USA was 419 µg/l
(Kim & Weisel, 1998). The difference between the results of these two studies may
be due to differences in the amounts of chlorine used to disinfect swimming pools,
sample collection time relative to chlorination of the water, or addition or exchanges
of water in the pools.
CHAPTER 4.
layout Safe Water.indd 91
CHEMICAL HAZARDS
69
24.2.2006 9:57:07
70
layout Safe Water.indd 92
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:08
14.6
43
198
Germany
121.1
UK
8.3
2.9
2.5
4.5
1.3
4.8
8.9
11.0
22.6
2.3
2.5–23
<1.0–11.4
0.12–15
0.27–25
0.19–4.1
0.69–5.64
1.3–3.4
0.1–150
1.9–16.5
<0.1–54.5
<0.1–1.4
1.6–17.3
4.2–5.4
1–72
1–90
<0.1–105
1.8–2.8
2.7
0.59
1.1
0.4
1.8
1.5
3.0
10.9
0.8
0.67–7
0.03–4.9
0.04–8.8
0.03–0.91
0.03–6.51
<0.1–1
0.1–140
<0.1–3.4
<0.1–1.0
<0.1–16.4
<0.1–15.1
0.78–2.6
<0.1–8
0.3–30
<0.1–48
0.5–10
Disinfection by-product concentration (µg/l)
BDCM
DBCM
Mean
Range
Mean
Range
2.3–14.7
0.2–0.8
BDCM = bromodichloromethane; DBCM = dibromochloromethane
45–212
145–151
.<2–62.3
11.4
Hungary
.3–27.8
1.8–28
8–11
0.51–69
0.69–114
0.82–12
6.4 (max.)
7.1–24.8
2.4–29.8
14.6–111
43–980
0.5–23.6
<0.1–32.9
<0.1–0.9
3.6–82.1
40.6–117.5
4–402
3–580
<0.1–530
19–94
9–179
25–43
Denmark
14.
30.
4.3
3.8
94.9
80.7
74.9
37.9
93.7
33.7
USA
Italy
Country
Poland
Chloroform
Mean
Range
35.9–99.7
Table 4.4. Concentrations of trihalomethanes measured in swimming pool water
0.9
0.16
0.28
0.08
<0.1
<0.1
0.23
1.8
0.1
indoor
indoor
0.67–2 indoor pools
<0.03–8.1
<0.03–3.4
<0.03–0.22
0.02–0.83
<0.1–88
<0.1–3.3
<0.1–0.5
2.4–132
<0.1–4.0
indoor
outdoor
indoor
indoor
hydrotherapy
hydrotherapy
outdoor
indoor
indoor
outdoor
indoor
indoor
indoor
indoor
outdoor
hydrotherapy
spa
indoor pool
indoor
<0.1–1 outdoor
<0.1–60 indoor
<0.1–183 hot tub
indoor
indoor
0.1 indoor
Bromoform
Pool
Mean
Range type
0.2–203.2 indoor
Chu & Nieuwenhuijsen, 2002
Borsányi, 1998
Kaas & Rudiengaard, 1987
Erdinger et al., 1997b
Erdinger et al., 2004
Cammann & Hübner, 1995
Jovanovic et al., 1995
Schössner & Koch, 1995
Stottmeister, 1998, 1999
Puchert et al., 1989
Puchert, 1994
Lahl et al., 1981
Ewers et al., 1987
Eichelsdörfer et al., 1981
Copaken, 1990
Armstrong &
Golden, 1986
Aggazzotti et al., 1993
Aggazzotti et al., 1995
Aggazzotti et al., 1998
Reference
Biziuk et al., 1993
4.5.2 Risks associated with disinfection by-products
The guideline values in the WHO Guidelines for Drinking-water Quality can be used to
screen for potential risks arising from disinfection by-products from swimming pools
and similar environments, while making appropriate allowance for the much lower
quantities of water ingested, shorter exposure periods and non-ingestion exposure. Although there are data to indicate that the concentrations of chlorination by-products
in swimming pools and similar environments may exceed the WHO guideline values
for drinking-water (WHO, 2004), available evidence indicates that for reasonably
well managed pools, concentrations less than the drinking-water guideline values can
be consistently achieved. Since the drinking-water guidelines are intended to reflect
tolerable risks over a lifetime, this provides an additional level of reassurance. Drinking-water guidelines assume an intake of 2 litres per day, but as considered above,
ingestion of swimming pool water is considerably less than this; recent measured data
(Section 4.1.1) indicate an extreme of about 100 ml (Evans et al., 2001). Uptake via
skin absorption and inhalation (in the case of THMs) is proportionally greater than
from drinking-water and is significant, but the low oral intake allows a margin that
can, to an extent, account for this. Under such circumstances, the risks from exposure
to chlorination by-products in reasonably well managed swimming pools would be
considered to be small and must be set against the benefits of aerobic exercise and the
risks of infectious disease in the absence of disinfection.
Levels of chlorate and chlorite in swimming pool water have not been extensively
studied; however, in some cases, high chlorate concentrations have been reported,
which greatly exceeded the WHO provisional drinking-water guideline (0.7 mg/l)
and which would, for a child ingesting 100 ml of water, result in possible toxic effects.
Exposure, therefore, needs to be minimized, with frequent dilution of pool water with
fresh water, and care taken to ensure that chlorate levels do not build up in stored
hypochlorite disinfectants.
The chloramines and bromamines, particularly nitrogen trichloride and nitrogen
tribromide, which are both volatile (Holzwarth et al., 1984), can give rise to significant eye and respiratory irritation in swimmers and pool attendants (Massin et
al., 1998). In addition, nitrogen trichloride has an intense and unpleasant odour at
concentrations in water as low as 0.02 mg/l (Kirk & Othmer, 1993). Studies of subjects using swimming pools and non-swimming attendants have shown a number of
changes and symptoms that appear to be associated with exposure to the atmosphere
in swimming pools. Various authors have suggested that these were associated with
nitrogen trichloride exposure in particular (Carbonnelle et al., 2002; Thickett et al.,
2002; Bernard et al., 2003), although the studies were unable to confirm the specific
chemicals that were the cause of the symptoms experienced. Symptoms are likely to be
particularly pronounced in those suffering from asthma. Yoder et al. (2004) reported
two incidents, between 2001 and 2002, where a total of 52 people were adversely affected by a build-up of chloramines in indoor pool water. One of the incidents related
to a hotel pool, and 32 guests reported coughs, eye and throat irritation and difficulty
in breathing. Both incidents were attributed to chloramines on the basis of the clinical
syndrome and setting. Hery et al. (1995) found that complaints from non-swimmers
were initiated at a concentration of 0.5 mg/m3 chlorine species (expressed in units
of nitrogen trichloride) in the atmosphere of indoor pools and hot tubs. It is recommended that 0.5 mg/m3 would be suitable as a provisional value for chlorine species,
CHAPTER 4.
layout Safe Water.indd 93
CHEMICAL HAZARDS
71
24.2.2006 9:57:08
72
layout Safe Water.indd 94
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:08
Country
049–280
35–195
214
140
169
Aggazzotti et al., 1993
Aggazzotti et al., 1998
indoor1)
indoor
<0.1
<0.1–10
<0.1–10
<0.1–260
<0.1–47
0.23–13
<0.1–1
4.1
0.8
0.9
<0.1–5
<0.1–5
<0.1
0.05–2.9
0.05–3.2
0.08
0.1
<0.03
<0.1–14 indoor
<0.1–14 hot tub3)
3)
<0.1 outdoor3)
<0.03–0.7 indoor2)
<0.03–3.0 indoor1)
outdoor
1.7–136
0.85–16
0.03–0.08
30
4.9
0.05
5.6–206
0.03–0.16
2)
39
0.1
0.4
0.36–2.2
outdoor1)
Armstrong & Golden, 1986
Stottmeister, 1998, 1999
Jovanovic et al., 1995
indoor1)
2)
Lévesque et al., 1994
indoor
indoor
1.2
<0.03
0.2
0.2
Aggazzotti et al., 1995
1)
Reference
indoor1)
Range Pool type
outdoor1)
0.02–0.5
9–14
4–30
0.2
Mean
0.33–9.7
0.1
Range
0.1–14
3.3
0.08–2.0
1.2
3.8
11.4
13.3
6.6
Mean
Bromoform
outdoor1)
5.6
0.21
36
5.6
16–24
2–58
5–100
Range
DBCM
2.3
9.2
20
17.4
19.5
Mean
65
597–1630
Range
66–650
Mean
BDCM
BDCM = bromodichloromethane; DBCM = dibromochloromethane
a
Measured 20 cm above the water surface
b
Measured 150 cm above the water surface
c
Measured 200 cm above the water surface
USA
Germany
Canada
Italy
Chloroform
Disinfection by-product concentration (µg/m3)
Table 4.5. Concentrations of trihalomethanes measured in the air above the pool water surface
Table 4.6. Comparison of trihalomethane concentrations in blood of swimmers after a 1-h
swim, in pool water and in ambient air of indoor and outdoor poolsa
THM concentration (mean, range)
Indoor pool
Outdoor pool
0.48 (0.23–0.88)
0.11 (<0.06–0.21)
19.6 (4.5–45.8)
73.1 (3.2–146)
Air 20 cm above the water surface (µg/m³)
93.6 (23.9–179.9)
8.2 (2.1–13.9)
Air 150 cm above the water surface (µg/m³)
61.6 (13.4–147.1)
2.5 (<0.7–4.7)
Blood of swimmers (µg/l)
Pool water (µg/l)
a
Adapted from Strähle et al., 2000
Table 4.7. Concentrations of trihalomethanes in plasma of 127 swimmersa
THM
No. positive/no. samples
Mean THM
concentration
(µg/l)
Chloroform
Range of THM
concentrations
(µg/l)
127/127
1.06
0.1–3.0
BDCM
25/127
0.14
<0.1–0.3
DBCM
17/127
0.1
<0.1–0.1
a
Adapted from Aggazzotti et al., 1990
Table 4.8. Comparison of trihalomethane levels in ambient air and alveolar air in swimmers prior
to arrival at the swimming pool, during swimming and after swimminga
THM levels (µg/m3) at various monitoring timesb
A
B
C
D
E
Ambient air
20.7 ± 5.3
91.7 ± 15.4
169.7 ± 26.8
20.0 ± 8.4
19.2 ± 8.8
Alveolar air
9.3 ± 3.1
29.4 ± 13.3
76.5 ± 18.6
26.4 ± 4.9
19.1 ± 2.5
Ambient air
n.q.
10.5 ± 3.1
20.0 ± 4.1
n.q.
n.q.
Alveolar air
n.q.
2.7 ± 1.2
6.5 ± 1.3
2.7 ± 1.1
1.9 ± 1.1
n.q.
n.q.
5.2 ± 1.5
0.8 ± 0.8
11.4 ± 2.1
1.4 ± 0.9
n.q.
0.3 ± 0.2
n.q.
0.20 ± 0.1
Ambient air
n.q.
0.2
0.2
0.2
n.q.
Alveolar air
n.q.
n.q.
n.q.
n.q.
n.q.
Chloroform
BDCM
DBCM
Ambient air
Alveolar air
Bromoform
a
Adapted from Aggazzotti et al., 1998
b
Five competitive swimmers (three males and two females) were monitored A: Prior to arrival at the pool; B: After 1 h resting at poolside before swimming; C: After a 1-h swim; D: 1 h after swimming had stopped; and E: 1.5 h after swimming had stopped. D and E
occurred after departing the pool area. n.q. = not quantified
CHAPTER 4.
layout Safe Water.indd 95
CHEMICAL HAZARDS
73
24.2.2006 9:57:09
74
layout Safe Water.indd 96
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:09
2.5–174
2.5–112
32
26
0.06
0.15
0.32
Mean
<0.5–1.7
<0.5–1.9
<0.5–3.3
Range
MBAA
132
8.8
23
Mean
6.2–562
1.8–27
1.5–192
Range
DCAA
0.08
0.64
0.57
Mean
<0.2–1.3
<0.2–4.8
<0.2–7.7
Range
DBAA
hot tub
30
2.3–100 indoor
25–136 indoor
8.2–887 outdoor
1.1–45 hydrotherapy
3.5–199 indoor
Pool
Range type
249
15
42
Mean
TCAA
0.22–57
<0.01–0.02
45
24
0.13–148
13
49
2.5
0.62
2.3
<0.01–16
<0.01–2.8
<0.01–24
Range
1.3
1.5
1.7
Mean
TCAN
Pool
Range type
seawater
indoor
<0.01–10 outdoor
<0.01–7.8 hydrotherapy
<0.01–11 indoor
indoor
DBAN
outdoor
Mean
6.7–18.2
Range
<0.5–2.5
DCAN
9.9
Mean
DCAN = dichloroacetonitrile; DBAN = dibromoacetonitrile; TCAN = trichloroacetonitrile
Germany
Country
Disinfection by-product concentration (µg/l)
Table 4.10. Concentrations of haloacetonitriles measured in swimming pool water
MCAA = monochloroacetic acid; MBAA = monobromoacetic acid; DCAA = dichloroacetic acid; DBAA = dibromoacetic acid; TCAA = trichloroacetic acid
2.6–81
26
Germany
Range
Mean
Country
MCAA
Disinfection by-product concentration (µg/l)
Table 4.9. Concentrations of haloacetic acids measured in swimming pool water
Baudisch et al., 1997
Stottmeister, 1998, 1999
Puchert, 1994
Reference
Mannschott et al., 1995
Lahl et al., 1984
Stottmeister & Naglitsch, 1996
Reference
CHAPTER 4.
layout Safe Water.indd 97
CHEMICAL HAZARDS
75
24.2.2006 9:57:10
Germany
Country
0.03–1.6
0.04–0.78
0.01–10
0.20
1.3
265
0.5–104
230
indoor
seawater
indoor
outdoor
hydrotherapy
indoor
Mannschott et al., 1995
Baudisch et al., 1997
Baudisch et al., 1997
Stottmeister, 1998, 1999
Puchert, 1994
indoor
Reference
outdoor
Pool
Range type
0.32–0.8
Mean
<0.01–0.75
Range
Bromal hydrate
Schöler & Schopp, 1984
Mean
Chloral hydrate
indoor
0.1–2.6
Range
0.32
Mean
Chloropicrin
Disinfection by-product concentration (µg/l)
Table 4.11. Concentrations of chloropicrin, chloral hydrate and bromal hydrate measured in swimming pool water
expressed as nitrogen trichloride, in the atmosphere of indoor swimming pools and
similar environments. However, more specific data are needed on the potential for
exacerbation of asthma in affected individuals, since this is a significant proportion of
the population in some countries. There is also a potential issue regarding those that
are very frequent pool users and who may be exposed for longer periods per session,
such as competitive swimmers. It is particularly important that the management of
pools used for such purposes is optimized in order to reduce the potential for exposure
(Section 5.9).
4.6 Risks associated with plant and equipment malfunction
Chemical hazards can arise from malfunction of plant and associated equipment. This
hazard can be reduced, if not eliminated, through proper installation and effective
routine maintenance programmes. The use of gas detection systems and automatic
shutdown can also be an effective advance warning of plant malfunction. The use of
remote monitoring is becoming more commonplace in after-hours response to plant
and equipment malfunction or shutdown.
4.7 References
Aggazzotti G, Fantuzzi G, Tartoni PL, Predieri G (1990) Plasma chloroform concentration in swimmers
using indoor swimming pools. Archives of Environmental Health, 45A(3): 175–179.
Aggazzotti G, Fantuzzi G, Righi E, Tartoni PL, Cassinadri T, Predieri G (1993) Chloroform in alveolar air
of individuals attending indoor swimming pools. Archives of Environmental Health, 48: 250–254.
Aggazzotti G, Fantuzzi G, Righi E, Predieri G (1995) Environmental and biological monitoring of chloroform in indoor swimming pools. Journal of Chromatography, A710: 181–190.
Aggazzotti G, Fantuzzi G, Righi E, Predieri G (1998) Blood and breath analyses as biological indicators of
exposure to trihalomethanes in indoor swimming pools. Science of the Total Environment, 217: 155–163.
Armstrong DW, Golden T (1986) Determination of distribution and concentration of trihalomethanes in
aquatic recreational and therapeutic facilities by electron-capture GC. LC-GC, 4: 652–655.
Baudisch C, Pansch G, Prösch J, Puchert W (1997) [Determination of volatile halogenated hydrocarbons in
chlorinated swimming pool water. Research report.] Außenstelle Schwerin, Landeshygieneinstitut MecklenburgVorpommern (in German).
Bernard A, Carbonnelle S, Michel O, Higuet S, de Burbure C, Buchet J-P, Hermans C, Dumont X,
Doyle I (2003) Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations
with the attendance in indoor chlorinated swimming pools. Occupational and Environmental Medicine,
60: 385–394.
Biziuk M, Czerwinski J, Kozlowski E (1993) Identification and determination of organohalogen compounds
in swimming pool water. International Journal of Environmental Analytical Chemistry, 46: 109–115.
Borsányi M (1998) THMs in Hungarian swimming pool waters. Budapest, National Institute of Environmental Health, Department of Water Hygiene (unpublished).
Cammann K, Hübner K (1995) Trihalomethane concentrations in swimmers’ and bath attendants’ blood and
urine after swimming or working in indoor swimming pools. Archives of Environmental Health, 50: 61–65.
Carbonnelle S, Francaux M, Doyle I, Dumont X, de Burbure C, Morel G, Michel O, Bernard A (2002)
Changes in serum pneumoproteins caused by short-term exposures to nitrogen trichloride in indoor chlorinated swimming pools. Biomarkers, 7(6): 464–478.
Chu H, Nieuwenhuijsen MJ (2002) Distribution and determinants of trihalomethane concentrations in
indoor swimming pools. Occupational and Environmental Medicine, 59: 243–247.
76
layout Safe Water.indd 98
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:11
Clemens M, Scholer HF (1992) Halogenated organic compounds in swimming pool waters. Zentralblatt
für Hygiene und Umweltmedizin, 193(1): 91–98.
Copaken J (1990) Trihalomethanes: Is swimming pool water hazardous? In: Jolley RL, Condie LW, Johnson JD, Katz S, Minear RA, Mattice JS, Jacobs VA, eds. Water chlorination. Vol. 6. Chelsea, MI, Lewis
Publishers, pp. 101–106.
Eichelsdörfer D, Jandik J, Weil L (1981) [Formation and occurrence of organic halogenated compounds in
swimming pool water.] A.B. Archiv des Badewesens, 34: 167–172 (in German).
Erdinger L, Kirsch F, Sonntag H-G (1997a) [Potassium as an indicator of anthropogenic contamination of
swimming pool water.] Zentralblatt für Hygiene und Umweltmedizin, 200(4): 297–308 (in German).
Erdinger L, Kirsch F, Hoppner A, Sonntag H-G (1997b) Haloforms in hot spring pools. Zentralblatt für
Hygiene und Umweltmedizin. 200: 309–317 (in German).
Erdinger L, Kirsch F, Sonntag H-G (1999) Chlorate as an inorganic disinfection by-product in swimming
pools. Zentralblatt für Hygiene und Umweltmedizin, 202: 61–75.
Erdinger L, Kuhn KP, Kirsch F, Feldhues R, Frobel T, Nohynek B, Gabrio T (2004) Pathways of trihalomethane uptake in swimming pools. International Journal of Hygiene and Environmental Health,
207: 1–5.
Evans O, Cantú R, Bahymer TD, Kryak DD, Dufour AP (2001) A pilot study to determine the water volume
ingested by recreational swimmers. Paper presented to 2001 Annual Meeting of the Society for Risk Analysis,
Seattle, Washington, 2–5 December 2001.
Ewers H, Hajimiragha H, Fischer U, Böttger A, Ante R (1987) [Organic halogenated compounds in swimming pool waters.] Forum Städte-Hygiene, 38: 77–79 (in German).
Fantuzzi G, Righi E, Predieri G, Ceppelli G, Gobba F, Aggazzotti G (2001) Occupational exposure to
trihalomethanes in indoor swimming pools. Science of the Total Environment, 17: 257–265.
Grguric G, Trefry JH, Keaffaber JJ (1994) Ozonation products of bromine and chlorine in seawater
aquaria. Water Research, 28: 1087–1094.
Gundermann KO, Jentsch F, Matthiessen A (1997) [Final report on the research project “Trihalogenmethanes in indoor seawater and saline pools”.] Kiel, Institut für Hygiene und Umweltmedizin der Universität Kiel (in German).
Gunkel K, Jessen H-J (1988) [The problem of urea in bathing water.] Zeitschrift für die Gesamte Hygiene,
34: 248–250 (in German).
Hery M, Hecht G, Gerber JM, Gendree JC, Hubert G, Rebuffaud J (1995) Exposure to chloramines in the
atmosphere of indoor swimming pools. Annals of Occupational Hygiene, 39: 427–439.
Holzwarth G, Balmer RG, Soni L (1984) The fate of chlorine and chloramines in cooling towers. Water
Research, 18: 1421–1427.
Isaak RA, Morris JC (1980) Rates of transfer of active chlorine between nitrogenous substrates. In: Jolley
RL, ed. Water chlorination. Vol. 3. Ann Arbor, MI, Ann Arbor Science Publishers.
Jandik J (1977) [Studies on decontamination of swimming pool water with consideration of ozonation of nitrogen containing pollutants.] Dissertation. Munich, Technical University Munich (in German).
JECFA (2004) Evaluation of certain food additives and contaminants. Sixty-first report of the Joint FAO/
WHO Expert Committee on Food Additives (WHO Technical Report Series No. 922).
Jovanovic S, Wallner T, Gabrio T (1995) [Final report on the research project “Presence of haloforms in pool
water, air and in swimmers and lifeguards in outdoor and indoor pools”.] Stuttgart, Landesgesundheitsamt
Baden-Württemberg (in German).
Judd SJ, Bullock G (2003) The fate of chlorine and organic materials in swimming pools. Chemosphere,
51(9): 869–879.
Kaas P, Rudiengaard P (1987) [Toxicologic and epidemiologic aspects of organochlorine compounds in bathing
water.] Paper presented to the 3rd Symposium on “Problems of swimming pool water hygiene”, Reinhardsbrunn (in German).
CHAPTER 4.
layout Safe Water.indd 99
CHEMICAL HAZARDS
77
24.2.2006 9:57:11
Kelsall HL, Sim MR (2001) Skin irritation in users of brominated pools. International Journal of Environmental Health Research, 11: 29–40.
Kim H, Weisel CP (1998) Dermal absorption of dichloro- and trichloroacetic acids from chlorinated water.
Journal of Exposure Analysis and Environmental Epidemiology, 8(4): 555–575.
Kirk RE, Othmer DF (1993) Encyclopedia of chemical technology, 4th ed. Vol. 5. New York, NY, John Wiley
& Sons, p. 916.
Lahl U, Bätjer K, Duszeln JV, Gabel B, Stachel B, Thiemann W (1981) Distribution and balance of volatile
halogenated hydrocarbons in the water and air of covered swimming pools using chlorine for water disinfection. Water Research, 15: 803–814.
Lahl U, Stachel B, Schröer W, Zeschmar B (1984) [Determination of organohalogenic acids in water
samples.] Zeitschrift für Wasser- und Abwasser-Forschung, 17: 45–49 (in German).
Latta D (1995) Interference in a melamine-based determination of cyanuric acid concentration. Journal of
the Swimming Pool and Spa Industry, 1(2): 37–39.
Lévesque B, Ayotte P, LeBlanc A, Dewailly E, Prud’Homme D, Lavoie R, Allaire S, Levallois P (1994)
Evaluation of dermal and respiratory chloroform exposure in humans. Environmental Health Perspectives,
102: 1082–1087.
Mannschott P, Erdinger L, Sonntag H-P (1995) [Determination of halogenated organic compounds in
swimming pool water.] Zentralblatt für Hygiene und Umweltmedizin, 197: 516–533 (in German).
Massin N, Bohadana AB, Wild P, Héry M, Toamain JP, Hubert G (1998) Respiratory symptoms and bronchial responsiveness in lifeguards exposed to nitrogen trichloride in indoor swimming pools. Occupational
and Environmental Medicine, 55: 258–263.
MDHSS (undated) Swimming pool and spa water chemistry. Missouri Department of Health and Senior Services, Section for Environmental Health (http://www.health.state.mo.us/RecreationalWater/
PoolSpaChem.pdf ).
Puchert W (1994) [Determination of volatile halogenated hydrocarbons in different environmental compartments as basis for the estimation of a possible pollution in West Pommerania.] Dissertation. Bremen, University
of Bremen (in German).
Puchert W, Prösch J, Köppe F-G, Wagner H (1989) [Occurrence of volatile halogenated hydrocarbons in
bathing water.] Acta Hydrochimica et Hydrobiologica, 17: 201–205 (in German).
Rakestraw LF (1994) A comprehensive study on disinfection conditions in public swimming pools in Pinellas
County, Florida. Study conducted by Pinellas County Public Health Unit and The Occidental Chemical
Corporation. Presented on behalf of the Pool Study Team at the NSPI International Expo, New Orleans.
Raykar PV, Fung MC, Anderson BD (1988) The role of protein and lipid domains in the uptake of solutes
by human stratum corneum. Pharmacological Research, 5(3): 140–150.
Rycroft RJ, Penny PT (1983) Dermatoses associated with brominated swimming pools. British Medical
Journal, 287(6390): 462.
Sandel BB (1990) Disinfection by-products in swimming pools and spas. Olin Corporation Research Center
(Report CNHC-RR-90-154) (available from Arch Chemical, Charleston).
Schöler HF, Schopp D (1984) [Volatile halogenated hydrocarbons in swimming pool waters.] Forum
Städte-Hygiene, 35: 109–112 (in German).
Schössner H, Koch A (1995) [Investigations of trihalogenmethane-concentrations in swimming pool water.] Forum Städte-Hygiene, 46: 354–357 (in German).
Stottmeister E (1998) Disinfection by-products in German swimming pool waters. Paper presented to 2nd
International Conference on Pool Water Quality and Treatment, 4 March 1998, School of Water Sciences,
Cranfield University, Cranfield, UK.
Stottmeister E (1999) [Occurrence of disinfection by-products in swimming pool waters.] Umweltmedizinischer Informationsdienst, 2: 21–29 (in German).
78
layout Safe Water.indd 100
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:12
Stottmeister E, Naglitsch F (1996) [Human exposure to other disinfection by-products than trihalomethanes in
swimming pools.] Annual report of the Federal Environmental Agency, Berlin, Germany (in German).
Strähle J, Sacre C, Schwenk M, Jovanovic S, Gabrio T, Lustig B (2000) [Risk assessment of exposure of
swimmers to disinfection by-products formed in swimming pool water treatment.] Final report on the research
project of DVGW 10/95, Landesgesundheitsamt Baden-Württemberg, Stuttgart (in German).
Taras MJ (1953) Effect of free residual chlorination on nitrogen compounds in water. Journal of the American Water Works Association, 45: 4761.
Thickett KM, McCoach JS, Gerber JM, Sadhra S, Burge PS (2002) Occupational asthma caused by chloramines in indoor swimming-pool air. European Respiratory Journal, 19(5): 827–832.
WHO (1999) Principles for the assessment of risks to human health from exposure to chemicals. Geneva, World
Health Organization (Environmental Health Criteria 210).
WHO (2000) Disinfectants and disinfectant by-products. Geneva, World Health Organization (Environmental Health Criteria 216).
WHO (2004) Guidelines for drinking-water quality, 3rd ed. Vol.1. Recommendations. Geneva, World Health
Organization.
Yoder JS, Blackburn BG, Craun GF, Hill V, Levy DA, Chen N, Lee SH, Calderon RL, Beach MJ (2004)
Surveillance of waterborne-disease outbreaks associated with recreational water – United States, 2001–
2002. Morbidity and Mortality Weekly Report, 53(SS08): 1–22.
CHAPTER 4.
layout Safe Water.indd 101
CHEMICAL HAZARDS
79
24.2.2006 9:57:13
CHAPTER 5
Managing water and air quality
T
his chapter builds upon the background provided in Chapters 2, 3 and 4 and
provides guidance relating to water and air quality management (risk management
specific to certain microbial hazards is covered in greater detail in Chapter 3). The
primary water and air quality health challenges to be dealt with are, in typical order
of public health priority:
• controlling clarity to minimize injury hazard;
• controlling water quality to prevent the transmission of infectious disease; and
• controlling potential hazards from disinfection by-products.
All of these challenges can be met through a combination of the following factors:
• treatment (to remove particulates, pollutants and microorganisms), including
filtration and disinfection (to remove/inactivate infectious microorganisms);
• pool hydraulics (to ensure effective distribution of disinfectant throughout the
pool, good mixing and removal of contaminated water);
• addition of fresh water at frequent intervals (to dilute substances that cannot be
removed from the water by treatment);
• cleaning (to remove biofilms from surfaces, sediments from the pool floor and
particulates adsorbed to filter materials); and
• ventilation of indoor pools (to remove volatile disinfection by-products and radon).
Controlling clarity, the most important water quality criterion, involves adequate
water treatment, including filtration. The control of pathogens is typically achieved
by a combination of circulation of pool water through treatment (normally requiring
some form of filtration plus disinfection) and the application of a chemical residual
disinfectant to inactivate microorganisms introduced to the pool itself by, for instance,
bathers. As not all infectious agents are killed by the most frequently used residual
disinfectants, and as circulation through the physical treatment processes is slow, it is
necessary to minimize accidental faecal releases and vomit (and to respond effectively
to them when they occur) and to minimize the introduction of bather-shed organisms by pre-swim hygiene. Microbial colonization of surfaces can be a problem and is
generally controlled through adequate levels of cleaning and disinfection. The control
of disinfection by-products requires dilution, selection of source waters without DBP
precursors (may include water pretreatment if necessary), pre-swim showering, treatment, disinfection modification or optimization and bather education.
Figure 5.1 outlines the components and shows a general layout of a ‘typical’ pool
treatment system. Most pools have a pumped system and water is kept in continuous
80
layout Safe Water.indd 102
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:13
Plant room
Coagulant dosing (5.2)
Strainer
Pump
Filtration (5.4)
Water disinfection (5.3)
alternative disinfection dosing point
pH correction dosing (5.10.3)
Surface water off-take
Balance tank
Dilution (5.5) and
make-up water
Swimming pool
Treated water
Bottom off-take
Figure 5.1. Water treatment processes in a ‘typical pool’ (relevant section numbers are identified
in parentheses)
circulation (see Section 5.6), with fresh water being added for dilution of materials
that are not effectively removed by treatment and to account for losses (often referred
to as make-up water).
5.1 Pre-swim hygiene
In some countries, it is common to shower before a swim. Showering will help to
remove traces of sweat, urine, faecal matter, cosmetics, suntan oil and other potential
water contaminants. Where pool users normally shower before swimming, pool water
is cleaner, easier to disinfect with smaller amounts of chemicals and thus more pleasant to swim in. Money is saved on chemicals (offset to some extent by the extra cost
of heating shower water, where necessary). The most appropriate setup for showers
(e.g. private to encourage nude showering, a continuously run or automatic ‘tunnel’
arrangement) will vary according to country, but pool owners and managers should
actively encourage showering. Showers must run to waste and should be managed to
control Legionella growth (see Chapter 3).
The role of footbaths and showers in dealing with papillomavirus and foot infections is under question. However, it is generally accepted that there must be some
barrier between outdoor dirt and the pool in order to minimize the transfer of dirt
into the pool. A foot spray is probably the best of the alternatives to footbaths. Where
outdoor footwear is allowed poolside (e.g. some outdoor pools), separate poolside
drainage systems can minimize the transfer of pollutants to the pool water.
CHAPTER 5.
layout Safe Water.indd 103
MANAGING WATER AND AIR QUALITY
81
24.2.2006 9:57:14
Toilets should be provided and located where they can be conveniently used before
entering and after leaving the pool. All users should be encouraged to use the toilets
before bathing to minimize urination in the pool and accidental faecal releases. If
babies and toddlers (that are not toilet trained) are allowed in the pool facilities, they
should, wherever possible, wear leak-proof swimwear (that will contain any urine or
faecal release) and, ideally, they should have access only to small pools that can be
completely drained if an accidental faecal release occurs.
5.2 Coagulation
Coagulants (or flocculants) enhance the removal of dissolved, colloidal or suspended material by bringing it out of solution or suspension as solids (coagulation), then
clumping the solids together (flocculation), producing a floc, which is more easily
trapped during filtration. Coagulants are particularly important in helping to remove
the oocysts and cysts of Cryptosporidium and Giardia (Pool Water Treatment Advisorz
Group, pers. comm.; Gregory, 2002), which otherwise may pass through the filter.
Coagulant efficiency is dependent upon pH, which, therefore, needs to be controlled.
5.3 Disinfection
Disinfection is part of the treatment process whereby pathogenic microorganisms
are inactivated by chemical (e.g. chlorination) or physical (e.g. UV radiation) means
such that they represent no significant risk of infection. Circulating pool water is
disinfected during the treatment process, and the entire water body is disinfected by
the application of a residual disinfectant (chlorine- or bromine-based), which partially
inactivates agents added to the pool by bathers. Facilities that are difficult or impossible to disinfect pose a special set of problems and generally require very high rates of
dilution to maintain water quality. For disinfection to occur with any biocidal chemical, the oxidant demand of the water being treated must be satisfied and sufficient
chemical must remain to effect disinfection.
5.3.1 Choosing a disinfectant
Issues to be considered in the choice of a disinfectant and application system include:
• safety (while occupational health and safety are not specifically covered in this
volume, operator safety is an important factor to consider);
• compatibility with the source water (it is necessary to either match the disinfectant to the pH of the source water or adjust the source water pH);
• type and size of pool (e.g. disinfectant may be more readily degraded or lost
through evaporation in outdoor pools);
• ability to remain in water as residual after application;
• bathing load; and
• operation of the pool (i.e. capacity and skills for supervision and management).
The disinfectant used as part of swimming pool water treatment should ideally
meet the following criteria:
• effective and rapid inactivation of pathogenic microorganisms;
• capacity for ongoing oxidation to assist in the control of all contaminants during pool use;
82
layout Safe Water.indd 104
24.2.2006 9:57:14
• a wide margin between effective biocidal concentration and concentrations resulting in adverse effects on human health (adverse health effects of disinfectants and disinfection by-products are reviewed in Chapter 4);
• availability of a quick and easy measurement of the disinfectant concentration
in pool water (simple analytical test methods and equipment); and
• potential to measure the disinfectant concentration online to permit automatic
control of disinfectant dosing and continuous recording of the values measured.
5.3.2 Characteristics of various disinfectants
1. Chlorine-based disinfectants
Chlorination is the most widely used pool water disinfection method, usually in the
form of chlorine gas, a hypochlorite salt (sodium, calcium, lithium) or chlorinated
isocyanurates. While chlorine gas can be safely and effectively used, it does have the
potential to cause serious health impacts, and care must be taken to ensure that health
concerns do not arise.
When chlorine gas or hypochlorite is added to water, hypochlorous acid (HOCl)
is formed. Hypochlorous acid dissociates in water into its constituents H+ and OCl–
(hypochlorite ion), as follows:
HOCl
hypochlorous
acid
↔
H+
hydrogen
ion
+
OCl–
hypochlorite
ion
The degree of dissociation depends on pH and (much less) on temperature. Dissociation is minimal at pH levels below 6. At pH levels of 6.5–8.5, a change occurs from
undissociated hypochlorous acid to nearly complete dissociation. Hypochlorous acid
is a much stronger disinfectant than hypochlorite ion. At a pH of 8.0, 21% of the free
chlorine exists in the hypochlorous acid form (acting as a strong, fast, oxidizing disinfectant), while at a pH of 8.5, only 12% of that chlorine exists as hypochlorous acid.
For this reason, the pH value should be kept relatively low and within defined limits
(7.2–7.8 – see Section 5.10.3). Together, hypochlorous acid and OCl– are referred
to as free chlorine. The usual test for chlorine detects both free and total chlorine; to
determine the effectiveness of disinfection, the pH value must also be known.
The chlorinated isocyanurate compounds are white crystalline compounds with a
slight chlorine-type odour that provide free chlorine (as hypochlorous acid) when dissolved in water but which serve to provide a source of chlorine that is more resistant to
the effects of UV light. They are widely used in outdoor or lightly loaded pools. They
are an indirect source of chlorine, and the reaction is represented by the equation:
ClxH3–xCy
+
H2O
chloroisowater
cyanurates
x = 1 (mono-); 2 (di-); 3 (tri-)
↔
C3H3N3O
cyanuric
acid
+
HOCl
hypochlorous
acid
Free chlorine, cyanuric acid and chlorinated isocyanurate exist in equilibrium.
The relative amounts of each compound are determined by the pH and free chlorine
CHAPTER 5.
layout Safe Water.indd 105
MANAGING WATER AND AIR QUALITY
83
24.2.2006 9:57:14
concentration. As the disinfectant (HOCl) is used up, more chlorine atoms are released
from the chloroisocyanurates to form hypochlorous acid. This results in an enrichment
of cyanuric acid in the pool that cannot be removed by the water treatment process.
Dilution with fresh water is necessary to keep the cyanuric acid concentration at a
satisfactory level.
The balance between free chlorine and the level of cyanuric acid is critical and can
be difficult to maintain. If the balance is lost because cyanuric acid levels become too
high, unsatisfactory microbial conditions can result. Cyanuric acid in chlorinated
water (whether introduced separately or present through the use of chlorinated isocyanurates) will reduce the amount of free chlorine. At low levels of cyanuric acid, there
is very little effect; as the cyanuric acid level increases, however, the disinfecting and
oxidizing properties of the free chlorine become progressively reduced. High levels of
cyanuric acid cause a situation known as ‘chlorine lock’, when even very high levels
of chlorine become totally locked with the cyanuric acid (stabilizer) and unavailable
as disinfectant; however, this does not occur below cyanuric acid levels of 200 mg/l.
It means, however, that the cyanuric acid level must be monitored and controlled
relative to chlorine residual, and it is recommended that cyanurate levels should not
exceed 100 mg/l. A simple turbidity test, where the degree of turbidity, following
addition of the test chemical, is proportional to the cyanuric acid concentration, can
be used to monitor levels. For effective disinfection, the pH value must also be monitored, because the influence of pH on disinfection efficiency is the same as described
for chlorine as a disinfectant.
2. Bromine-based disinfectants
Elemental bromine is a heavy, dark red-brown, volatile liquid with fumes that are
toxic and irritating to eyes and respiratory tract, and it is not considered suitable for
swimming pool disinfection.
Bromine combines with some water impurities to form combined bromine, including bromamines. However, combined bromine acts as a disinfectant and produces less sharp and offensive odours than corresponding chloramines. Bromine does not
oxidize ammonia and nitrogen compounds. Because of this, bromine cannot be used
for shock dosing. When bromine disinfectants are used, shock dosing with chlorine
is often necessary to oxidize ammonia and nitrogen compounds that eventually build
up in the water (MDHSS, undated). Hypobromous acid reacts with sunlight and
cannot be protected from the effects of UV light by cyanuric acid or other chemicals,
and thus it is more practical to use bromine disinfectants for indoor pools.
For pool disinfection, bromine compounds are usually available in two forms, both
of which are solids:
• a one-part system that is a compound (bromochlorodimethylhydantoin –
BCDMH) of both bromine and chlorine, each attached to a nitrogen atom of
dimethylhydantoin (DMH) as organic support for the halogens; and
• a two-part system that uses a bromide salt dissolved in water, activated by addition of a separate oxidizer.
BCDMH is an organic compound that dissolves in water to release hypobromous
acid (HOBr) and hypochlorous acid. The latter reacts with bromide (Br–) (formed by a
reduction of hypobromous acid) to form more hypobromous acid:
84
layout Safe Water.indd 106
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:15
Br-(DMH)-Cl + 2 H2O
bromochlorowater
dimethylhydantoin
disinfection
HOBr
oxidation
HOCl + Br–
↔
HOBr
hypobromous
acid
+
HOCl
+ H-(DMH)-H
hypochlorous
dimethylacid
hydantoin
Br–
HOBr + Cl–
It can, therefore, be used both for treatment (oxidation) and to provide a residual
disinfectant. Like the chlorinated isocyanurates, failure to maintain the correct relationship between the disinfectant residual and the organic component can result
in unsatisfactory microbial conditions. The level of dimethylhydantoin in the water
must be limited and should not exceed 200 mg/l. There is no poolside test kit available, and the need to regularly monitor dimethylhydantoin by a qualified laboratory
is a disadvantage of the use of BCDMH. On the other hand, BCDMH is relatively
innocuous in storage, is easy to dose and often does not need pH correction (as it is
nearly neutral and has little effect on the pH values of most water). It is mostly available as tablets, cartridges or packets. BCDMH has a long shelf life and dissolves very
slowly, so it may be used in floating and erosion-type feeders.
The two-part bromine system consists of a bromide salt (sodium bromide) and an
oxidizer (hypochlorite, ozone). The sodium bromide is dosed to the water, passing
through the treatment processes, upstream of the oxidizer, which is added to activate
the bromide into hypobromous acid:
Br– + oxidizer
HOBr
Disinfectant action returns hypobromous acid to bromide ions, which can again
be reactivated. The pH value should be between 7.8 and 8.0 using this disinfection
system (see also Section 5.10.3).
3. Ozone
Ozone can be viewed as the most powerful oxidizing and disinfecting agent that is
available for pool water treatment (Rice, 1995; Saunus, 1998); it is generated on site
and is potentially hazardous, particularly to the plant room operators. It is unsuitable
for use as a residual disinfectant, as it readily vaporizes, is toxic and is heavier than air,
leading to discomfort and adverse health effects (Locher, 1996). Ozonation is, therefore, followed by deozonation and addition of a residual disinfectant (i.e. chlorine- or
bromine-based disinfectants).
All of the circulating water is treated with sufficient amounts of ozone (between
0.8 and 1.5 g/m3, depending on the water temperature) to satisfy the oxidant demand
of the water and attain a residual of dissolved ozone for several minutes. Under these
conditions, ozone oxidizes many impurities (e.g. trihalomethane [THM] precursors)
and microorganisms (disinfection), thereby reducing subsequent residual disinfectant
requirements within the pool water. Lower disinfectant demand allows the pool operator to achieve the desired residual with a lower applied chlorine (or bromine) dose. As
ozone can be inhaled by pool users and staff, excess ozone must be destroyed (forming
oxygen and carbon dioxide) by deozonation (using granular activated carbon, activated
CHAPTER 5.
layout Safe Water.indd 107
MANAGING WATER AND AIR QUALITY
85
24.2.2006 9:57:15
heat-treated anthracite or thermal destruction), and an ozone leakage detector should
be installed in the plant room. As residual disinfectants would also be removed by the
deozonation process, they are, therefore, added after this. Microbial colonization of the
deozonation media (especially granular activated carbon) can occur; this can be avoided
by ensuring that there is residual disinfectant in the incoming water stream from the
pool, maintaining the correct filter bed depth and an appropriate filter velocity.
Chloramines are oxidized by ozone into chloride and nitrate (Eichelsdörfer &
Jandik, 1979, 1984), and precursors of disinfection by-products are also destroyed,
resulting in very low levels of THMs (<0.02 mg/l) (Eichelsdörfer et al., 1981; Eichelsdörfer, 1987) and other chlorinated organics. The use of ozone in conjunction with
chlorine (to ensure a residual disinfectant throughout the pool or similar environment) is, however, considerably more expensive than that of chlorine alone.
An ozone system in combination with BCDMH is also in use. However, the practice
is to add only small amounts of ozone to this system to oxidize only the bromide (resulting from the spent hypobromous acid) back to hypobromous acid. Therefore, this
BCDMH/ozone combination allows less BCDMH to be added. Ozone can also be used
in combination with sodium bromide, as described above, as an oxidizer.
4. Ultraviolet (UV) radiation
Like ozone, the UV radiation process purifies the circulating water, without leaving a residual disinfectant. It inactivates microorganisms and breaks down some pollutants (e.g.
chloramines) by photo-oxidation, decreasing the oxidant demand of the purified water.
UV disinfection can be achieved by UV irradiation at wavelengths between 200
and 300 nm. The following criteria are important in the selection of an appropriate
UV system:
•
•
•
•
•
•
type of microorganisms to be destroyed;
water flow rate to be treated;
type of lamps (low or medium pressure);
UV dose;
water temperature; and
rate of disinfection.
For UV to be most effective, the water must be pretreated to remove turbidity-causing
particulate matter that prevents the penetration of the UV radiation or
absorbs the UV energy (Saunus, 1998). The UV lamps need to be cleaned periodically, as substances that build up on the lamps will reduce their pathogen inactivation
efficiency over time. As with ozone, it is also necessary to use a chlorine- or brominebased disinfectant to provide a residual disinfectant in the pool.
5. Algicides
Algicides are used to control algal growths, especially in outdoor pools. Algal growth
is possible only if the nutrients phosphate, nitrogen and potassium are present in the
pool water. Phosphate can be removed from the pool water by good coagulation and
filtration during water treatment. Algal growth is best controlled by ensuring effective
coagulation/filtration and good hydraulic design. In such properly managed swimming pools, the use of algicidal chemicals for the control of algae is not necessary
(Gansloser et al., 1999). If problems persist, however, then proprietary algicides can
86
layout Safe Water.indd 108
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:15
be used. Quaternary ammonium and polyoximino compounds and copper salts can
be used, but any based on mercury (a cumulative toxic heavy metal) should not be
added to swimming pools. All should be used in strict accordance with the suppliers’
instructions and should be intended for swimming pool use.
5.3.3 Disinfection by-products (DBP)
The production of disinfection by-products (see Chapter 4) can be controlled to a
significant extent by minimizing the introduction of precursors though source water
selection, good bather hygienic practices (e.g. pre-swim showering – see Section 5.1),
maximizing their removal by well managed pool water treatment and replacement
of water by the addition of fresh supplies (i.e. dilution of chemicals that cannot be
removed). It is inevitable, however, that some volatile disinfection by-products, such
as chloroform and nitrogen trichloride (a chloramine), may be produced in the pool
water (depending upon the disinfection system used) and escape into the air. While
levels of production should be minimized, this hazard can also be managed to some
extent through good ventilation (see also Section 5.9).
5.3.4 Disinfectant dosing
The method of introducing disinfectants to the pool water influences their effectiveness,
and, as illustrated in Figure 5.1, disinfectant dosing may occur pre- or post-filtration.
Individual disinfectants have their own specific dosing requirements, but the following
principles apply to all:
• Automatic dosing is preferable: electronic sensors monitor pH and residual disinfectant levels continuously and adjust the dosing correspondingly to maintain
correct levels. Regular verification of the system (including manual tests on pool
water samples) and good management are important. Section 5.10 describes the
monitoring procedures.
• Hand-dosing (i.e. putting chemicals directly into the pool) is rarely justified.
Manual systems of dosing must be backed up by good management of operation and monitoring. If manual dosing is employed, it is important that the
pool is empty of bathers until the chemical has dispersed.
• Dosing pumps should be designed to shut themselves off if the circulation system fails (although automatic dosing monitors should remain in operation) to
ensure that chemical dispersion is interrupted. If chemical dosing continues
without water circulating, then high local concentrations of the dosed chemical
will occur. On resumption of the circulation system, the high concentration
will progress to the pool. If, for example, both hypochlorite and acid have been
so dosed, the resultant mix containing chlorine gas may be dangerous to pool
users.
• Residual disinfectants are generally dosed at the end of the treatment process.
The treatment methods of coagulation, filtration and ozonation or ultraviolet serve to clarify the water, reduce the organic load (including precursors for
the formation of disinfection by-products) and greatly reduce the microbial
content, so that the post-treatment disinfection can be more effective and the
amount of disinfectant required is minimized.
CHAPTER 5.
layout Safe Water.indd 109
MANAGING WATER AND AIR QUALITY
87
24.2.2006 9:57:16
• It is important that disinfectants and pH-adjusting chemicals are well mixed
with the water at the point of dosing.
• Dosing systems, like circulation, should operate 24 h a day.
Shock dosing
• Using a shock dose of chlorine as a preventive measure or to correct specific
problems may be part of a strategy of proper pool management. Shock dosing is used to control a variety of pathogens and nuisance microorganisms
and to destroy organic contaminants and chloramine compounds. Destroying chloramines requires free chlorine levels at least 10 times the level of combined chlorine. As a preventive measure, routine shock dosing (which is practised in some countries) typically involves raising free chlorine levels to at least
10 mg/l for between 1 and 4 h. Intervention shock dosing for a water quality problem (such as an accidental faecal release) may involve raising the free
chlorine residual to 20 mg/l for an 8-h period while the pool is empty (see
Section 5.8).
• Trying to compensate for inadequacies in treatment by shock dosing is bad
practice, because it can mask deficiencies in design or operation that may produce other problems.
• If not enough chlorine is added, the combined chlorine (chloramines) problem
may be exacerbated, and conjunctival irritation and obnoxious odours in the
pool area may be raised to high levels. If too much chlorine is added, it may
take a long time to drop to safe levels before bathing can be resumed. Chlorine
levels should return to acceptable levels (i.e. <5 mg/l – see Section 4.4.1) before
bathers are permitted in the pool.
5.4 Filtration
The primary function of filtration is to remove turbidity to achieve appropriate water
clarity. Water clarity is a key factor in ensuring the safety of swimmers. Poor underwater visibility is a contributing factor to injuries (Chapter 2) and can seriously hamper
recognition of swimmers in distress or a body lying on the bottom of the pool.
Disinfection will also be compromised by particulates. Particles can shield microorganisms from the action of disinfectants. Alternatively, the disinfectants may react
with certain components of organic particles to form complexes that are less effective
than the parent compounds, or the disinfectants may oxidize the organic material,
thereby eliminating disinfection potential. Filtration is often the critical step for the
removal of Cryptosporidium oocysts and Giardia cysts (see Section 3.3). Filtration is
also effective against microbes, notably free-living amoebae, that harbour opportunistic bacteria such as Legionella and Mycobacterium species.
5.4.1 Filter types
There are a number of types of filter available, and the choice of filter will be based
on several factors, including:
• the quality of the source water;
• the amount of filter area available and number of filters> Pools benefit greatly
from the increased flexibility and safeguards of having more than one filter;
88
layout Safe Water.indd 110
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:16
• filtration rate: Typically, the higher the filtration rate, the lower the filtration
efficiency;
• ease of operation;
• method of backwashing: The cleaning of a filter bed clogged with solids is referred to as backwashing. It is accomplished by reversing the flow, fluidizing
the filter material and passing pool water back through the filters to waste.
Backwashing should be done as recommended by the filter manufacturer, when
the allowable turbidity value has been exceeded, when a certain length of time
without backwashing has passed or when a pressure differential is observed; and
• degree of operator training required.
1. Cartridge filters
Cartridge filters can nominally filter down to 7 µm and last up to two years. The filter
medium is spun-bound polyester or treated paper. Cleaning is achieved by removing
the cartridge and washing it. Their main advantage is the relatively small space requirement compared with other filter types, and they are often used with small pools
and hot tubs.
2. Sand filters
Medium-rate sand filters can nominally filter down to about 7 µm in size with the
addition of a suitable coagulant (such as polyaluminium chloride or aluminium hydroxychloride). Cleaning is achieved by manual reverse flow backwashing, with air
scouring to remove body oils and fats to improve the backwash efficiency. For indoor
heated pools, the sand medium typically has a life of between five and seven years.
Medium-rate sand filters are comparatively large-diameter pressure vessels (in a horizontal or vertical format) and require large plant rooms. Drinking-water treatment
has shown that when operated with a coagulant, sand filters can remove over 99% of
Cryptosporidium oocysts. Studies in a pilot sand filtration plant under swimming pool
filtration conditions have shown that without the addition of coagulant, removal of
the Cryptosporidium oocyst surrogate (fluorescent polystyrene particles sized between
1 and 7 µm) was less than 50%. Using coagulants, polyaluminium chloride and polyaluminium silicate sulfate improved the removal up to 99% (Pool Water Treatment
Advisory Group, pers. comm.).
3. Ultrafine filters
Ultrafine precoat filters (UFF) use a replaceable filter medium that is added after each
backwash. Filter media include diatomaceous earth, diatomite products and perlite.
The benefit of precoat filtration is that it can provide a particle removal of 1–2 µm
and, as such, provide good removal of Cryptosporidium oocysts. Table 5.1 compares
the alternative filter types.
5.4.2 Turbidity measurement
Turbidity is a measure of the amount of suspended matter in water, and the more
turbid the water, the less clarity. Turbidity needs to be controlled both for safety and
for effective disinfection. For identifying bodies at the bottom of the pool, a universal
turbidity value is not considered to be appropriate, as much depends on the characteristics of the individual pool, such as surface reflection and pool material/construction. Individual standards should be developed, based on risk assessment at each pool,
CHAPTER 5.
layout Safe Water.indd 111
MANAGING WATER AND AIR QUALITY
89
24.2.2006 9:57:16
Table 5.1. Comparison of filter types
Criteria
Common filter sizes
Design filter flow rate
Cleaning flow rate
Cleaning
Average wash water
Filter aid
Cleaning implications
Particulate collection
Nominal particle removal
UFF
Up to 46 m2
3–5 m3/m2/h
5 m3/m2/h
Backwash and media
replacement
0.25 m3/m2 pool water
None
A backwash tank may
be required. Separation
tank required to collect
used filter media with
periodic sludge removal
Surface
1–2 µm
Pressure rise for backwash 70 kPa
Comparative running costs High
Comparative installation
High
costs
Filter type
Medium-rate sand
Up to 10 m2
25–30 m3/m2/h
37–42 m3/m2/h
Backwash
Cartridge
Up to 20 m2
1.5 m3/m2/h
Not applicable
Manual, hose down
2.5 m3/m2 pool water
Optional coagulants
A backwash tank
may be required
0.02 m3/m2 mains water
None
Hose-down and waste
drain facility
Depth
10 µm, 7 µm with
coagulant
40 kPa
Low
High
Degree of depth
7 µm
40 kPa
Medium
Low
UFF = ultrafine filter
but it is recommended that, as a minimum, it should be possible to see a small child
at the bottom of the pool from the lifeguard position while the water surface is in
movement, as in normal use. An alternative is to maintain water clarity so that lane
markings or other features on the pool bottom at its greatest depth are clearly visible
when viewed from the side of the pool. Operators could determine these indicators as
a turbidity equivalent through experience and then monitor routinely for turbidity.
In terms of effective disinfection, a useful, but not absolute, upper-limit guideline for
turbidity is 0.5 nephelometric turbidity unit (NTU), determined by the nephelometric method (ISO, 1999).
5.5 Dilution
Coagulation, filtration and disinfection will not remove all pollutants. Swimming
pool design should enable the dilution of pool water with fresh water. Dilution limits
the build-up of pollutants from bathers (e.g. constituents of sweat and urine), of byproducts of disinfection and of various other dissolved chemicals. Dilution rates need
to account for the replacement of water used in filter backwashing, evaporation and
splash-out. As a general rule, the addition of fresh water to disinfected pools should
not be less than 30 litres per bather.
5.6 Circulation and hydraulics
The purpose of paying close attention to circulation and hydraulics is to ensure that
the whole pool is adequately served by filtered, disinfected water. Treated water must
90
layout Safe Water.indd 112
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:17
get to all parts of the pool, and polluted water must be removed – especially from
areas most used and most polluted by bathers. It is recommended that 75–80% be
taken from the surface (where the pollution is greatest – Gansloser et al., 1999), with
the remainder taken from the bottom of the pool. The bottom returns allow the
removal of grit and improved circulation within the pool. Without good circulation
and hydraulics, even water treatment may not give adequate pool water quality.
The circulation rate is defined as the flow of water to and from the pool through all
the pipework and the treatment system. The appropriate circulation rate depends, in
most cases, on bathing load. There are, however, some types of pool where circulation
rate cannot realistically be derived from bathing load – diving pools and other waters
more than 2 m deep, for example, where the bathing load relative to water volume
may be very low. Circulation rate is related to turnover period, which is the time taken
for a volume of water equivalent to the entire pool water volume to pass through the
filters and treatment plant and back to the pool. Turnover periods must, however, also
suit the particular type of pool (see Box 5.1 for an example of guidance); this is related
to the likely pollution load based on the type of activity undertaken and the volume
of water within the pool. Where pools have moveable floors, the turnover should be
calculated based upon the shallowest depth achievable. Formulae are available for
calculating turnover rates, and these should be employed at the design stage. Box 5.1
gives some examples of turnover periods that have been employed in the UK.
BOX 5.1 EXAMPLES OF TURNOVER PERIODS FOR DIFFERENT TYPES OF POOLS
In the United Kingdom (BSI, 2003), the following turnover periods for different types of pools have
been recommended:
Pool type
Turnover period
Competition pools 50 m long
Conventional pools up to 25 m long with 1-m shallow end
Diving pools
Hydrotherapy pools
Leisure water bubble pools
Leisure waters up to 0.5 m deep
Leisure waters 0.5–1 m deep
Leisure waters 1–1.5 m deep
Leisure waters over 1.5 m deep
Teaching/learner/training pools
Water slide splash pools
3–4 h
2.5–3 h
4–8 h
0.5–1 h
5–20 min
10–45 min
0.5–1.25 h
1–2 h
2–2.5 h
0.5–1.5 h
0.5–1 h
5.7 Bathing load
Bathing load is a measure of the number of people in the pool. For a new pool, the
bathing load should be estimated at the design stage.
There are many factors that determine the maximum bathing load for a pool; these
include:
• area of water – in terms of space for bathers to move around in and physical safety;
• depth of water – the deeper the water, the more actual swimming there is and
the more area a bather requires;
CHAPTER 5.
layout Safe Water.indd 113
MANAGING WATER AND AIR QUALITY
91
9.3.2006 15:31:08
• comfort; and
• pool type and bathing activity.
Pool operators need to be aware of the maximum bathing load and should ensure
that it is not exceeded during the operation of the pool. Where the maximum bathing
load has not been established, it has been suggested in the UK that the figures in Table
5.2 (BSI, 2003) can provide an approximation. These figures may not be appropriate
for all pool types or all countries.
Table 5.2. An example of maximum bathing loadsa
Water depth
<1.0 m
1.0–1.5 m
>1.5 m
a
Maximum bathing load
1 bather per 2.2 m2
1 bather per 2.7 m2
1 bather per 4.0 m2
Adapted from BSI, 2003
5.8 Accidental release of faeces or vomit into pools
Accidental faecal releases may occur relatively frequently, although it is likely that most
go undetected. Accidental faecal releases into swimming pools and similar environments
can lead to outbreaks of infections associated with faecally-derived viruses, bacteria and
pathogenic protozoa (Chapter 3); vomit may have a similar effect. A pool operator
faced with an accidental faecal release or vomit in the pool water must, therefore, act
immediately.
If the faecal release is a solid stool, it should simply be retrieved quickly and discarded
appropriately. The scoop used to retrieve it should be disinfected so that any bacteria
and viruses adhering to it are inactivated and will not be returned to the pool the next
time the scoop is used. As long as the pool is, in other respects, operating properly (i.e.
disinfectant levels are maintained), no further action is necessary. The same applies to
solid animal faeces.
If the stool is runny (diarrhoea) or if there is vomit, the situation is more likely to be
hazardous, as the faeces or vomit is more likely to contain pathogens. Even though most
disinfectants deal relatively well with many bacterial and viral agents in accidental faecal
releases and vomit, the possibility exists that the diarrhoea or vomit is from someone infected with one of the protozoan parasites, Cryptosporidium and Giardia. The infectious
stages (oocysts/cysts) are resistant to chlorine disinfectants in the concentrations that are
practical to use. The pool should therefore be cleared of bathers immediately.
The safest action, if the incident has occurred in a small pool or hot tub, is to empty
and clean it before refilling and reopening. However, this is practically impossible in
many larger pools, for reasons of cost and extended periods of closure. If draining down
is not possible, then a procedure based on the one given below should be followed (it
should be noted, however, that this is an imperfect solution that will only reduce but
not eliminate risk):
• The pool should be cleared of people immediately.
• As much of the material as possible should be collected, removed and disposed
of to waste; this may be done through netting, sweeping and/or vacuuming
(provided the equipment can be adequately disinfected after use).
92
layout Safe Water.indd 114
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:17
• Disinfectant levels should be maintained at the top of the recommended range
or chlorination to 20 mg/l at pH 7.2–7.5 for 8 h (shock dosing) should be
performed.
• Using a coagulant (if appropriate), the water should be filtered for six turnover
cycles; this may mean closing the pool until the next day.
• The filter should be backwashed (and the water run to waste).
• The final residual disinfectant level and pH value should be checked, and if
satisfactory, then the pool can be reopened.
The willingness of operators and lifeguards to act is critical. Pool operators are unlikely to know with certainty what has caused a diarrhoea incident, and a significant
proportion of such diarrhoea incidents may happen without lifeguards being aware
of them. The most important contribution a pool operator can make to the problem
is to guard against it. There are a few practical actions pool operators can take to help
prevent faecal release into pools:
• No child (or adult) with a recent history of diarrhoea should swim.
• Parents should be encouraged to make sure their children use the toilet before
they swim, and babies and toddlers that have not been toilet trained should ideally wear waterproof nappies or specially designed bathing wear.
• Young children should whenever possible be confined to pools small enough to
drain in the event of an accidental release of faeces or vomit.
• Lifeguards should be made responsible for looking out for and acting on accidental faecal release/vomit incidents.
5.9 Air quality
Air quality in indoor swimming pool facilities is important for a number of reasons,
including:
• Staff and user health. The quantity of water treatment by-products, concentration of airborne particulate matter and fresh air need to be controlled. The two
areas of principal concern for health are Legionella and disinfection by-products,
particularly chloramines. Although Legionella should primarily be controlled
in the water systems, areas housing natural spas (thermal water) and hot tubs
should also be well ventilated. Reducing exposure to disinfection by-products in
air should be pursued in order to minimize overall exposure to these chemicals,
as inhalation appears to be the dominant route of exposure during recreational
water use (see Chapter 4). As concentrations of disinfection by-products decrease rapidly with distance from the water, this has implications for ventilation
design, which involves both mixing and dilution (i.e. with fresh air), and building codes should stipulate appropriate ventilation rates (at least 10 litres of fresh
air/s/m2 of water surface area).
• Staff and user comfort. The temperature, humidity and velocity of the pool hall
air should be appropriate to provide a comfortable environment.
• Impact on the building fabric. The air temperature, concentration of airborne
particulate matter and quantity of water treatment by-products need to be controlled in order to avoid an ‘aggressive environment’ that may damage the building fabric.
CHAPTER 5.
layout Safe Water.indd 115
MANAGING WATER AND AIR QUALITY
93
24.2.2006 9:57:18
5.10 Monitoring
Parameters that are easy and inexpensive to measure reliably and of immediate operational health relevance (such as turbidity, residual disinfectant and pH) should
be monitored most frequently and in all pool types. Whether any other parameters
(physical, chemical and microbial) need to be monitored is, in practice, determined
by management capacity, intensity of use and local practice. However, microbial
monitoring is generally needed in public and semi-public pools.
There should be pre-established (clear, written) procedures set up by managers for
acting on the results of monitoring, including how to act on any unexpected results.
Operators must know what to do themselves or how to ensure that appropriate action
is taken by someone else. Management should review data and test systems regularly
and ensure that pool operators have taken appropriate remedial action.
5.10.1 Turbidity
Turbidity testing is simple; approaches to establishing appropriate, facility-specific
turbidity standards are described in Section 5.4.2. Exceedance of a turbidity standard suggests both a significant deterioration in water quality and a significant health
hazard. Such exceedance merits immediate investigation and should lead to facility
closure unless the turbidity can rapidly be brought within standards.
5.10.2 Residual disinfectant level
National or other standards for minimum and maximum levels of residual disinfectant vary widely. The main factor is that the residual disinfectant level should always
be consistent with satisfactory microbial quality.
Failure to maintain target residual disinfectant should result in immediate investigation and follow-up testing. If residuals cannot be rapidly re-established and
maintained, then full investigation of cause and prevention of repetition are merited,
and public health authorities should be consulted in determining whether the facility
should remain open.
1. Chlorine-based disinfectants
For a conventional public or semi-public swimming pool with good hydraulics and
filtration, operating within its design bathing load and turnover and providing frequent (or online) monitoring of chlorine and pH, experience has shown that adequate routine disinfection should be achieved with a free chlorine level of 1 mg/l
throughout the pool. Free chlorine levels well above 1.2 mg/l should not be necessary
anywhere in the pool unless the pool is not well designed or well operated – if, for
example, circulation is too slow, distribution is poor or bathing loads are too heavy;
where this is the case, it is more appropriate in the long term to deal with the underlying problem, rather than increasing disinfection levels.
Experience suggests that the combined chlorine level within pool water (chloramines)
should be no more than half the free chlorine level (but combined chlorine should be as
low as possible and ideally less than 0.2 mg/l). If the levels are high, then it is likely that
there is too much ammonia in the water, indicating that bathing loads or pollution from
bathers may be too high, that dilution is too low or that treatment is suboptimal.
Lower free chlorine concentrations (0.5 mg/l or less) will be adequate where
chlorine is used in conjunction with ozone or UV disinfection. Higher concentra94
layout Safe Water.indd 116
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:18
tions (up to 2–3 mg/l) may be required to ensure disinfection in hot tubs, because of
higher bathing loads and higher temperatures.
If the chlorine source is chlorinated isocyanurate compounds, then the level of
cyanuric acid must also be monitored and controlled; if it becomes too high (above
100 mg/l), microbial conditions may become unsatisfactory, and increased freshwater
dilution is required.
2. Bromine-based disinfectants
Total bromine levels in swimming pools, should ideally be maintained at 2.0–2.5 mg/l.
When bromine-based disinfectants are used in combination with ozone, the concentration of bromide ion should be monitored and maintained at 15–20 mg/l. If BCDMH
is the bromine source, the level of dimethylhydantoin must also be monitored; it should
not exceed 200 mg/l.
3. Sampling and analysis
In public and many semi-public pools, there will be continuous monitoring of residual
disinfectant levels as the disinfectant is dosed (see Section 5.3.4). In addition to this, samples should also be taken from the pool itself. In public and semi-public pools, residual
disinfectant concentrations should be checked by sampling the pool before it opens and
during the opening period (ideally during a period of high bathing load). The frequency
of testing while the swimming pool is in use depends upon the nature and use of the
pool. It is suggested that the residual disinfectant concentration in domestic pools be
checked before use. All tests must be carried out immediately after the sample is taken.
Samples should be taken at a depth of 5–30 cm. It is good practice to include as a
routine sampling point the area of the pool where, because of the hydraulics, the disinfectant residual is generally lowest. Occasional samples should be taken from other
parts of the pool and circulation system.
The tests employed should be capable of determining free chlorine and total bromine levels (depending upon the disinfectant used). Analysis is generally performed
with simple test kits based on the N,N-diethyl-p-phenylenediamine (DPD) method,
using either liquid or tablet reagents. This method can measure both free and total
disinfectant and is available as both colorimetric and titration test kits.
5.10.3 pH
The pH of swimming pool water should be controlled to ensure efficient disinfection
and coagulation, to avoid damage to the pool fabric and ensure user comfort. The
pH should be maintained between 7.2 and 7.8 for chlorine disinfectants and between
7.2 and 8.0 for bromine-based and other non-chlorine processes. The frequency of
measurement will depend upon the type of pool. It is suggested that for public pools,
the pH value should be measured continuously and adjusted automatically; for other
semi-public pools and public and semi-public hot tubs, it is suggested that monitoring be conducted several times a day, during operating hours; for domestic pools, it is
advisable to measure prior to pool use. Actions to be taken on failure to maintain pH
within the target range are similar to those for disinfectant residual.
CHAPTER 5.
layout Safe Water.indd 117
MANAGING WATER AND AIR QUALITY
95
24.2.2006 9:57:18
5.10.4 Oxidation–reduction potential (ORP)
The oxidation–reduction potential (also known as ORP or redox) can also be used
in the operational monitoring of disinfection efficacy. In general terms for swimming
pools and similar environments, levels in excess of 720 mV (measured using a silver/
silver chloride electrode) or 680 mV (using a calomel electrode) suggest that the water
is in good microbial condition, although it is suggested that appropriate values should
be determined on a case-by-case basis.
5.10.5 Microbial quality
There is limited risk of significant microbial contamination and illness in a well
managed pool with an adequate residual disinfectant concentration, a pH value
maintained at an appropriate level, well operated filters and frequent monitoring of
non-microbial parameters. Nevertheless, samples of pool water from public and semipublic pools should be monitored at appropriate intervals for microbial parameters.
Such tests do not guarantee microbial safety but serve to provide information with
which to judge the effectiveness of measures taken.
1. ‘Indicator’ organisms
As outlined in Chapter 3, monitoring for potential microbial hazards is generally
done using ‘indicator’ microorganisms, rather than specific microbial hazards (see
Box 3.1). Microorganisms used to assess the microbial quality of pools and similar
environments include heterotrophic plate count (HPC), thermotolerant coliforms,
E. coli, Pseudomonas aeruginosa, Legionella spp. and Staphylococcus aureus. Where
operational guidelines are exceeded, pool operators should check turbidity, residual
disinfectant levels and pH and then resample. When critical guidelines are exceeded,
the pool should be closed while investigation and remediation are conducted.
HPC
The HPC (37 °C for 24 h) gives an indication of the overall bacterial population within
the pool. This should be monitored in public and semi-public disinfected swimming
pools. It is recommended that operational levels should be less than 200 cfu/ml.
Thermotolerant coliforms and E. coli
Thermotolerant coliforms and E. coli are indicators of faecal contamination. Either
thermotolerant coliforms or E. coli should be measured in all public and semi-public
pools, hot tubs and natural spas. Operational levels should be less than 1/100 ml.
Pseudomonas aeruginosa
Routine monitoring of Pseudomonas aeruginosa is recommended for public and semipublic hot tubs and natural spas. It is suggested for public and semi-public swimming
pools when there is evidence of operational problems (such as failure of disinfection
or problems relating to filters or water pipes), a deterioration in the quality of the pool
water or known health problems. It is recommended that for continuously disinfected
pools, operational levels should be <1/100 ml; where natural spas operate with no
residual disinfectant, operational levels should be <10/100 ml.
If high counts are found (>100/100 ml), pool operators should check turbidity,
disinfectant residuals and pH, resample, backwash thoroughly, wait one turnover
and resample. If high levels of P. aeruginosa remain, the pool should be closed and a
96
layout Safe Water.indd 118
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:19
thorough cleaning and disinfection programme initiated. Hot tubs should be shut
down, drained, cleaned and refilled.
Legionella spp.
Periodic testing for Legionella is useful, especially from hot tubs, in order to determine
that filters are not being colonized, and it is recommended that operational levels
should be <1/100 ml. Where this is exceeded, hot tubs should be shut down, drained,
cleaned and refilled. Shock chlorination may be appropriate if it is suspected that
filters have become colonized.
Staphylococcus aureus
The routine monitoring of Staphylococcus aureus is not recommended, although monitoring may be undertaken as part of a wider investigation into the quality of the
water when health problems associated with the pool are suspected. Where samples
are taken, levels should be less than 100/100 ml.
2. Sampling
Guidelines on routine sampling frequencies, along with a summary of operational
guideline values, are outlined in Table 5.3. In addition to routine sampling, samples
should also be taken from public and semi-public facilities:
•
•
•
•
before a pool is used for the first time;
before it is put back into use, after it has been shut down for repairs or cleaning;
if there are difficulties with the treatment system; and
as part of any investigation into possible adverse effects on bathers’ health.
Table 5.3. Recommended routine sampling frequenciesa and operational guidelinesb for microbial testing during normal operation
Heterotrophic
plate count
Thermotolerant
coliform/E. coli
Pseudomonas
aeruginosa
Legionella
spp.
Disinfected pools,
public and heavily
used
Weekly
(<200/ml)
Weekly
(<1/100 ml)
When situation
demandsc
(<1/100 ml)
Quarterly
(<1/100 ml)
Disinfected pools,
semi-public
Monthly
(<200/ml)
Monthly
(<1/100 ml)
When situation
demandsc
(<1/100 ml)
Quarterly
(<1/100 ml)
Natural spas
n/a
Weekly
(<1/100 ml)
Weekly
(<10/100 ml)
Monthly
(<1/100 ml)
Hot tubs
n/a
Weekly
(<1/100 ml)
Weekly
(<1/100 ml)
Monthly
(<1/100 ml)
Pool type
a
Samples should be taken when the pool is heavily loaded
Sampling frequency should be increased if operational parameters (e.g. turbidity, pH, residual disinfectant concentration) are not maintained within target ranges
Sample numbers should be determined on the basis of pool size and complexity and should include point(s) representative of general
water quality and likely problem areas
b
Operational guidelines are shown in parentheses
c
e.g. when health problems associated with the pool are suspected
CHAPTER 5.
layout Safe Water.indd 119
MANAGING WATER AND AIR QUALITY
97
24.2.2006 9:57:20
The most appropriate site for taking a single sample is where the water velocity
is low, away from any inlets. Depending on the size of the pool, it may be advisable
to take samples from multiple sites. Many leisure pools will have additional features,
such as flumes, islands and backwaters with a complex system of water flow; representative samples should be taken.
Misleading information on pool water quality will result from incorrect sampling
procedures. Sample containers must be of a material that will not affect the quality of
the sample either microbially or chemically. Although a good-quality glass container
will meet these requirements, the risk of broken glass in the pool environment as a
result of breakage has favoured the use of shatterproof plastic-coated glass containers.
All-plastic containers can be used provided they do not react with microorganisms or
chemicals in the water; not all are suitable.
For microbial examination, the bottle must be sterile and contain an agent that
neutralizes the disinfectant used in the pool water. Sodium thiosulfate (18–20 mg/l)
is the agent used for chlorine- and bromine-based disinfectants. Clearly, the testing
laboratory must be advised before sampling if any other disinfectant is being used.
Bacteria in pool water samples and especially those from disinfected pools may be
‘injured’, and normal analytical ‘resuscitation’ procedures should be fully adhered to.
5.10.6 Other operational parameters
Several parameters are important for operational purposes. These include:
• alkalinity: Alkalinity is a measure of the alkaline salts dissolved in the water. The
higher the alkalinity, the more resistant the water is to large changes in pH in
response to changes in the dosage of disinfectant and pH correction chemicals.
If the alkalinity is too high, it can make pH adjustment difficult.
• calcium hardness: Calcium hardness is an operational measure that needs to be
monitored to avoid damage to the pool fabric (e.g. etching of surfaces and metal
corrosion) and scaling water.
• total dissolved solids: Total dissolved solids (TDS) is the weight of soluble material in water. Disinfectants and other pool chemicals as well as bather pollution
will increase TDS levels. The real value of detecting an increase in TDS levels is
as a warning of overloading or lack of dilution, and TDS levels should be monitored by comparison between pool and source water. If TDS is high, dilution is
likely to be the correct management action.
5.11 Cleaning
Good water and air quality cannot be maintained without an adequate cleaning programme. This should include the toilets, showers, changing facilities and pool surroundings on at least a daily basis in public and semi-public pools. Public and semi-public
hot tubs should be drained and the surfaces and pipework cleaned on a weekly basis.
Heating, ventilation and air-conditioning systems should be cleaned periodically (e.g.
weekly to monthly for those serving hot tubs). Features such as water sprays should be
periodically cleaned and flushed with disinfectant (e.g. 5 mg/l hypochlorite solution).
98
layout Safe Water.indd 120
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:21
5.12 References
BSI (2003) Management of public swimming pools – water treatment systems, water treatment plant and heating and ventilation systems – code of practice. British Standards Institute, Publicly Available Specification
(PAS) 39: 2003.
Eichelsdörfer D (1987) [Investigations of anthropogenic load of swimming pool and bathing water.] A.B.
Archiv des Badewesens, 40: 259–263 (in German).
Eichelsdörfer D, Jandik J (1979) [Ozone as oxidizer.] A.B. Archiv des Badewesens, 37: 257–261 (in German).
Eichelsdörfer D, Jandik J (1984) [Investigation and development of swimming pool water treatment. III.
Note: Pool water treatment with ozone in long time contact.] Zeitschrift für Wasser- und Abwasser Forschung,
17: 148–153 (in German).
Eichelsdörfer D, Jandik J, Weil
(1981) [Formation and occurrence of organic halocarbons in swimming pool water.] A.B. Archiv des
Badewesens, 34: 167–172 (in German).
Gansloser G, Hässelbarth U, Roeske W (1999) [Treatment of swimming pool and bathing water.] Berlin,
Beuth Verlag (in German).
Gregory R (2002) Bench-marking pool water treatment for coping with Cryptosporidium. Journal of Environmental Health Research, 1(1): 11–18.
ISO (1999) Water quality – Determination of turbidity. Geneva, International Organization for Standardization (ISO 7027:1999).
Locher A (1996) [Non-chlorine treatment of pool water.] Gesundheits- und Umwelttechnik, 3: 18–19 (in
German).
MDHSS (undated) Swimming pool and spa water chemistry. Missouri Department of Health and Senior
Services, Section for Environmental Health (http://www.health.state.mo.us/RecreationalWater/Pool
SpaChem.pdf ).
Rice RG (1995) Chemistries of ozone for municipal pool and spa water treatment. Journal of the Swimming
Pool and Spa Industry, 1(1): 25–44.
Saunus C (1998) [Planning of swimming pools.] Düsseldorf, Krammer Verlag (in German).
CHAPTER 5.
layout Safe Water.indd 121
MANAGING WATER AND AIR QUALITY
99
24.2.2006 9:57:22
CHAPTER 6
Guideline implementation
R
ecreational water activities can bring health benefits to users, including exercise
and relaxation. However, negative health effects may also arise as described in previous chapters. It is necessary to address these issues and implement effective management options in order to minimize the adverse health consequences through implementation of the Guidelines.
Different stakeholders play different roles in the management of the recreational
water environment for safety. The typical areas of responsibility may be grouped into
four major categories, although there may be overlap between these and stakeholders
with responsibilities falling within more than one category:
•
•
•
•
design and construction;
operation and management;
public education and information; and
regulatory requirements (including compliance).
This chapter is arranged according to these categories, with the main stakeholders
indicated for each category. Successful implementation of the Guidelines will require
development of suitable capacities and expertise and the elaboration of a coherent
policy and legislative framework.
6.1 Design and construction
People responsible for commissioning pools and similar environments, along with
designers and contractors, should be aware of the requirements to ensure safe and
enjoyable use of facilities. Many decisions taken at the design and construction stage
will have repercussions on the ease with which safe operation can be ensured once the
pool is in use.
Table 6.1 summarizes examples of good practice in design, specification or construction of swimming pools and similar environments in relation to the major health
issues discussed in previous chapters, while Table 6.2 examines specific risks in various
pool types in relation to design and construction issues.
Local and national authorities may set specific requirements that must be met in
the design and construction of swimming pools and similar recreational water facilities (see also Section 6.4). Alternatively, less formal guidelines may be established by
these authorities or by professional or trade associations. Competent and experienced
persons may be members of professional associations or may be subject to licensing
schemes in order to practise (see Section 6.4.2). There may be a process of approval for design and during construction – for example, through building regulations.
100
layout Safe Water.indd 122
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:23
Table 6.1. Examples of good practice in design and construction: major health-related issues
Objectivea
Prevention of
entrapment injuries (2)
Prevention of
diving accidents (2)
Enable adequate
lifeguarding (2)
Prevention of
slip/trip/fall
accidents (2)
Typical actions/requirements of good practice
Specify minimum two suction drains per pump system, with drains
sufficiently separated to prevent trapping.
Properly installed outlets and drain grates to prevent suction entrapment.
Pump shut-off permanently accessible to lifeguards or public (if no permanent lifeguard).
Clear indication of depth in locally comprehensible manner at frequent
intervals.
All areas of pool visible from lifeguarding posts.
Adequate artificial light.
Glare does not impede underwater visibility.
Plain pool bottom assists recognition of bodies.
Non-slip surround surfaces.
Area bordering pool clear of tripping hazards (e.g. pipes and equipment).
Temporary fixtures create no hazard when removed (e.g. starting blocks).
Pool surround sloped to drain effectively.
Edge of pool surround in contrasting colour (unless gentle slope from
surface).
Steps, treads, etc. marked by contrasting colour.
Pool and surround free of sharp edges or projections.
Minimize unintentional
immersion and enable
self-recovery
(especially for
non-swimmers) (2)
Avoid unauthorized access, isolation fencing (enclosing the pool only)
at least 1.2 m high with self-closing, self-latching gate is recommended
for pools where children could obtain unsupervised access.
Avoid abrupt changes in depth, especially in shallow (e.g. <1.5 m depth)
waters.
Changes in depth identified by use of colour-contrasted materials.
Side and end walls vertical for a minimum of 1 m.
Steps/ladders for easy access in and out of pool.
Minimize and control
faecal and non-faecal
microbial
contamination (3)
Provide easy access to toilets and showers.
Design pre-swim showers so bathers have to shower before entrance to the
pool area.
Strategic placement of footbaths.
Provision of adequate treatment capacity.
On commissioning or after equipment change or modification to pipes,
drains, etc., confirm circulation pattern and absence of ‘dead spots’ (e.g.
by dye tests).
For public and semi-public pools (where possible), include small, separate
pools for children to facilitate draining in response to accidental faecal
releases.
Minimize exposure to
volatile chemicals (4)
Minimize formation of
disinfection by-products
by control of precursor
input (5)
Ensure air flow across water surface (forced or natural ventilation) and
adequate fresh air exchange.
Design pool treatment system to reduce DBP formation (e.g. water pretreatment if necessary, disinfection systems that use less chlorine – e.g.
UV or ozone plus chlorine).
Provide easy-access toilets and showers.
a
Relevant chapter references are identified in parentheses
CHAPTER 6.
layout Safe Water.indd 123
GUIDELINE IMPLEMENTATION
101
24.2.2006 9:57:23
Table 6.2. Health risks and design and construction issues associated with various pool types
Pool type or use
(refer to Chapter 1) Special risk factorsa
Natural spa waters
Inability of users to see changes of
(coloured or turbid) depth (2)
Inability of lifeguards to see bodies
under surface (2)
Flow-through seawater Polluted water in harbour areas
Injuries during ship movement in heavy
swimming pools on
cruise ships and ferries seas
Open-air pools
Unauthorized access to children (2)
(e.g. when the pool is closed or unsupervised)
Principal requirement/action
No sudden underwater depth changes
or steps
Refer to WHO Guide to Ship Sanitation
(in preparation)
Exclusion of unsupervised children
through fencing, walls with childproof gates/doors
Algal growth (5)
Best controlled by good hydraulic
design
Contamination by mud and grass on
users’ feet (5)
Provision of pre-swim showers and
footbaths
Contamination by animal faeces, animal Exclusion of animals
urine and wind-blown matter (3 and 5) Edge drainage draining away from
the pool
Ensuring adequate treatment capacity and good circulation and hydraulic design
Semi-public pools
Domestic pools (including temporary
and portable pools)
Hot tubs
Lack of adequate water quality manage- Water quality best controlled by
ment increases the risk of illness (3)
ensuring appropriate treatment
capacity, the inclusion of automatic
monitoring and chemical dosing
systems and good circulation and
hydraulic design
Unauthorized access to children (2)
Provision of isolation fencing with
(i.e. when the pool is unsupervised)
child-proof gates
Unauthorized access to children (2)
Provision of lockable safety covers
(i.e. when the hot tub is unsupervised) on domestic and outdoor hot tubs
Difficulty in maintaining an appropriate Provide identifiable seats to prevent
overcrowding. Facility designed to
residual disinfectant level (3 and 4)
enable ‘rest periods’ to be programmed, to discourage excessive
use and allow disinfectant levels to
‘recover’
Temperature too hot
a
Pre-set maximum temperature <40 °C
Relevant chapter references are identified in parentheses
102
layout Safe Water.indd 124
24.2.2006 9:57:24
Equipment specified or purchased should meet prevailing standards (see Section
6.4.2). In addition, guidance may be available with regards to the most suitable materials to use for construction to minimize problems with corrosion.
6.2 Operation and management
Facility operators play a key role and are responsible for the good operation and management of the recreational water environment. Good operation is vital to minimize
possible negative health impacts. Table 6.3 summarizes examples of good practice in
operation and management to deal with the hazards identified in previous chapters.
Table 6.4 examines specific risks in relation to good operation and management
by pool type.
6.2.1 Pool safety plan
The facility operator should have a pool safety plan, which consists of a description
of the system, its monitoring and maintenance, normal operating procedures, a set
of procedures for specified incidents, an emergency evacuation procedure and a generic emergency plan (for things not covered under the specified incidents). Examples
of what should be included within the normal operating procedure are outlined in
Box 6.1.
BOX 6.1 EXAMPLES OF NORMAL OPERATING PROCEDURES
1. Details of the pool(s); this should include dimensions and depths, features and equipment and a
plan of the whole facility. The plan should include positions of pool alarms, fire alarms, emergency
exit routes and any other relevant information.
2. Potential risk; a description of the main hazards and user groups particularly at risk is required
before safe operating procedures can be identified.
3. Dealing with the public; arrangements for communicating safety messages to customers, ensuring
maximum bather numbers are not exceeded, customer care and poolside rules.
4. Lifeguard’s duties and responsibilities (see Section 6.2.2), including special supervision requirements for equipment, etc., lifeguard training and numbers of lifeguards for particular activities.
5. Systems of work, including lines of supervision, call-out procedures, work rotation and maximum
poolside working times.
6. Controlling access to a pool or pools intended to be out of use, including the safe use of pool covers.
7. Water quality monitoring, including how often, how and where samples are to be taken, details of
the operational and critical limits and actions to be taken if water quality is not satisfactory.
8. Response to an accidental faecal release (or this may be covered under an incident plan).
9. Detailed work instructions, including pool cleaning procedures, safe setting up and checking of
equipment and setting up the pool for galas.
10. First-aid supplies and training, including equipment required, its location, arrangements for checking it, first aiders, first-aid training and disposal of sharp objects.
11. Details of alarm systems and any emergency equipment, maintenance arrangements; all alarm
systems and emergency equipment provided, including operation, location, action to be taken on
hearing the alarm, testing arrangements and maintenance.
12. Conditions of hire to, or use by, outside organizations.
Adapted from Sport England & Health and Safety Commission, 2003
CHAPTER 6.
layout Safe Water.indd 125
GUIDELINE IMPLEMENTATION
103
24.2.2006 9:57:25
Table 6.3. Good practice in operation and management: major health-related issues
Objectivea
Prevention of
drowning
incidents (2)
Typical actions/requirements of good practice
Provision of properly trained and equipped lifeguards.
Declared procedure for dealing with emergencies, all staff trained and familiar.
Water turbidity monitored and action plan in place to deal with trends or deviations from acceptable range.
Natural spas and hot tubs operated at temperatures below 40 °C.
Ensuring unauthorized access is prevented.
Installation and maintenance of appropriate water safety signage.b
Forbidding consumption or sale of alcohol at recreational facility.
Prevention of
Signageb against diving into shallower water, active lifeguard supervision and
diving injuries (2) intervention supported by management.
Starting blocks and diving boards inaccessible to untrained persons.
High boards with non-slip surfaces and side rails.
Where possible (larger pools), designated areas for non-swimmers and children,
increased supervision.
Prevention of enChecking that drain covers are in place and undamaged.
trapment injuries (2) Emergency shut-off is clearly marked.
Prevention of
Regular cleaning programme for all surfaces subject to algal or bacterial growth.
slip/trip/fall
Minimize presence of moveable objects (i.e. objects that could be transported
accidents (2)
near to pool edge and constitute a trip hazard).
Accident response Written emergency evacuation procedure and generic emergency plan.
capability (2)
Rescue and resuscitation equipment available to lifeguards.
First-aid equipment readily available.
Communication links to local emergency and first-aid facilities readily available.
Control after
Declared procedure for dealing with accidental faecal releases, all staff trained
accidental faecal
and familiar. For example:
releases (3 and 5) • Evacuation of pool immediately after accidental faecal releases.
• Pool maintained out of use for a specified period, six full turnovers of
filtration cycle during which disinfectant concentrations to be elevated and
maintained at maximum normal operating concentration.
• Total drain-down and cleaning of children’s pools.
Maintenance of
water quality and
clean ancillary
facilities (3 and 5)
Encouraging users to shower before using the facilities (e.g. through the use of
posters and educational material – see also Section 6.3).
Stated water quality and facilities monitoring programme implemented and
recorded by trained staff.
Respect bathing load limits.
Declared process for dealing with adverse trends and unacceptable values.
Previous identification of source of expertise/reference in case of problems.
Availability of critical parameter water-testing equipment.
Filtration performance periodically monitored and action taken if outside
operational requirements.
Maintenance of toilets, showers and changing rooms in clean, socially
acceptable state.
Maintenance
of air quality (5)
Manage DBP formation by encouraging users to shower before using the facilities.
Monitoring.
Ensuring adequate ventilation, especially across the pool surface, and suitable
exchange with fresh air.
a
Chapter
b
references are given in parentheses
Signage is also an education issue and is covered in more detail in Section 6.3.1
104
layout Safe Water.indd 126
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:25
The normal operating procedures cover day-to-day management and aim to
prevent problems such as poor air and water quality or overcrowding from arising,
through monitoring and appropriate management actions. In terms of water quality
monitoring, for a number of parameters there will be both operational and critical
limits (see Section 5.10). When operational limits are exceeded, action should be
taken to bring levels back in line with guidelines or standards. When a critical limit is
exceeded, more urgent action is required, which may include closing the facility.
In addition to normal operating procedures, it is also necessary to have a series
of incident plans that cover less routine matters, such as an accident to a water slide
user (see Box 6.2) or how to manage an accidental faecal release (if this is not covered
under the normal operating procedure – see Section 5.8).
Situations that are not covered by either the normal operating procedure or the
incident plans are likely to be unanticipated emergency situations such as structural
failure and should be dealt with according to an emergency evacuation procedure.
The pool safety plan should be fully documented and the results of monitoring and
any incidents recorded.
6.2.2 Lifeguards
The primary responsibilities of the lifeguard include the following (Sport England &
Health and Safety Commission, 2003):
• supervising the pool area, keeping a close watch over the pool and its users;
• preventing injuries by minimizing or eliminating hazardous situations, intervening to prevent unsafe behaviours, exercising appropriate control and enforcing all facility rules and regulations;
• anticipating problems and preventing accidents, including warning bathers of
the risks of their specific behaviours;
• identifying emergencies quickly and responding effectively, including effecting
a rescue from the water, administering first aid or CPR, and informing other
lifeguards and facility staff when more help or equipment is needed; and
• communicating with the pool users and colleagues.
Secondary responsibilities should not interfere with the primary responsibilities of
lifeguard personnel. These secondary responsibilities include informing patrons about
rules and regulations, helping patrons locate a missing person, completing required
records and reports on schedule and submitting them to the proper person or office,
and undertaking maintenance or other tasks as assigned.
A detailed example of the duties and requirements of a lifeguard and determination of lifeguard staffing levels are outlined in Appendix 1.
6.3 Public education and information
Facility operators, local authorities, public health bodies, pool-based clubs (such as
swimming clubs, aqua-aerobics classes, scuba clubs and so on) and sports bodies can
play an important role in ensuring pool safety through public education and providing appropriate and targeted information to pool users. Table 6.5 outlines education
requirements and responses to identified risks by pool type.
CHAPTER 6.
layout Safe Water.indd 127
GUIDELINE IMPLEMENTATION
105
24.2.2006 9:57:26
Table 6.4. Health risks and operation and management actions associated with various pool types
Pool type or use
(refer to Chapter 1) Special risk factorsa
Principal requirement/action
Natural spa and
thermal waters
High water temperatures (2)
Microbial water quality if water
is untreatable (problems may be
encountered with filtration and/or
disinfection) (3)
Limit temperatures to below 40 °C.
Drain-down obligatory after accidental
faecal release. Monitoring for faecal indicators required. Special water
quality management regime typically
requires, for example, physical cleaning of surfaces above and below water.
Regular drain-down and a high rate of
dilution to waste.
Flumes, wave
machines, etc.
Increased accident hazards, inhibition of visibility (2)
More intensive supervision.
Avoid overcrowding
Pre-warning of change in water conditions.
Flow-through
seawater swimming
pools on cruise
ships and ferries
Risk of contamination from sewage
discharge in source water
Injuries during ship movement in
high seas
Open-air pools
Maintenance of fencing, walls with
Unauthorized access to children
(2) (e.g. when the pool is closed or child-proof gates/doors.
unsupervised)
Refer to WHO Guide to Ship Sanitation
(in preparation)
Exposure to UV radiation degrades
residual disin fectant (5)
Close monitoring of residual disinfectant
or use of stabilizer (e.g. chlorinated
isocyanurates) to lessen degradation.
Algal growth (5)
Ensuring effective disinfection and good
hydraulic design. If problems persist,
then proprietary algicides for swimming
pool application may be used.
Contamination by mud and grass on Encouragement of the use of pre-swim
showers and footbaths. Cleaning and
users’ feet (5)
maintenance around the pool area.
Contamination by animal faeces,
animal urine and wind-blown
matter (3 and 5)
Public and semi-pub- Increased inappropriate behaviour,
lic pools with access reduced ability to cope, impaired
to alcohol
judgement (2)
Banning of pets. Removal of litter to discourage presence of animals. Cleaning.
Ensuring effective disinfection and
filtration as well as good water circulation.
Recommendations that facilities are
not used while under the influence of
alcohol.
Supervision required.
Physical exclusion of access at unsupervised times.
106
layout Safe Water.indd 128
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:26
Table 6.4. (continued)
Pool type or use
(refer to Chapter 1) Special risk factorsa
Principal requirement/action
Maintenance of isolation fencing with
Domestic pools
Unauthorized access to children
(including temporary (2) (e.g. when the pool is unsuper- child-proof gates.
and portable pools) vised)
Monitor water quality.
Drain pool (if small), wash and refill
Deterioration in water quality (3)
after an accidental faecal release.
Hot tubs
Unauthorized access to children (2) Securing of safety covers on domestic
(e.g. when the hot tub is unsuper- and outdoor tubs.
vised)
Aerosolization (3)
Limit temperature to below 40 °C.
Legionella-specific management (see
Section 3.4.1).
Difficulties in maintaining disinfec- Increased disinfectant monitoring.
Implementation of ‘rest periods’ durtant residual (5)
ing use to allow disinfectant levels to
‘recover’.
a
Relevant chapter references are identified in parentheses
BOX 6.2 EXAMPLE INCIDENT PLAN FOR LIFEGUARDS MONITORING A WAVE POOL OR WATER SLIDE
When you spot a user who needs help, follow this procedure:
• By immediately blowing one long, loud whistle blast, you notify your safety team that there is an
incident. Once you have given the signal, members of the safety team can react to the situation.
• Stop the waves or slide dispatch. At a wave pool, hit the emergency stop button to be sure the
waves are turned off. If you are on duty at the top of an attraction, do not dispatch any more riders.
Communication between the top and bottom positions is vital.
• Determine which method of rescue is needed. If it is necessary to enter the water to make a rescue,
use the entry most appropriate for the location you are lifeguarding. For example, you might use a
compact jump from a head wall. If it isn’t necessary to enter the water, use the appropriate equipment to help the victim.
• If you are not the lifeguard making the rescue, make sure the rescuing lifeguard’s observation zone
is covered.
• Once the situation is under control, the lifeguard who made the rescue completes and files an incident report as soon as time permits. This report form should have a diagram of the pool or activity
on the back so that the location of the incident can be marked for future study.
• All equipment used in the rescue must be checked to ensure it remains in good condition and is
returned to the appropriate location. Lifeguards return to duty, if able, and users are allowed to
participate in the activity again if there are enough guards to cover it.
CHAPTER 6.
layout Safe Water.indd 129
GUIDELINE IMPLEMENTATION
107
24.2.2006 9:57:26
Incident plan flowchart
Lifeguard Recognizes Emergency and Acts
Other Lifeguards Provide Backup and Coverage
Contacts Victim and Moves to Safety
Assesses Victim’s Condition
Victim is OK
Victim Needs Care
Complete Report
Other Lifeguard Assists
Equipment Checked and Replaced
First Aid Provided
Any Corrective Action Taken
Emergency Medical Services Notified
by Team Member
Return to Duty
Pool Cleared by Backup Lifeguard, if Necessary
Staff Discussion
Supervisor Notified
Witnesses Interviewed
Report Completed
Equipment Checked and Replaced
Any Corrective Action Taken
Return to Duty
Staff Discussion
Adapted from American Red Cross, 1995
6.3.1 Signage
Information can be conveyed by means of prominently and appropriately located
signs. These should provide concise information and a single message (as distinct
from notices and posters, which are covered under Section 6.3.2). Signs can be used
to inform people of hazards and safe behaviours and also reinforce previous educational messages. Warning signs, in particular, should be simple to understand and
display a clear message. Many national organizations have adopted descriptive standards for warning and information signs, and the International Organization for
108
layout Safe Water.indd 130
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:26
Table 6.5. Education to reduce health risks from special risk factors
Pool type or use
(refer to Chapter 1)
Natural spa waters
Special risk factorsa
Microbial water quality if
water is untreatable (3)
Management action
Education for high-risk users on infection
risk
Unauthorized access to children (2) (e.g. when pool is
unsupervised or closed)
Education of children and parents/caregivers on the drowning hazard posed by
pools
Water and air quality (5)
Education on the importance of pre-swim
hygiene
Public and semi-public
pools with access to
alcohol
Increased inappropriate
behaviour, reduced ability to
cope, impaired judgement (2)
Information regarding peer supervision
and safe behaviours, impact of alcohol
Domestic pools
(including temporary
and portable pools)
Unauthorized access to
children (2)
Education of children and parents/caregivers on the drowning hazard posed by
pools and hot tubs
Hot tubs
Aerosolization (3)
Difficulties in maintaining
residual disinfectant (5)
Education for high-risk users (such as
young, elderly, pregnant women and immunocompromised) on infection risk and
importance of avoiding excessive use
Overheating (2)
Alcohol warnings
Open-air pools
a
Relevant chapter references are identified in parentheses
Standardization (ISO) has adopted a standard for safety signs (not specifically swimming pool related) to try to avoid a proliferation of symbols that could cause confusion rather than send a clear message (ISO, 2003).
Signage can convey the need for awareness (e.g. danger), the hazard (e.g. shallow
water), the health risk (e.g. paralysis may occur) or the prohibition (e.g. no diving, no
running, no glass, no alcohol). Signage also includes pool labels and markings, such
as pool depth markings. Extra attention may be required when designing signs applicable to tourist groups with different languages and cultures, as, unsurprisingly, some
signs have been ineffective when such explanatory and precautionary information was
in a language not understood by the pool users.
Signs alone may have a limited impact on behaviour (Hill, 1984; Goldhaber &
de Turck, 1988). However, studies have shown that the public accept and recognize
warning placards, pictographs and labelling. Therefore, signs are best deployed to
reinforce previous awareness raising and education.
6.3.2 Education
Education can encourage pool, hot tub and natural spa users to adopt safer behaviours
that benefit both themselves and other users and should encompass issues such as preswim hygiene, when not to use a pool or similar environment and how to identify possible
hazards. Schools, public health bodies (including health care providers), facility operators
CHAPTER 6.
layout Safe Water.indd 131
GUIDELINE IMPLEMENTATION
109
24.2.2006 9:57:27
and user groups can all provide information. Castor & Beach (2004), for example, suggest that health care providers can help to disseminate healthy swimming messages to
their patients, especially those patients with diarrhoea and parents of children who are not
toilet trained, or patients who are particularly susceptible to certain diseases or conditions.
This would include messages on not swimming when you are suffering from diarrhoea,
on showering before swimming or that immunocompromised patients should take extra
precautions or not swim in areas with a higher probability of being contaminated.
Bather safety may be improved if possible hazards are clearly identified at the facility (see Section 6.3.1) and users educated before they enter the pool environment. An
attempt at education may also be made by handing safety leaflets to users at the pool
entrance or to those in charge of organized group activities and displaying posters
in reception and changing room areas (Sport England & Health and Safety Commission, 2003). Lifeguards can also act as information providers, although this role
should not interfere with their supervisory role.
Box 6.3 provides a code for pool users, which could be displayed in public areas or,
where membership to a facility is required, form part of a membership pack. Educational information can also be added to agreements or contracts with groups that use
pools for special purposes (e.g. scuba lessons, water aerobics, etc.).
BOX 6.3 EXAMPLE CODE FOR POOL USERS
Spot the dangers. Take care, swimming pools can be hazardous. Water presents a risk of drowning,
and injuries can occur from hitting the hard surrounds or from misuse of the equipment. Every pool is
different, so always make sure you know how deep the water is and check for other hazards, such as
diving boards, wave machines, water slides, steep slopes into deeper water, etc.
Always swim within your ability. Never swim under the influence of alcohol. Avoid holding your
breath and swimming long distances under water. Be especially careful if you have a medical condition such as epilepsy, asthma, diabetes or a heart problem. Follow advice provided for the safety of
yourself and others. Avoid unruly behaviour that can be dangerous, for instance, running on the side
of the pool, ducking, acrobatics in the water, or shouting or screaming (which could distract attention from an emergency). Always do as the lifeguards say, and remember that a moment of foolish
behaviour could cost a life.
Look out for yourself and other swimmers. It is safer to swim with a companion. Keep an eye open
for others, particularly younger children and non-swimmers. Learn how to help. If you see somebody
in difficulty, call for help immediately. In an emergency, keep calm and do exactly as you are told.
Do not swim if you have a gastrointestinal (stomach) upset or skin or respiratory infection. You
are likely to pass on the germs that are making you ill.
Shower before you swim. This will reduce the amount of germs, sweat and chemicals (such as cosmetics) that you transfer to the water. This means that the water quality of the pool will be better.
Adapted from Sport England & Health and Safety Commission, 2003
6.4 Regulatory requirements
National legislation may include different sets of regulations that will apply to swimming
pools and similar recreational environments. Regulation may control, for example, the
design and construction of pools (see Section 6.1), their operation and management (see
110
layout Safe Water.indd 132
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:27
Section 6.2) and substances hazardous to health (e.g. chemicals). These may be quite
detailed and specific in their requirements, covering water treatment processes, sampling
and testing regimes, and they may be applied differently according to the type of pool
(i.e. public versus semi-public versus domestic). Within regulations it is likely that there
will be a requirement for the use of certified material, equipment and, possibly, staff
registered to certain bodies (e.g. lifeguards, design and construction engineers).
Another aspect of pool management that may necessitate regulatory involvement
is occupational health and safety legislation, designed to ensure protection of pool
employees (occupational health is not covered by these Guidelines; see Chapter 1), as
well as the general public.
Local regulatory oversight can support the work of pool management and provide greater public health protection and public confidence. Inspections by the regulatory officials to
verify compliance with the regulations are an important component of this oversight.
6.4.1 Regulations and compliance
The extent to which swimming pools and similar environments are regulated varies greatly. In some countries, a permit or licence to operate is required by the local
municipal authority. In others, a level of regulatory oversight is provided, based on
specific regulations and/or advisory codes of practice.
Local authorities may, for example, require that the initial plans for the construction
of a new pool be submitted by a licensed engineer. The design and construction plans
are then reviewed and approved by a competent person. These plans generally include
complete details and layout of the facility, including amenities, and information regarding the individual circulation system components (pumps, filters, chemical dosing
system, etc.). Once approved, the construction of the facility may commence. However,
prior to issuance of the final permit for operation, a physical inspection of the final
facility and a review of the pool safety plan or daily operations management are usually
required. Periodic audits may be required to ensure continued compliance. Regulations should provide for authority to close the facility if serious hazards and breaches to
regulations or a significant risk to public health is identified, with reopening prohibited
until the problem has been rectified and measures are in place to prevent recurrence.
Most regulations apply to public pools, but limited evidence suggests that the
greatest burden of disease and physical injury arises from domestic and semi-public
pools. These may be subject to periodic or informal supervision, and their operation
and maintenance may be less adequate than those at public pools per se.
In terms of the operation and management of pools and similar environments, the
typical requirements, in terms of a normal operating procedure, incident plans and an
emergency plan, have already been outlined (Section 6.2). The preparation and use
of such procedures ensure that the hazards specific to that facility have been evaluated
and management actions determined.
It may be a regulatory requirement that the results of hygiene and safety monitoring be made available to the public; this may be useful in terms of public education
material and, if the regulator also provides comparable information from other venues, as a means of comparing the health and safety records of different facilities.
In all cases, regulatory involvement should be welcomed and not seen as a burden
on pool management. The purpose of regulatory involvement is to ensure that pools
and similar environments are operated as safely as possible in order that the largest
CHAPTER 6.
layout Safe Water.indd 133
GUIDELINE IMPLEMENTATION
111
24.2.2006 9:57:27
possible population gets the maximum possible benefit, not to close facilities or hinder their proper operation.
6.4.2 Registration and certification schemes
Certain staff members (e.g. lifeguards) and personnel involved in the design and construction (for example) may be required to be registered with certain approved bodies.
In addition, all equipment components installed in the facility should meet minimum
performance, design, sanitation and safety requirements. Certification that the equipment or the entire pool is in compliance with the guidelines or regulatory requirements is helpful for all involved parties. There are four basic methods of certification
in use; these are outlined in Box 6.4.
Equipment that may be certified for performance, sanitation and/or safety considerations includes the following: piping system; filters; pumps; surface skimmers; suction
fittings and drain covers; valves (multiport, three-way, butterfly, etc.); chemical feeding devices (mechanical, flow-through); process equipment (chlorine/bromine generators, ozone
generators, UV disinfection systems and copper/silver ion generators); heaters; automated
chemical monitor/controllers; chemical disinfectants; and electrical equipment (safety).
BOX 6.4 BASIC METHODS OF CERTIFICATION
• First party – Self-certification of the product’s compliance against a standard by the manufacturer.
Concerns are often raised with manufacturers’ self-certification because of the potential bias of the
manufacturer and the lack of ongoing monitoring to ensure that the product continues to comply.
• Second party – Certification by a trade association or private party. In many instances, trade associations or private companies provide testing and certification services for products against
industry standards or regulations. Since a trade association represents and is often controlled by
manufacturers, second-party certifications are not considered to be completely independent. Typically, no follow-up services to monitor continued compliance are provided. As a result, it is often
difficult to determine whether a product selected for use is identical to the unit that was originally
evaluated for certification. Private entities also offer testing and certification services that monitor the continued compliance of the product. These follow-up services often include audits of the
production location, ongoing testing and complaint investigation.
• Third party – Certification by an independent organization without direct ties to the manufacturing sector. Third-party certifications provide for an independent evaluation of the product coupled
with follow-up services that help ensure that products continue to comply with all requirements.
These follow-up services typically include audits of the production location, ongoing testing of
representative products and complaint investigation. The follow-up service aspect of third-party
certification is an advantage, in that the purchaser has the assurance that the product installed is
identical to the product evaluated for the certification. Third-party certifiers also maintain close
working relationships with the regulatory and user communities. This provides for a more balanced
assessment of the product and helps ensure that the product will be accepted by local, regional and
national regulatory agencies.
• Fourth party – Certification by governmental agencies. In some instances, local, regional or national governmental agencies will require that products be evaluated by the agency or a designated
representative organization for compliance with regulations for installation, use and operation.
Typically, no follow-up monitoring services are provided by the agency. As a result, continued
compliance is often left up to the manufacturer.
112
layout Safe Water.indd 134
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:28
6.5 Conclusions
In order to ensure an effective overall system that will result in the safe and healthy use of
swimming pools and similar recreational environments, it is necessary that these Guidelines inform and be adapted to suit national systems. Figure 6.1 outlines how the Guidelines and the four categories of responsibility outlined within this chapter fit together.
Design &
construction (6.1)
Professional bodies
Training &
self-regulation
Audit and review
Regulatory
requirements (6.4)
• Health & safety
• Construction
• Use of
specified/certified
materials
• Building
• Control of dangerous
substances
Operation &
management(6.2)
Public education &
information (6.3)
Healthy pools and healthy users
Figure 6.1. Linkages between categories of responsibility
6.6 References
American Red Cross (1995) Lifeguarding today. Washington, DC.
Castor Ml, Beach MJ (2004) Reducing illness transmission from disinfected recreational water venues.
Swimming, diarrhea and the emergence of a new public health concern. Pediatric Infectious Disease Journal,
23(9): 866–870.
Goldhaber GM, de Turck MA (1988) Effectiveness of warning signs: ‘familiarity effects’. Forensic Reports,
1: 281–301.
Hill V (1984) History of diving accidents. In: Proceedings of the New South Wales Symposium on Water Safety.
Sydney, New South Wales, Department of Sport and Recreation, pp. 28–33.
ISO (2003) Graphical symbols in safety signs: creating safety signs that everyone comprehends in the same
way. ISO Bulletin, October: 17–21.
Sport England & Health and Safety Commission (2003) Managing health and safety in swimming pools,
3rd ed. Sudbury, Suffolk, UK, HSE Books (HSG Series No. 179).
WHO (2005) Guide to ship sanitation. Geneva, World Health Organization, in preparation.
CHAPTER 6.
layout Safe Water.indd 135
GUIDELINE IMPLEMENTATION
113
24.2.2006 9:57:28
APPENDIX 1
Lifeguards
T
his appendix relates to people who are trained and positioned at swimming pools to protect
water users and who may be paid or voluntary. They may be referred to as lifesavers or lifeguards or given some other title. For simplicity, the term ‘lifeguard’ has been used throughout
this appendix. Box A.1 outlines an example of requirements of a lifeguard, while Box A.2 gives
an example of a lifeguard staffing approach.
BOX A.1 EXAMPLES OF REQUIREMENTS OF THE LIFEGUARD AND THEIR DEPLOYMENT
The lifeguard will normally need to be:
• physically fit, have good vision and hearing, be mentally alert and self-disciplined;
• a strong, able and confident swimmer;
• trained and have successfully completed a course of training in the techniques and practices of
supervision, rescue and first aid in accordance with a syllabus approved by a recognized training
organization.
The deployment of lifeguards would normally take the following into consideration:
• duty spells and structuring of duties – maximum uninterrupted supervision period, working day,
programmed breaks;
• lifeguard numbers – dependent on the pool type, size and usage;
• surveillance zones – observation and scanning requirements;
• supervision of changing facilities – showers, toilets, seating and other areas of potential hazard.
Adapted from Sport England & Health and Safety Commission, 2003
Should the pool be used by groups with their own lifeguards, it is important that the criteria
that apply to the professional pool lifeguard be equally applied to the groups’ lifeguards. Furthermore, there should be documentation on the roles and responsibilities of the groups’ lifeguards:
the hazards and the potential negative health outcomes associated with those hazards are no less
when supervision and management are undertaken by volunteers.
There are a multitude of courses offered for the training and certification of lifeguards. Box
A.3 provides examples of some important elements of lifeguard training. Box A.4 provides an
example of an international pool lifeguard certificate.
114
layout Safe Water.indd 136
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
9.3.2006 15:29:50
BOX A.2 EXAMPLE OF A LIFEGUARD STAFFING APPROACH
In the United Kingdom, lifeguard numbers may be determined as shown in Table A.1 (Sport England &
Health and Safety Commission, 2003).
Table A.1. Lifeguard numbers per square metre of pool
Approximate
pool size (m)
20.0 × 8.5
25.0 × 8.5
25.0 × 10.0
25.0 × 12.5
33.3 × 12.5
50.0 × 20.0
Area (m2)
170
212
250
312
416
1000
Minimum number
of lifeguards (normal)
1
1
1
2
2
4
Minimum number
of lifeguards (busy)
2
2
2
2
3
6
Notes:
1. Where only one lifeguard is on duty, there should be adequate means of summoning assistance rapidly.
2. The ‘water area’ column can be used as a guide for irregular-shaped pools.
The number of lifeguards required for safety can also be calculated based on sweep time and response
time. Some lifeguard training organizations, for example, have created general rules for how quickly
they believe a lifeguard should be expected to observe a person in distress within their supervision
area and how quickly the lifeguard should be able to reach that person. Based on such rules, training
and evaluation, appropriate staffing levels can be derived.
BOX A.3 EXAMPLES OF IMPORTANT ELEMENTS OF LIFEGUARD TRAINING
Public interactions
• Responding to inquiries
• Handling suggestions and concerns
• Addressing uncooperative patrons
• Dealing with violence
• Working with diverse cultures
• Accommodating patrons with disabilities
Responsibilities to facility operations
Preventing aquatic injury
Patron surveillance
Facility surveillance
Emergency preparation
Rescue skills
• General procedures
• Entries
• Approaching the victim
• Victims at or near the surface
• Submerged victims
• Multiple victim rescue
• Removal from the water
• Providing emergency care
APPENDIX 1. LIFEGUARDS
layout Safe Water.indd 137
115
24.2.2006 9:57:29
First aid for injuries
First aid for sudden illnesses
Spinal injury management
• Anatomy and function of the spine
• Recognizing spinal injury
• Caring for spinal injury
• Caring for a victim in deep water
• Spinal injury on land
After an emergency – responsibilities
Adapted from American Red Cross, 1995
BOX A.4 INTERNATIONAL POOL LIFEGUARD CERTIFICATE OF THE INTERNATIONAL LIFE SAVING
FEDERATION
For successful recognition for the International Pool Lifeguard Certificate, the candidate must be able to:
LEARNING OUTCOME 1: Perform water-based fitness skills in a pool environment.
Assessment Criteria:
1.1 Swim 50 m in less than 50 s with the head above the water.
1.2 Swim 400 m in less than 8 min without using equipment.
1.3 Retrieve three objects placed 5 m apart in water approximately 2 m deep, or in the deepest end
of a pool where the depth is less than 2 m.
LEARNING OUTCOME 2: Demonstrate combined rescue without equipment.
Assessment Criteria:
2.1 Consecutively perform combined rescue technique in the following sequence in less than
2 min:
− lifesaving entry (stride jump, slide entry); then,
− 25 m freestyle with head above the water
− surface dive to adult dummy/person (minimum depth of 1.5 m)
− lift the dummy/person and tow minimum of 25 m to the edge of pool
− lift the dummy/person out of the pool.
LEARNING OUTCOME 3: Demonstrate the use of land-based rescue simulation skills.
Assessment Criteria:
3.1 Lift conscious patient and transport them over a minimum distance of 25 m using a recognized
patient transport technique.
3.2 Perform simulated rescue using a throwing aid to a conscious victim in the water over a minimum
distance of 10 m.
LEARNING OUTCOME 4: Perform emergency response techniques including resuscitation and
first-aid techniques.
Assessment Criteria:
4.1 Perform basic patient management techniques, including:
− diagnosis/check for Dangers, Reaction, Airways, Breathing and Circulation (DRABC)
− lateral position & patient rollover
− calling for help
4.2 Perform resuscitation techniques, including:
− Expired Air Resuscitation (adult, child, infant)
116
layout Safe Water.indd 138
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:30
− Cardiopulmonary Resuscitation – CPR (adult, child, infant)
− one- and two-person CPR operation
− set up and apply oxygen equipment
4.3 Identify and perform first-aid techniques for managing injury and emergency, including:
− patient management
− identifying and managing injuries (e.g. shock, fractures, arterial and venal bleeding, spinal injury)
LEARNING OUTCOME 5: Describe medical knowledge about a range of conditions associated with
rescues.
Assessment Criteria:
5.1 Describe the application of appropriate emergency treatments in a rescue situation including CPR
and spinal management.
5.2 Describe the use of medical equipment in emergency situations.
5.3 Identify regulations pertinent to managing emergency medical situations.
5.4 Identify and list medical services available for support in an emergency medical situation.
LEARNING OUTCOME 6: Choose and plan strategies to manage basic emergencies.
Assessment Criteria:
6.1 Identify and select possible strategies for water rescues and emergencies.
6.2 Identify and solve potential problems for putting plans into place.
6.3 Design a basic emergency management plan.
6.4 Practise emergency management plan.
6.5 Review and modify basic emergency management plan.
LEARNING OUTCOME 7: Identify and describe issues related to the facility/workplace.
Assessment Criteria:
7.1 List the specifications of the pool, including depth, access, use of hot tubs, etc.
7.2 List the nearest available safety services.
7.3 Find and use potential resources for use in rescue.
Assessment Strategy:
These learning outcomes are best assessed using the following common assessment methods:
Observation (personal, video review)
Oral questioning
Written examination (short answer, multiple choice)
Simulated rescue scenario
Range of Variables:
There are a number of variables that will affect the performance and assessment of the learning outcomes. These may include:
Variable
• Facilities
• Dress
• Candidates
• Resources
Scope
Swimming pool lengths/depths and measurements (metric/imperial).
Use of alternative aquatic locations where pools are not available.
Identification of equipment that is available for use.
Candidates may be required to wear their recognized uniform.
Candidates will have experience and will be seeking employment or currently
employed as a lifeguard.
International Life Saving Federation member organizations will list and identify
the use of theoretical and practical resources available to them.
Adapted from International Life Saving Federation, 2001
APPENDIX 1. LIFEGUARDS
layout Safe Water.indd 139
117
24.2.2006 9:57:30
References
American Red Cross (1995) Lifeguarding today, Washington, DC.
International Life Saving Federation (2001) International Pool Lifeguard Certificate. Approved by ILS Board
of Directors, September 2001.
Sport England & Health and Safety Commission (2003) Managing health and safety in swimming pools,
3rd ed. Sudbury, Suffolk, UK, HSE Books (HSG Series No. 179).
118
layout Safe Water.indd 140
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
24.2.2006 9:57:30
layout Safe Water.indd 141
24.2.2006 9:57:31
layout Safe Water.indd 142
24.2.2006 9:57:31
layout Safe Water.indd 143
24.2.2006 9:57:31
layout Safe Water.indd 144
24.2.2006 9:57:31
The preparation of this volume has covered a period of over a decade and has involved the participation of numerous institutions and more than 60 experts from
20 countries worldwide. This is the first international point of reference to provide
comprehensive guidance for managing swimming pools and similar facilities so
that health benefits are maximized while negative public health impacts are
minimized.
This volume will be useful to a variety of different stakeholders with interests in
ensuring the safety of pools and similar environments, including national and local
authorities; facility owners, operators and designers (public, semi-public and
domestic facilities); special interest groups; public health professionals; scientists
and researchers; and facility users.
ISBN 92 4 154680 8
GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS VOLUME 2. SWIMMING POOLS AND SIMILAR ENVIRONMENTS
Guidelines for Safe Recreational Water Environments Volume 2: Swimming Pools
and Similar Environments provides an authoritative referenced review and
assessment of the health hazards associated with recreational waters of this type;
their monitoring and assessment; and activities available for their control through
education of users, good design and construction, and good operation and
management. The Guidelines include both specific guideline values and good
practices. They address a wide range of types of hazard, including hazards leading
to drowning and injury, water quality, contamination of associated facilities and
air quality.
Guidelines for
safe recreational water
environments
VOLUME 2
SWIMMING POOLS AND
SIMILAR ENVIRONMENTS
WHO
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising