Mold Prevention Strategies/Possible Health Effects

Mold Prevention Strategies/Possible Health Effects
Mold Prevention Strategies and Possible Health Effects in
the Aftermath of Hurricanes and Major Floods
Extensive water damage after major hurricanes and floods increases the likelihood of
mold contamination in buildings. This report provides information on how to limit
exposure to mold and how to identify and prevent mold-related health effects. Where
uncertainties in scientific knowledge exist, practical applications designed to be
protective of a person's health are presented. Evidence is included about assessing
exposure, clean-up and prevention, personal protective equipment, health effects, and
public health strategies and recommendations. The recommendations assume that, in
the aftermath of major hurricanes or floods, buildings wet for >48 hours will generally
support visible and extensive mold growth and should be remediated, and excessive
exposure to mold-contaminated materials can cause adverse health effects in
susceptible persons regardless of the type of mold or the extent of contamination.
For the majority of persons, undisturbed mold is not a substantial health hazard. Mold is
a greater hazard for persons with conditions such as impaired host defenses or mold
allergies. To prevent exposure that could result in adverse health effects from disturbed
mold, persons should 1) avoid areas where mold contamination is obvious; 2) use
environmental controls; 3) use personal protective equipment; and 4) keep hands, skin,
and clothing clean and free from mold-contaminated dust.
Clinical evaluation of suspected mold-related illness should follow conventional clinical
guidelines. In addition, in the aftermath of extensive flooding, health-care providers
should be watchful for unusual mold-related diseases. The development of a public
health surveillance strategy among persons repopulating areas after extensive flooding
is recommended to assess potential health effects and the effectiveness of prevention
efforts. Such a surveillance program will help CDC and state and local public health
officials refine the guidelines for exposure avoidance, personal protection, and clean-up
and assist health departments to identify unrecognized hazards.
On August 29 and September 24, 2005, hurricanes Katrina and Rita, respectively, made
landfall along the Gulf Coast. After both storms, levees were breached, leading to
massive flooding in New Orleans and surrounding parishes.
The duration of flooding, the extent of flooding, and the number of structures flooded in
New Orleans as a result of hurricanes Katrina and Rita in August and September 2005
made the likelihood of massive mold contamination a certainty. Many structures
remained flooded for weeks after the hurricane and became saturated with water. An
assessment of homes in New Orleans (Orleans Parish) and the surrounding parishes of
St. Bernard, East Jefferson, and West Jefferson (excluding the 9th Ward) identified an
estimated 46% (>100,000 homes) with some mold contamination; approximately 17%
(40,000 homes) had heavy mold contamination (1). [CIRI Note on References and
Tables: more detail and correlation with numbers and tables in the text are available in
Recent parallels to the kind of flooding observed in New Orleans as a result of
hurricanes Katrina and Rita occurred in 1997 in Grand Forks, North Dakota, and in 1999
in North Carolina after Hurricane Floyd (2). The number of structures affected was much
smaller in North Dakota than in New Orleans, and the population affected in North
Carolina was much more dispersed than the population affected in New Orleans. In
North Carolina, a reported increase in persons presenting with asthma symptoms was
postulated to be caused by exposure to mold (2). In 2001, flooding and subsequent
mold growth on the Turtle Mountain reservation in Belcourt, North Dakota was
associated with self-reports of rhinitis, rash, headaches, and asthma exacerbation (3).
This document was initially prepared by CDC as a guide for public health officials and
the general public in response to the massive flooding and the anticipated mold
contamination of homes and other structures along the U.S. Gulf Coast associated with
hurricanes Katrina and Rita (4). A workgroup was convened of CDC staff with expertise
in relevant subject areas. This included medical epidemiologists, environmental
epidemiologists and occupational epidemiologists, industrial hygienists, infectious
disease physicians and mycologists. The framework for the document was decided by
consensus discussions, and workgroup members were assigned to research and to
write different sections. The members produced individual written summaries, which
formed the basis of the report. Wherever possible, recommendations were based on
existing recommendations or guidelines. Where adequate guidelines did not exist, the
guidelines were based on CDC experience and expertise.
This revised version is intended to more broadly address public health concerns related
to limiting exposure to mold and identifying, preventing, and managing mold-related
health effects following any natural disasters or other occurrences that results in
flooding or major water intrusion. Published guidelines, established standards, and the
peer-reviewed literature were reviewed to ensure the accuracy and consistency of the
recommendations. In addition, the document was sent for stakeholder review and
external peer review by experts in the areas of worker protection, general public health,
medical, environmental and occupational epidemiology, allergy, industrial hygiene,
mycology, and pulmonology.
Mold: A Definition
Molds, mushrooms, mildews, and yeasts are all classified as fungi, a kingdom of
organisms distinct from plants and animals. Fungi differ from plants and animals in
several respects. Unlike animals, fungi have cell walls. However, unlike plants, which
also have cell walls, fungal cell walls are made mostly of chitin and glucan. Fungi
cannot produce their own nutrients as plants do through photosynthesis. Fungi secrete
enzymes that digest the material in which the fungi are imbedded and absorb the
released nutrients. Multicellular fungi do not differentiate into different organs or
functional components the way plants and animals do (5).
Approximately 100,000 species of fungi exists; fewer than 500 fungal species have
been described as human pathogens that can cause infections (5). Visible growth of
multicellular fungi consisting of branching filamentous structures (mycelia) are known
popularly as molds (5) and are referred to by that term in this report.
Molds are ubiquitous in nature and grow almost anywhere indoors or outdoors. The
overall diversity of fungi is considerable. For example, the genus Aspergillus has at
least 185 known species (6). Molds spread and reproduce by making spores, which are
small and lightweight, able to travel through air, capable of resisting dry, adverse
environmental conditions, and capable of surviving a long time. The filamentous parts of
mold (hyphae) form a network called mycelium, which is observed when a mold is
growing on a nutrient source. Although these mycelia are usually firmly attached to
whatever the mold is growing on, they can break off, and persons can be exposed to
fungal fragments. Some micro-organisms, including molds, also produce characteristic
volatile organic compounds (VOCs) or microbial VOCs (mVOCs). Molds also contain
substances known as beta glucans; mVOCs and beta glucans might be useful as
markers of exposure to molds (7).
Some molds are capable of producing toxins (sometimes called mycotoxins) under
specific environmental conditions, such as competition from other organisms or
changes in the moisture or available nutrient supply. Molds capable of producing toxins
are popularly known as toxigenic molds; however, use of this term is discouraged
because even molds known to produce toxins can grow without producing them (6).
Many fungi are capable of toxin production, and different fungi can produce the same
toxin (6).
Factors That Produce Mold Growth
Although molds can be found almost anywhere, they need moisture and nutrients to
grow. The exact specifications for optimal mold growth vary by the species of mold.
However, mold grows best in damp, warm environments. The availability of nutrients in
indoor environments rarely limits mold growth because wood, wallboard, wallpaper,
upholstery, and dust can be nutrient sources. Similarly, the temperature of indoor
environments, above freezing and below the temperature for denaturing proteins, can
support mold growth, even if the actual temperature is not optimal (8).
The primary factor that limits the growth of mold indoors is lack of moisture. Substantial
indoor mold growth is virtually synonymous with the presence of moisture inside the
building envelope. This intrusion of moisture might be from rainwater leaking through
faulty gutters or a roof in disrepair, from a foundation leak, from condensation at an
interface (e.g., windows or pipes), or between a cold and a warm environment. Water
also can come from leaks in the plumbing or sewage system inside the structure.
Studies of mold growth on building materials, such as plywood, have found that mold
grows on materials that remain wet for 48--72 hours (8). Flooding, particularly when
floodwaters remain for days or weeks, provides an almost optimal opportunity for mold
How Persons Are Exposed to Mold
Mold exposure can produce disease in several ways. Inhalation is usually presumed to
be the most important mechanism of exposure to viable (live) or nonviable (dead) fungi,
fungal fragments or components, and other dampness-related microbial agents in
indoor environments. The majority of fungal spores have aerodynamic diameters of 2-10 µm, which are in the size range that allow particles to be deposited in the upper and
lower respiratory tract (5). Inhalation exposure to a fungal spore requires that the spore
be initially aerosolized at the site of growth. Aerosolization can happen in many ways,
ranging from disturbance of contaminated materials by human activity to dispersal of
fungi from contaminated surfaces in heating, ventilating, and air-conditioning (HVAC)
systems. Fungal spores also can be transported indoors from outdoors. Overall, the
process of fungal-spore aerosolization and related issues (e.g., transport, deposition,
resuspension, and tracking of fungi to other areas) are poorly understood.
Persons can be exposed to mold through skin contact, inhalation, or ingestion. Because
of the ubiquity of mold in the environment, some level of exposure is inevitable. Persons
can be exposed to mold through contact with airborne spores or through contact with
mycelial fragments. Exposure to high airborne concentrations of mold spores could
occur when persons come into contact with a large mass of mold, such as might occur
in a building that has been flooded for a long time. Exposure to mycelia fragments could
occur when a person encounters a nutrient source for mold that has become disrupted,
such as would occur during removal of mold-contaminated building material. Skin
contact or exposure by inhalation to either spores or mycelial fragments also could
occur in a dusty environment, if the components of dust include these fungal elements.
For the majority of adverse health outcomes related to mold exposure, a higher level of
exposure to living molds or a higher concentration of allergens on spores and mycelia
results in a greater likelihood of illness. However, no standardized method exists to
measure the magnitude of exposure to molds. In addition, data are limited about the
relation between the level of exposure to mold and how that causes adverse health
effects and how this relation is affected by the interaction between molds and other
microorganisms and chemicals in the environment. For this reason, it is not possible to
sample an environment, measure the mold level in that sample, and make a
determination as to whether the level is low enough to be safe or high enough to be
associated with adverse health effects.
Persons affected by major hurricanes or floods probably will have exposure to a wide
variety of hazardous substances distributed by or contained within the floodwater. This
report does not provide a comprehensive discussion of all such potential hazards; such
situations will of necessity require case by case evaluation and assessment. Guidance
has been provided by CDC for such issues in a number of documents, including NIOSH
Hazard Based Interim Guidelines: Protective Equipment for Workers in Hurricane Flood
Response (9) and the CDC guidance: Protect Yourself From Chemicals Released
During a Natural Disaster (10).
Factors That Cause Disease from Mold
Numerous species of mold cause infection through respiratory exposure. In general,
persons who are immunosuppressed are at increased risk for infection from mold (11).
Immunosuppression can result from immunosuppressive medication, from medical
conditions and diseases that cause immunosuppression, or from therapy for cancer that
causes transient immunosuppression. Although certain species of mold cause infection
(5,8,11), many mold species do not cause infection. Infections from mold might be
localized to a specific organ or disseminated throughout the body.
Many of the major noninfectious health effects of mold exposure have an immunologic
(i.e., allergic) basis (6). Exposure to mold can sensitize persons, who then might
experience symptoms when re-exposed to the same mold species. For sensitized
persons, hay fever symptoms and asthma exacerbations are prominent manifestations
of mold allergy (6). Although different mold species might have different propensities to
cause allergy, available data do not permit a relative ranking of species by risk for
creating or exacerbating allergy. In addition, exposure to beta glucans might have an
inflammatory effect in the respiratory system (12).
Prolonged exposure to high levels of mold (and some bacterial species) can produce an
immune-mediated disease known as hypersensitivity pneumonitis (13). Clinically,
hypersensitivity pneumonitis is known by the variety of exposures that can cause this
disorder (e.g., farmer's lung, woodworker's lung, and malt worker's lung).
Ingesting toxins that molds produce can cause disease. Longterm ingestion of aflatoxins
(produced by Aspergillus species) has been associated with hepatocellular cancer (14).
In addition, ingestion of high doses of aflatoxin in contaminated food causes
aflatoxicosis and can result in hepatic failure (11). Whether concentrations of airborne
mold toxins are high enough to cause human disease through inhalation is unknown,
and no health effects from airborne exposure to mold-related toxins are proven.
General Guidelines
Assessing Exposure to Mold
Exposure Assessment
Any structure flooded after hurricanes or major floods should be presumed to contain
materials contaminated with mold if those materials were not thoroughly dried within 48
hours (15,16). In such cases, immediate steps to reduce the risk for exposure to mold
are likely to be of greater importance than further exposure assessment steps
presented below.
Assessing the level of human exposure to mold in flooded buildings where mold
contamination is not obvious is often a central and ongoing activity in recovery related to
hurricanes and floods. Understanding the strengths and limitations of the approaches
that are available to assess such exposures is important. Buildings that were not
flooded could also have mold. For example, buildings with leaking roofs or pipes, which
allows water to penetrate into biodegradable building materials, or excessive humidity,
particularly buildings built with biodegradable materials, are susceptible to mold growth
Visual Inspection and Moisture Assessment
A visual inspection is the most important step in identifying possible mold contamination
(17,18). The extent of any water damage and mold growth should be visually assessed.
This assessment is particularly important in determining remedial strategies and the
need for personal protective equipment (PPE) for persons in the contaminated area.
Ceiling tiles, gypsum wallboard (sheetrockTM), cardboard, paper, and other cellulosic
surfaces should be given careful attention during a visual inspection. Not all mold
contamination is visible (9,16); with a flood, contamination in the interior wall cavities or
ceiling is common. A common means of assessing the mold contamination of a building
is to estimate the total square feet of contaminated building materials (9,18,19).
However, professional judgment will necessarily play an important role in the visual
inspection because less quantifiable factors (e.g., location of the mold, building use, and
function) and exposure pathways are also important in assessing potential human
exposure and health risks.
Ventilation systems also should be visually checked, particularly for damp filters, damp
conditions elsewhere in the system, and overall cleanliness. To avoid spreading
microorganisms throughout the building, HVAC systems known or suspected to be
contaminated with mold should not be run. Guidelines from the U.S. Environmental
Protection Agency (EPA) and CDC (20,21) provide useful information concerning this
topic. Different algorithms for assessing and remediating mold-contaminated buildings
are available. Examples of such algorithms are available from the U.S. Army (22), the
New York City Department of Health (18), and OSHA (23).
Moisture meters provide qualitative moisture levels in building materials and might be
helpful for measuring the moisture content in a variety of building materials (e.g., carpet,
wallboard, wood, brick, and concrete) following water damage (9,17). Meters also can
be used to monitor progress in drying wet materials. Damaged materials should be
removed and discarded. Moisture meters are available from contractor tool and supply
outlets. Humidity meters can be used to monitor indoor humidity. Inexpensive (<$50)
models that monitor both temperature and humidity are available.
A borescope is a hand-held tool that allows users to see hidden mold problems inside
walls, ceiling plenums, crawl spaces, and other tight areas (6,18). No major drilling or
cutting of dry wall is required.
Sampling for Mold
Sampling for mold is not part of a routine building assessment (9,16,18,19). In most
cases, appropriate decisions about remediation and the need for PPE can be made
solely on the basis of visual inspection. If visible mold is present, then it should be
remediated regardless of what types of microorganisms are present, what species of
mold is present, and whether samples are taken. Other than in a controlled, limited,
research setting, sampling for biologic agents in the environment cannot be
meaningfully interpreted and would not substantially affect relevant decisions about
remediation, reoccupancy, handling or disposal of waste and debris, worker protection
or safety, or public health. If sampling is being considered, a clear purpose should exist.
For example:
To help evaluate a source of mold contamination. For example, testing the types of
mold and mold concentrations indoors versus outdoors can be used to identify an
indoor source of mold contamination that might not be obvious on visual inspection.
To help guide mold remediation. For example, if mold is being removed and it is
unclear how far the colonization extends, then surface or bulk sampling in combination
with moisture readings might be useful.
Types of Samples. Types of samples used to assess the presence of mold and the
potential for human exposure to mold in a water-damaged building include air samples,
surface samples, bulk samples, and water samples from condensate drain pans or
cooling towers. Detailed descriptions of sampling and analysis techniques have been
published (6,17).
Among the types of samples, airborne sampling might be a good indicator of exposure
from a theoretical point of view, particularly for assessing acute short-term exposures.
However, in practice, many problems (e.g., detection problems and high variability over
time) limit the usefulness of these types of samples for most biologic agents. If air
sampling is conducted, personal measurements best represent the current exposure,
although practical constraints might make personal sampling difficult. Therefore, area
sampling is the most commonly performed type of air sampling used to assess
bioaerosol exposure despite resultant uncertainty about how accurately the
measurements reflect actual personal exposure.
One type of surface sampling is the sampling of settled dust. A theoretical advantage of
settled-dust sampling is the presumed correlation of concentrations of fungi in the
settled dust with chronic exposure to those fungi (17). However, surface sampling is a
crude measure and will yield a poor surrogate for airborne concentrations (6,17).
Results of surface sampling as a measure of exposure should be interpreted with
caution. Bulk samples can provide information about possible sources of biologic agents
in buildings and the general composition and relative concentrations of those biologic
Assessment of Microorganisms. Two distinct approaches are used for evaluation of the
presence of specific microbes: culture-based and nonculture-based. The strengths and
limitations of the different approaches have been published (6).
Instead of measuring culturable or nonculturable fungi or fungal components,
constituents or metabolites of microorganisms can be measured as a surrogate of
microbial exposure. Examples of such techniques include polymerase chain reaction
(PCR) technologies and immunoassays (6,17). Methods for measuring microbial
constituents (with some exceptions) are in an experimental phase and have not yet
been routinely applied in clinical assessments, risk assessments, or epidemiologic
No health-based standards (e.g., OSHA or EPA standards) or exposure limits (e.g.,
NIOSH recommended exposure limits) for indoor biologic agents (airborne
concentrations of mold or mold spores) exist. Differences in season; climatic and
meteorological conditions; type, construction, age, and use of the building and
ventilation systems; and differences in measurement protocols used in various studies
(e.g., viable versus nonviable microorganism sampling, sampler type, and analysis)
make it difficult to interpret sampling data relative to information from the medical
literature (6,17). If sampling is performed, exposure data can be evaluated (either
quantitatively or qualitatively) by comparing exposure data with background data, indoor
environments with outdoor environments, or problem areas with nonproblem areas. A
quantitative evaluation involves comparing exposures, whereas a qualitative evaluation
could involve comparing species or genera of microorganisms in different environments.
Specifically, in buildings without mold problems, the qualitative diversity of airborne
fungi indoors and outdoors should be similar. Conversely, the dominating presence of
one or two kinds of fungi indoors and the absence of the same kind outdoors might
indicate a moisture problem and degraded air quality. In addition, the consistent
presence of fungi such as Stachybotrys chartarum, Aspergillus versicolor or various
Penicillium species over and beyond background concentrations might indicate a
moisture problem that should be addressed (17). Indoor and outdoor mold types should
be similar, and indoor levels should be no greater than levels outdoors or in
noncomplaint areas (17). Analytical results from bulk material or dust samples also
might be compared with results of similar samples collected from reasonable
comparison areas.
Other Issues
For biologic agents, few biomarkers of exposure or dose have been identified, and their
validity for exposure assessment in the indoor environment is often unknown. Testing to
determine the presence of immunoglobulin E (IgE) to specific fungi might be a useful
component of a complete clinical evaluation in the diagnosis of illnesses (e.g., rhinitis
and asthma) that can be caused by immediate hypersensitivity (17,24). Testing is
usually done by in vitro tests for serum specific IgE, or by skin prick or puncture tests.
Detection of immunoglobulin G (IgG) to specific fungi has been used as a marker of
exposure to agents that might cause illnesses such as hypersensitivity pneumonitis
(17,24). However, the ubiquitous nature of many fungi and the lack of specificity of
fungal antigens limit the usefulness of these types of tests in evaluating possible
building-related illness and fungal exposure (17,24). Specific serologic tests (e.g., tests
for cryptococcal antigen, coccidioidal antibody, and Histoplasma antigen) are useful in
the diagnosis of some fungal infections, but these are the exception. The routine clinical
use of immunoassays as a primary means of assessing environmental fungal exposure
or health effects related to fungal exposure is not recommended. Health-care providers
whose patients express concern about the relation between symptoms and possible
exposure to fungi are advised to use immunoassay results with care and only in
combination with other clinical information, including history, physical findings, and other
laboratory results (24).
In recent years, increased concern has arisen about exposure to specific molds that
produce substances called mycotoxins. Health effects related to mycotoxins are
generally related to ingestion of large quantities of fungal-contaminated material (17).
No conclusive evidence exists of a link between indoor exposure to airborne mycotoxin
and human illness (6,25). Many molds can potentially produce toxins given the right
conditions (6,11,17). Some molds that produce mycotoxins are commonly found in
moisture-damaged buildings; research related to the importance of these findings is
ongoing. Although the potential for health problems is an important reason to prevent or
minimize indoor mold growth and to remediate any indoor mold contamination, evidence
is inadequate to support recommendations for greater urgency of remediation in cases
where mycotoxin-producing fungi have been isolated.
The interpretation of environmental sampling data generally requires professional
judgment, and medical conclusions cannot be made based solely on the results of
analysis of environmental sampling. In the context of mold growth following a major
hurricane or flood, mold growth itself and the extent of growth based on a thorough
visual inspection is sufficient to categorize a building as moldy or not moldy. This should
provide sufficient information for action and no additional characterization is needed.
Clean-up and Prevention
The most effective way to eliminate mold growth is to remove it from materials that can
be cleaned and to discard materials that cannot be cleaned or are physically damaged
beyond use (9,18,19,26--30). Persons with respiratory conditions, allergies, asthma, or
weakened immune systems should avoid mold cleanup if possible or seek the advice of
their doctor and determine what type of personal protective equipment is appropriate.
Appropriate PPE (e.g., tight-fitting NIOSH-approved N-95 respirator, gloves to limit
contact of mold and cleaning solutions with skin, and goggles) (13,26--30) should be
used when performing clean-up or other activities in mold-contaminated homes or
buildings after a flood.
Removing mold problems requires a series of actions (6,9,16). The order of these
actions is sometimes important (6), but might vary on a case-by-case basis. Typically,
the following actions are taken regardless of whether a problem is small and simple or
large and complex:
Take emergency action to stop water intrusion, if needed.
Determine the extent of water damage and mold contamination.
Plan and implement remediation activities.
--- If needed, establish containment and protection for workers and occupants.
--- Eliminate or limit water or moisture sources.
--- Decontaminate or remove damaged materials, as appropriate.
--- Dry any wet materials, if possible.
--- Evaluate whether space has been successfully remediated.
--- Reassemble the space to prevent or limit possibility of recurrence by controlling
sources of moisture.
For small, simple problems, the entire list of tasks can be done by one person. Large,
complex problems might require many persons from different professions and trades.
For circumstances that fall between those extremes, some combination of occupant
action and professional intervention will be appropriate. In general, no single discipline
brings together all the required knowledge for successful assessment and remediation.
Returning to Mold-Contaminated Homes or Buildings After a Flood
When persons return to homes or buildings after a flood, they should take the following
steps (6,9,16,26--30):
Clean up and dry out the building quickly. Open doors and windows and use fans or
dehumidifiers to dry out the building.
Remove all porous items that have been wet for >48 hours and that cannot be
thoroughly cleaned and dried. These items can remain a source of mold growth and
should be removed from the home or building. Porous, noncleanable items include
carpeting and carpet padding, upholstery, wallpaper, drywall, ceiling tiles, insulation
material, some clothing, leather, paper, some wood and wood products, and food.
Removal and cleaning are important because even dead mold can cause allergic
Clean wet items and surfaces with detergent and water to prevent mold growth.
Temporarily store damaged or discarded items outside the home or building until
insurance claims can be processed.
Removing and Cleaning Up Mold in a Building
For cleaning mold covering <10 square feet in an area flooded by clean water,
detergent and water might be adequate (9,16). However after hurricanes and major
floods, flood water is likely to be contaminated and, in this setting, mold can be removed
with a bleach solution of 1 cup chlorine bleach per 1 gallon of water (26--30). Never mix
bleach or bleach-containing products with ammonia or ammonia-containing products. If
water damage is substantial or mold growth covers >10 square feet, consult the EPA
guide, Mold Remediation in Schools and Commercial Buildings (15).
Some companies specialize in water damage restoration and can assess the issues
involved in cleaning up homes after a flood. Two professional trade groups that might
be able to help locate such an expert are the Association of Specialists in Cleaning and
Restoration ( and the Institute of Inspection, Cleaning, and
Restoration Certification (
Contractors used for remediation should have experience in cleaning mold. Check
references and ask the contractor to follow the recommendations in the guidelines of
the American Conference of Governmental Industrial Hygienists (ACGIH) or other
guidelines from professional organizations or state agencies. Contact your state health
department's website for information about state licensing requirements for contractors
in your state. Examples of websites from states that have recently dealt with natural
disasters include (Texas) and (Louisiana).
Cleaning Clothes, Textiles, or Stuffed Animals
Ensure that laundry is washed in safe water. Use only water that is properly disinfected
or that the authorities have stated is safe. Take the appropriate steps to make sure that
use of gas or electric appliances is safe.
Before using a washing machine that was in a flooded building, run the machine
through one full cycle before washing clothes. Use hot water and a disinfectant or
sanitizer. Take clothes and linens outdoors and shake off any dried mud or dirt before
washing them. Hose off muddy items to remove all dirt before putting them in the
If the items are only wet, they can be laundered normally. Check the labels on clothes
and linens and wash them in detergent and warm water if possible, or take them to a
professional cleaner. Adding chlorine bleach to the wash cycle will remove most mildew
and will sanitize the clothing. However, bleach might fade some fabrics and damage
other fabrics. If the label reads "dry clean only," shake out loose dirt and take the item to
a professional cleaner.
Consult a remediation professional for advice on whether heavily mold-contaminated
items made of leather, suede, or a similar material are salvageable or should be
discarded. Do not burn or bury textiles that cannot be cleaned. Put them into properly
sealed plastic bags and dispose of them as you would normal household garbage in
your area.
Salvaging Household Items
When assessing or remediating mold contamination to a house, homeowners or cleanup personnel might decide to repair or clean household items (e.g., housewares or
kitchen items) damaged or contaminated by flood waters. As with clothing and other
textiles, make sure the water being used is safe. Use only water that is properly
disinfected or that the authorities have stated is safe.
Nonporous items (e.g., dishes, pots, glass items, and hard plastic items) can be
salvaged. However, because floodwaters are contaminated, nonporous items should be
washed by hand in a disinfectant and then air-dried. Do not use a dish towel. Porous
items (e.g., cloth, some wood and wood products, and soft plastic) must be discarded
because they probably absorbed whatever contaminants were in the floodwaters.
Before using the dishwasher, clean and disinfect it. Then use a hot setting to wash your
pots, pans, dishes, and utensils. Do not use the energy-saving setting. Throw away
canned foods that are bulging, opened, or damaged. Food containers with screw-caps,
snap-lids, crimped caps (soda pop bottles), twist caps, flip tops, snap-open, and homecanned foods should be discarded if they have come into contact with floodwater
because they cannot be disinfected. If intact cans have come in contact with floodwater
or storm water, remove the labels, wash the cans, and dip them in a solution of 1 cup of
bleach in 5 gallons of water. Relabel the cans with a marker.
Cleaning a Heating, Ventilating, and Air Conditioning System
All surfaces of an HVAC system and all its components that were submerged during a
flood are potential reservoirs for dirt, debris, and microorganisms, including bacteria and
mold. In addition, moisture can collect in areas of HVAC system components that were
not submerged (e.g., air supply ducts above the water line), and this also can lead to
the growth of microorganisms. Therefore, all flood water-contaminated and moistureladen components of the HVAC system should be thoroughly inspected, cleaned of dirt
and debris, and disinfected by a qualified professional. CDC has prepared
recommendations for professionals to help ensure that floodwater-contaminated HVAC
system components are properly cleaned and remediated (21). If HVAC systems are
not properly cleaned and disinfected to prevent the dissemination of mold and other
debris throughout a building, bioaerosols of mold and other microorganisms might exists
and can cause a variety of adverse health effects to the building's occupants. Ensure
that the HVAC system is shut down before any remedial activities.
Prevention After the Flood
Limited scientific information exists on the efficacy and impact of prevention strategies.
In addition, little of the practical knowledge acquired and applied by design,
construction, and maintenance professionals has been subject to thorough validation
(6). No generally accepted health-based standards exist for remediation (6).
If property owners decide to make extensive repairs or completely rebuild after a flood,
they might consider designing and building in a way that will limit the potential for future
mold growth (6,30). The key to prevention of mold is to eliminate or limit the conditions
that foster microbial growth by limiting water intrusion and the nutrients that allow mold
to grow (6,9,16,30). The two basic approaches are to keep moisture-sensitive materials
dry and to use materials that are not easily biodegradable or which offer a poor
substrate for mold growth.
Personal Protective Equipment
Workers and their employers might be required to wear or provide protection to
minimize exposure to mold. Workers and employers should refer to pertinent OSHA
standards and NIOSH guidelines. Information also is provided for the public.
Minimizing exposure to mold involves using PPE and administrative and engineering
controls (6,17,18,31,32). Administrative controls include identifying mold-contaminated
areas promptly, restricting access to these areas, and minimizing aerosol generating
activities (e.g., by suppressing dust) (3,6,18,27,29,32). Engineering controls include
ventilating mold-contaminated areas adequately and using heavy equipment with
sealed positive pressure, air-conditioned cabs that contain filtered air recirculation units
to protect the workers (6,17,18,31,32). Misting contaminated materials with water is a
control measure used to reduce dust levels during debris removal.
Workers should wear PPE regardless of the engineering controls used, especially for
skin and eye protection (1,9,17,18,32). Primary functions of PPE in a moldcontaminated environment are prevention of the inhalation and ingestion of mold and
mold spores and prevention of mold contact with skin or eyes (1,32). PPE requirements
for workers are likely to differ from the PPE recommendations for homeowners or other
building occupants who are less likely to disturb and aerosolize contaminated materials.
In addition, PPE recommendations for persons with underlying illness or compromised
immune systems will differ from PPE recommendations for healthy persons. Proper
training or instruction in the use of protective equipment is essential for effective use.
Guidelines for protection of and training recommendation for workers have been
published (33).
Types of Personal Protective Equipment
Skin and Eye Protection
Gloves keep the hands clean and free from contact with mold (9,29). Gloves also
protect hands from potentially irritating cleaning solutions (29,32,33). Long gloves that
extend to the middle of the forearm are recommended. The glove material should be
selected on the basis of the type of substance or chemical being handled. When using a
biocide (e.g., chlorine bleach) or a strong cleaning solution, gloves made from natural
rubber, neoprene, nitrile, polyurethane, or PVC are needed. When using a mild
detergent or plain water, ordinary household rubber gloves can be used. Latex or
nonlatex medical examination gloves should be used if hands are likely to be in contact
with infectious materials. Persons with natural rubber latex allergy should not use
natural rubber latex gloves and should consult the NIOSH Alert on latex gloves for
further information (34).
To protect eyes, properly fitted goggles or a full face-piece respirator are needed.
Goggles must be designed to prevent the entry of dust and small particles. Safety
glasses or goggles with open vent holes are not appropriate in mold remediation. CDC
has published guidelines on this topic (35).
Protective Clothing
When conducting building inspections and remediation work, workers or homeowners
might encounter hazardous biologic agents and chemical and physical hazards.
Consequently, appropriate personal protective clothing, either reusable or disposable, is
recommended to minimize cross-contamination between work areas and clean areas, to
prevent the transfer and spread of mold and other contaminants to street clothing, and
to eliminate skin contact with mold or chemicals (9,32). In hot environments,
precautions to prevent dehydration and heat stress when wearing protective clothing
(e.g., drink plenty of water) are needed.
Disposable PPE should be discarded after it is used. Such equipment should be placed
into impermeable bags and usually can be discarded as ordinary construction waste.
Protective equipment for biocide applicators (e.g., goggles or face shield, aprons or
other protective clothing, gloves, and respiratory protection) must be selected on the
basis of the product manufacturer's warnings and recommendations. In addition, the
manufacturer's recommended precautions should be followed. Reusable protective
clothing, including respiratory equipment (36,37), should be cleaned according to
manufacturers' recommendations for PPE exposed to mold and other potentially
hazardous chemicals (e.g., bleach and biocides).
Respiratory Protection
Inhalation is the primary exposure route of concern related to mold for workers,
homeowners, and building occupants (6,9,17,18). When administrative and engineering
controls are not adequate to eliminate airborne exposure to mold (or dust containing
mold), respirators provide additional protection from inhalation of airborne mold,
contaminated dust, and other particulates that are released during dust-generating
processes (e.g., remediation work or debris removal) (6,9,17).
Respirators provide varying levels of protection. Selecting a respirator to minimize
exposure to molds should be based on a qualitative assessment because quantitative
data on mold-contaminated environments are not informative (38--41). All decisions
about respirator selection should be made with knowledge of the relative protective
capabilities and the advantages and disadvantages of different respirators. Further
discussion of respirator selection is available (38--41).
Standard surgical or dust masks are intended for use only as barriers against large
particles and do not provide protection against many airborne particles (38). Respirators
used to protect persons from airborne contaminants (including mold and mold spores)
must be certified by CDC's NIOSH. In addition, as specified by the OSHA respiratory
protection standard (37), workers whose employers require them to use respirators
must be properly trained, have medical clearance, and be properly fit-tested before they
use the respirator. If a worker must use respirators, the worker's employer must develop
and implement a written respiratory protection program with worksite-specific
procedures and elements. Additional information on respiratory protection is available
from OSHA (37,42,43).
PPE Guidelines for Workers in Mold-Contaminated Areas
Exposure to some level of airborne mold is inevitable because molds are found indoors
and outdoors (6,17). However, demolishing or cleaning heavily mold-contaminated
materials outdoors can lead to excessive exposure to mold. The level of exposure to
mold outdoors is primarily based on the amount of mold-contaminated material, the
amount of mold in the material, and the type of work being performed. The need for
PPE (including respiratory, skin, and eye protection) for outdoor workers requires
ongoing professional assessment that considers the potential for exposure to mold and
the potential for exposure to other hazardous substances that might be in the outdoor
work area.
Guidelines summarized below are based on guidelines from OSHA (37,42,43), EPA
(13), and the New York City Department of Health and Mental Hygiene (18). These
guidelines recommend particular respirators on the basis of the size of the area of mold
contamination. However, the size criteria are based on general professional judgment
and practicality because data are limited related to the extent of contamination to the
frequency or severity of health effects.
When determining the potential for airborne exposure to mold and the need for PPE, the
size of the area is not the only criterion to be considered. The activities being performed
in relation to the mold-contaminated materials are at least as important. Therefore,
ongoing professional judgment always must play a part in decisions concerning PPE.
For example, any remediation or other work that disturbs mold and causes mold spores
to become airborne increases the degree of respiratory exposure. Actions that tend to
disperse mold include breaking apart moldy porous materials such as wallboard;
destructive invasive procedures to examine or remediate mold growth in a wall cavity;
removal of contaminated wallpaper by stripping or peeling; and using fans to dry items
or ventilate areas. In addition, health status and other characteristics of the persons
potentially exposed to mold also might need to be considered.
Category I Protection
Respiratory protection (e.g., N-95 disposable respirator). Respirators must be used in
accordance with the OSHA respiratory protection standard (9,37).
Gloves and eye protection.
For use while cleaning the following:
Small isolated areas (<10 square feet) of heating, ventilation, and HVAC systems
(includes pipes, ducts, and vents).
Isolated areas (<100 square feet) of building materials (e.g., ceiling tiles, small areas
on walls, and individual or multiple wallboard panels).
Category II Protection
Respiratory protection with full face-piece respirators, with N100, R100, P100 (or for
powered air purifying respirators, HEPA) particulate filters. Respirators must be used in
accordance with the OSHA respiratory protection standard (13).
Disposable protective clothing covering entire body including both head and shoes.
For use while cleaning the following:
Large contaminated areas (>10 square feet) of HVAC systems.
Extensively contaminated (>100 contiguous square feet) building materials.
Any size area where substantial dust is generated during cleaning or debris removal
(e.g., when abrasives must be used to clean contaminated surfaces or plaster walls are
being demolished).
Areas where the visible concentration of mold is heavy (blanket coverage rather than
These guidelines should be followed according to professional judgment. For example,
more protective respirators might be required if toxic contaminants such as asbestos or
lead are encountered during cleanup. All workers dealing with large areas of
contamination should be properly trained to handle hazardous materials.
PPE Guidelines for the Public (Nonworkers) in Residences and Nonoccupational
Clean-up, Debris Removal, or Similar Activities
The activities (and possible exposure to mold) of persons re-entering their homes or
working outside might be similar to those of workers. Preventing the creation of dust
and limiting exposure to dust are the best ways to minimize exposure to mold (1,9,18).
For example, using wet mops or vacuums with HEPA filters instead of dry sweeping
dust and debris will decrease the amount of dust in the air (1,9,18).
If building occupants, residents, or anyone must be around mold-contaminated dust,
respirators will offer some protection. Particulate respirators (such as NIOSH-certified
N-95 respirators) can be purchased in safety supply stores and in most home
improvement stores. Several factors are required for respirators to provide protection
from inhalation hazards (15,38,41,43):
The respirator must fit well and be worn correctly. The manufacturer's instructions on
the package should be followed. Because respirators are meant to be used by healthy
workers who have had training, medical evaluations, and a proper fitting, the amount of
protection provided by a respirator to the general public might be much less.
No U.S. agency tests and certifies respirators for public use. However, NIOSH tests
and certifies respirators for use by workers to protect against workplace hazards.
Respirators certified by NIOSH will be labeled "NIOSH Approved" and will have an
approval label that identifies the hazard it will protect against. The N-95 respirator is
approved only for particulates including dust in the air from sweeping, sawing, mold
removal, and other activities that cause dust. The N-95 respirator is not designed to
protect against exposure to vapors or gases (e.g., carbon monoxide) and will not
provide protection from them.
A properly worn disposable respirator requires that:
Metal nose piece, if present, is on the top to adjust the fit to the wearer's nose.
NIOSH label is on the bottom outside of the respirator.
Both respirator retaining straps are in place, and they are securing the respirator to
the face (some respirators have only one strap).
For the Public Not Involved in Clean-up, Debris Removal, or Similar Activities
Persons not involved in activities that disturb mold-contaminated materials have a lower
risk for inhalation exposure relative to persons performing those types of activities.
Persons collecting belongings, visually inspecting homes or buildings, or doing basic
clean-up for short periods in a previously flooded home or building will not usually need
to use a respirator.
For the Public Unable to Use PPE or at High Health Risk from Exposure to Mold
The effect of exposure to mold varies widely. Persons who might be affected to a
greater extent than the majority of healthy adults include (5,6,9):
persons with respiratory conditions (e.g., asthma) or allergies, and
persons with weakened immune systems (e.g., patients receiving chemotherapy,
organ or bone marrow transplant recipients, or persons with human immunodeficiency
virus infection or autoimmune diseases).
Persons with special health concerns should consult their health-care provider if they
are concerned about mold exposure. Symptoms that might seem related to mold
exposure might have other causes, such as bacterial or viral infections or other
allergies. The level of risk associated with exposure activities and the potential benefit of
recommended PPE are unknown for pregnant women, persons aged >65 years, and
children aged <12 years; exposure-reducing behavior and respiratory protection might
be difficult for children aged <12 years.
Using respirators or other PPE might increase health risks for persons with underlying
health conditions. Persons who have trouble breathing while using a respirator should
stop working and contact a doctor or other medical provider (1).
For persons at potentially increased health risks from exposure to mold, persons of
unknown or uncertain risk, or persons unable to use respirators, caution is
recommended when entering heavily mold contaminated environments, particularly
when mold clean-up is occurring. Persons in these categories should avoid such
situations if possible.
Potential Health Effects of Fungal Contamination
In recent years, the health effects of exposure to mold in built environments have been
a subject of intense public concern. These concerns and how they are approached will
have important implications for the reconstruction and rehabilitation of cities in states
affected by major hurricanes or floods.
Many clinical conditions could be caused by the fungal contamination associated with
flooding after major hurricanes or floods. Predicting what might occur is speculative.
However, many of these conditions are uncommon and will be recognized only if there
is a high clinical index of suspicion (Table 2). Anticipating what medical problems could
be associated with post-flood fungal contamination might help in preventing them by
identifying susceptible populations and making recommendations for reducing
potentially harmful exposures.
Although this report focuses on potential health effects of fungal contamination, other
exposures are also of concern. For example, dampness favors proliferation of dust
mites and microorganisms such as bacteria (44,45) and nontuberculous mycobacteria
(46). Endotoxins (components of the cell walls of Gram-negative bacteria) have strong
inflammatory properties (6,44,45,47--49). Moisture also can release chemical
constituents from building materials (6). Standing water supports rodent and cockroach
infestations (15,44,45) and proliferation of mosquitoes (30). Fecal contamination of the
environment raises concerns about protozoal and helminthic parasites (50). Fungi are
not the sole potential cause of many conditions discussed in this report, and these
conditions are only a subset of the conditions of concern to clinicians and public health
professionals dealing with the aftermath of major hurricanes or floods (51).
Overview of Fungal-Induced Diseases
Fungi can cause a variety of infectious (52--58) and noninfectious conditions
(6,44,45,47,59,60). Several basic mechanisms can underlie these conditions, including
immunologic (e.g., IgE-mediated allergic), infectious, and toxic (6). Several of these
mechanisms contribute to pathogenesis of a fungal-induced disease. The types and
severity of symptoms and diseases related to mold exposure depend in part on the
extent of the mold present, the extent of the person's exposure, and the susceptibility of
the person (e.g., persons who have allergic conditions or who are immunosuppressed
are more susceptible than those without such conditions). Molds produce a variety of
volatile organic compounds (6,7,60), the most common being ethanol (61), which are
responsible for the musty odors associated with fungal growth. Exposure to moldy
indoor environments is also associated with a variety of upper and lower respiratory
tract symptoms (6).
Institute of Medicine Report on Damp Indoor Spaces and Health
In recent years, the issue of how damp indoor spaces and mold contamination affect
human health has been highly controversial. In response, CDC commissioned the
Institute of Medicine (IOM) to perform a comprehensive review of the scientific literature
in this area. The resulting report (6) was published in 2004 and remains the most
current and authoritative source of information on this subject. The IOM categorized its
findings into four categories:
sufficient evidence of a causal relation,
sufficient evidence of an association,
limited or suggestive evidence of an association, and
inadequate or insufficient evidence to determine whether an association exists.
"Inadequate or insufficient evidence to determine whether an association exists" does
not rule out the possibility of an association. Rather, it indicates that no studies
examined the relation or that published study results were of insufficient quality,
consistency, or statistical power to permit a conclusion about an association. No
conditions exists for which the IOM found sufficient evidence of a causal relation with
mold or with damp indoor spaces. Several of the conditions are of particular interest to
those engaged in the response to major hurricanes or floods (Table 3). Sufficient
evidence links upper respiratory tract symptoms (e.g., nasal congestion, sneezing,
runny or itchy nose, and throat irritation) to damp indoor environments and mold (with
exposure to mold often determined by self-report). Similarly, sufficient evidence exists
for a link with the lower respiratory tract symptoms of cough and wheeze. Sufficient
evidence also was found for a link between damp indoor environments, mold, and
asthma symptoms in sensitized persons with asthma. Evidence also is sufficient for an
association between mold exposure and hypersensitivity pneumonitis in a small
proportion of susceptible persons, invasive respiratory and other fungal infections in
severely immunocompromised persons, and fungal colonization of the respiratory tract
or infection in persons with chronic pulmonary disorders.
IgE-Mediated Diseases Caused by Fungi
IgE-mediated, or allergic, responses underlie the most common types of diseases
associated with exposure to fungi (6,45,47,48,49). Atopy, or the genetic predisposition
to form IgE responses to aeroallergens, is an important risk factor (45,47,48,49). Clinical
conditions associated with allergies include allergic rhinitis and asthma (6,45,47,48,49).
Allergic rhinitis is often associated with allergic conjunctivitis and sinusitis (45,47,49).
Symptoms of allergic rhinitis include sneezing; itching of the nose, eyes, mouth, or
throat; nasal stuffiness; clear rhinorrhea; and, if associated with allergic conjunctivitis,
red, itchy eyes. If associated with sinusitis, persons also might complain of sinus
fullness or postnasal drip, often purulent (47--49). Signs on physical examination
include pale, boggy nasal mucosa; nasal obstruction; and conjunctival redness.
Examination of nasal scrapings or secretions indicates eosinophilic inflammation (47-49). If appropriate allergy prick skin testing reagents or in vitro tests for serum specific
IgE are conducted, they demonstrate specific IgE-sensitization to causative allergens
(45,47--49). Skin testing reagents and blood tests documenting IgE-sensitization to
molds are, with few exceptions, poorly standardized and of unclear sensitivity and
specificity (45). The conventional hierarchy of treatment is avoidance of exposure to
inciting agents; pharmacotherapy with antihistamines, decongestants, or antiinflammatory agents (e.g., nasal steroid sprays); or, as a last resort, allergen
immunotherapy (47--49). Immunotherapy with fungal allergenic extracts is, with a few
exceptions, of unknown efficacy (47).
Asthma is a disease characterized by episodic, reversible airways obstruction and
eosinophilic airways inflammation (45,47--49,62,63). Over time, chronic asthma can
lead to airways remodeling and irreversible airways obstruction (45,47--49,62,63).
Persons with asthma often have symptoms such as chest tightness, wheezing,
dyspnea, or cough (45,47--49,62,63). Physical examination during active asthma might
indicate wheezing, but results of examinations between attacks are most often normal
(62,63). If performed during an active asthma attack, spirometry most often indicates
obstruction that reverses with inhalation of a bronchodilator (62,63). Persons with
asthma generally exhibit bronchial hyperreactivity to methacholine challenge (45,47-49,62). However, a small proportion of persons without asthma and a substantial
proportion of persons with airway disorders, including chronic obstructive pulmonary
disease (COPD), also might exhibit hyperreactivity to inhaled methacholine (49);
therefore, test results must be considered together with other clinical information (47-49,62,63). Approaches to demonstrating specific IgE sensitization to molds and
limitations of available methods are as described for allergic rhinitis (45,47--49). Asthma
is associated with airways inflammation that can be demonstrated by examining
induced sputum for eosinophils or measuring exhaled nitric oxide (47), but these tests
are often not performed in clinical settings.
Comprehensive guidelines for the staging and treatment of asthma are provided by the
National Institutes of Health (62,63). Identifying and avoiding triggers, including
occupational triggers, is a critical element of treatment. It is important to identify persons
with asthma triggered by materials in flood-damaged areas so avoidance measures can
be taken. Drug treatment of asthma consists of symptom controllers such as
bronchodilators and anti-inflammatory agents (e.g., corticosteroids or leukotriene
antagonists) (47--49,62,63). The role of allergen immunotherapy with most fungal
agents in treatment of asthma is unclear (48). Therapy with monoclonal anti-IgE is a
recently developed treatment option that can be used in carefully selected patients
when other, less expensive modalities fail to reduce dependence on systemic
corticosteroids (63). The exacerbation of symptoms of asthma is consistently associated
with damp buildings (6). If persons with asthma must engage in activities within damp or
mold contaminated buildings, their asthma should be well controlled before entering
these buildings, and those around them should be aware of the signs of asthma
symptoms. The onset of symptoms while in damp moldy environments, especially while
wearing PPE, should be an indication to leave the area and to seek appropriate medical
Allergic Diseases Associated With Airways Colonization
Allergic bronchopulmonary aspergillosis (ABPA) is a disease that can occur when the
airways of persons with obstructive pulmonary diseases (e.g., asthma or cystic fibrosis)
become colonized with Aspergillus fumigatus or other Aspergillus species (6,17,45,47-49). Inflammatory responses lead to additional airways damage. Marked worsening of
existing asthma is a typical presentation of ABPA. Symptoms include recurrent
episodes of bronchial obstruction, fever, malaise, expectoration of brownish plugs,
peripheral blood eosinophilia, hemoptysis, and sometimes asymptomatic pulmonary
consolidation. Other features include immediate skin test reactivity to Aspergillus spp.
antigens, precipitating serum antibodies to A. fumigatus, markedly elevated serum total
IgE, fleeting lung infiltrates, and central bronchiectasis (45,47--49). Criteria for diagnosis
have been published (45,47--49). Airways colonization with other fungal species can
result in a similar clinical picture. Although no known relation exists between levels of
exposure to Aspergillus spp. and development of ABPA, clinicians should suspect and
evaluate for the condition when appropriate.
Allergic fungal sinusitis (AFS) is typically noninvasive and occurs in allergic,
immunocompetent patients (6,45,47--49): most have asthma, and 85% have nasal
polyps (47). Invasive fungal sinusitis can occur in patients who are
immunocompromised with illnesses such as diabetes, hematologic malignancies or
immunosuppressive treatments or chronic steroid therapy (6,47). Fungal colonization is
associated with a characteristic allergic mucin containing high levels of eosinophils
(6,45,47--49). The mere presence of fungi in the nasal passages is not indicative of an
active infection.
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, is a
granulomatous interstitial lung disease (6,17,45,47--49). A wide range of materials,
including fungi, can be inhaled and thus sensitize susceptible persons by inducing both
antibody and cell-mediated immune responses (6,17,45,47--49). Re-exposure of
sensitized persons leads to lung inflammation and disease (6,17,45,47--49). Buildingrelated HP caused by fungi and bacteria has been well documented (6,17). Usually,
only a small fraction of those with a given exposure develop HP; therefore, poorly
understood host factors play an important role in disease pathogenesis (6,47--49).
The presentation of HP is complex and can be either acute, subacute, or chronic
(6,47,48). The acute form is often associated with heavy exposures and characterized
by chills, fever, malaise, cough, and dyspnea appearing 4--8 hours after exposure
(6,47,48) and is often confused with pneumonia. The chronic form is thought to be
induced by continuous low-level exposure. Onset generally occurs without chills, fever,
or malaise and is characterized by progressive shortness of breath with weight loss
(47,48). Chronic HP can be confused with idiopathic pulmonary fibrosis or other forms
of interstitial lung disease (47,48).
The diagnosis of HP, especially the chronic form or when presentation is mild, is often
missed early in the course of the disease. If it does occur in the aftermath of major
hurricanes or floods, a high degree of clinical suspicion is required for detection. In
general, when HP is suspected, a clinical and exposure history should be performed.
Patients should be asked about their possible exposure to damp and water-damaged
areas, farms, birds, hot tubs, and other environments that might cause HP.
Environmental sampling for the presence of microorganisms known to cause HP and
serologic testing for circulating precipitins can help to establish causative exposures
(47--49). Chest imaging using chest radiographs or high-resolution computed
tomography scanning of the thorax, lung-function tests, broncholaveolar lavage, and
lung biopsy all have roles in diagnosis (47--49). Although established criteria exist for
the diagnosis of hypersensitivity pneumonitis (64,65), in the setting of a documented
post-disaster HP outbreak, a noninvasive approach to identifying cases could be more
appropriate and cost-effective than requiring conventional diagnostic testing. A recent,
large multicenter study indicated that under conditions of low or high prevalence, six
predictors could be used in combination for noninvasive diagnosis of HP (66):
exposure to a known offending antigen,
positive precipitating antibodies to the offending antigen,
recurrent episodes of symptoms,
inspiratory crackles on physical examination,
symptoms occurring 4--8 hours after exposure, and
weight loss.
Optimal treatment is elimination of causative exposures. The IOM report (6) provides
information about management of building-related HP that is relevant to reoccupation of
structures contaminated by fungi after major hurricanes or floods. Such management
includes giving standard medical therapy (e.g., systemic corticosteroids and removing
sources of fungal contamination from the environment). In some cases, if efforts to
remove mold from a building are unsuccessful in relieving symptoms, the patient might
need to move to another home or office.
Inhalation Fevers
Inhalation fever is a general name given to a variety of influenza-like, self-limited
syndromes that might be caused by a variety of stimuli. Two types of inhalation fevers
are of potential concern after major hurricanes or floods.
Humidifier fever is characterized by fever, respiratory symptoms, and fatigue with onset
within hours after exposure to contaminated humidification systems (6,17,45,47).
Obtaining a supportive history is critical to diagnosis. Thermophilic actinomycetes; other
bacteria, including species of Legionella and Pseudomonas; and protozoa have been
associated with humidifier fever (17). Aerosolized endotoxin derived from Gramnegative bacteria has an important role in this condition (17,47). Although humidifier
fever can be confused with acute HP, it is a short-term ailment and removal from
exposure is effective treatment (17,47). Humidifier fever is thought to represent a
nonspecific inflammatory response to exposure (17,47).
Organic dust toxic syndrome (ODTS) has been reported among workers in a variety of
agricultural and industrial settings and is thought to involve inhalation exposure to
materials with heavy microbial contamination (67--69). Etiologic exposures that cause
ODTS are often a poorly defined mixture of substances, including fungi, bacteria, and
microbial constituents such as endotoxin (67--69). ODTS is characterized by fever and
influenza-like symptoms, including general weakness, headache, chills, body aches,
and cough occurring 4--12 hours after heavy exposure to organic dust (67--69).
Dyspnea also is sometimes present. Results of chest auscultation and chest
radiographs are usually normal (67,68). The peripheral white blood count is often
elevated during attacks. Accurate patient history is critical for making a correct
diagnosis. Although the symptoms resemble those of acute HP, they are not caused by
response of the immune system to a specific antigen in the environment (67,68). ODTS
poses a risk for workers performing renovation work on building materials and is a
realistic concern for workers handling heavily contaminated materials in the aftermath of
major hurricanes or floods. ODTS is best prevented by minimizing exposure through
engineering controls, administrative controls, and respirators (69). For agricultural
workers handling organic dusts, CDC recommends using the most practical respirator
with the highest assigned protection factor.
Toxic Effects of Fungi
Certain common molds can produce metabolites with a wide range of toxic activities
such as antibiotic (e.g., penicillium), immune-suppressive (e.g., cyclosporine),
carcinogenic (e.g., aflatoxins), emetic, and hallucinogenic (e.g., ergot alkaloids)
(6,11,17,59). Mycotoxins are fungal metabolites that poison humans and animals.
Although ingestion is the most common route of exposure, inhalation and dermal
contact also are exposures of concern (6,11,17,59). Mycotoxin production is dependent
not only on species and strain of mold, but also on environmental conditions (e.g.,
temperature, water activity, light) and growth substrate (11,17). Thus, the presence of
toxin-producing mold species does not necessarily indicate whether mycotoxins are
Mycotoxins were prematurely proposed as the cause of a disease outbreak of eight
cases of acute pulmonary hemorrhage/hemosiderosis in infants in Cleveland, Ohio, in
1993 and 1994 (70). The cluster was attributed to exposure to mycotoxins produced by
Stachybotrys chartarum. Subsequent reviews of the evidence concluded that insufficient
information existed and no such association was proven (71).
Almost all of the known effects of mycotoxin exposures are attributable to ingestion of
contaminated food (72). Health effects from inhalational exposures to toxins are not well
documented. IOM found inadequate or insufficient evidence for a link between exposure
to damp indoor environments and molds with a variety of conditions that have been
attributed to toxicity (6) (Table 3). Certain case studies of agricultural and remediation
workers have described adverse health effects such as skin irritation, skin necrosis,
cough, rhinitis, and bloody nasal exudate after inhaling or touching materials with heavy
fungal contamination (73--76). Whether these effects resulted from exposure to
mycotoxins or from a general overload of organic material is unknown. No commercial
clinical diagnostic tools are available to determine whether a person's health effect is
related to exposure to mycotoxins. Because of the lack of information about
noningestion mycotoxin exposure and adverse health effects in humans, precautions
should be taken when handling heavily contaminated building materials.
Fungal Infections
No reports of increased fungal infections related to floods in the United States exist.
However, anecdotal case reports of fungal infection after floods include
Apophysomyces elegans wound infection in a man who sustained traumatic injuries
after the southeast Asian tsunami in December 2004 (77). A. elegans belongs to the
Zygomycetes class of fungi. Infections are most commonly seen in
immunocompromised and diabetic patients, and rarely in immunocompetent persons.
The cause of infection in immunocompetent persons is usually cutaneous trauma with
direct implantation of fungal organisms into the wound from soil contamination (78).
Theoretically, infection with fungal species that contaminate buildings, building
constituents, and the environment after major hurricanes or floods is a potential
concern. In general, persons with impaired host defenses (especially if impaired
because of cell-mediated immunity or neutropenia) suffer the most severe types of
fungal infections (6,52,53) (Table 4). However, invasive fungal infections also can occur
in persons with normal host defenses and, in certain situations, can be life threatening
(52,53) (Table 5). Persons at greatest risk for invasive fungal infection from heavy
fungal contamination after major hurricanes or floods are those with impaired host
defenses (6,52,53) (Table 4). Any impairment in cell-mediated immunity or neutropenia
(e.g., human immunodeficiency virus [HIV] infection, leukemia, lymphoma, and diabetes
mellitus) increases risk for many types of invasive fungal infections (52,53). Severely
immunosuppressed persons, such as solid-organ or stem-cell transplant recipients or
those receiving cancer chemotherapy agents, corticosteroids, or other agents inhibiting
immune function, are at much higher risk for locally invasive infections of the lungs,
sinuses, or skin and systemic infections (52,53). Aspergillus spp., zygomycetes, and
Fusarium spp. are particularly important problems (52,53,56). These serious infections
are often fatal, even with aggressive antifungal therapy (52,53,56).
Protective measures, such as HEPA filtration, implemented during periods of extreme
susceptibility to invasive fungal infections are well established and effective in hospitals
(79). However, preventive measures outside the hospital are less well established.
Current guidelines emphasize the importance of avoiding areas of high dust (e.g.,
excavation sites, building construction or renovation sites, chicken coops, and caves)
and factors associated with fungal infections (e.g., foods that increase a person's risk for
fungal exposure) (80).
Obstructive pulmonary diseases such as asthma, cystic fibrosis, and COPD, might
predispose persons to airway colonization with Aspergillus spp. (6,17,45,47--49).
Inflammatory host responses to colonization can lead to ABPA (6,17,45,47--49,52).
Aspergillus spp. also can cause invasive or semi-invasive infection in persons with
COPD, especially in those being treated with corticosteroids. Chronic necrotizing
pulmonary aspergillosis is an indolent condition observed in persons with underlying
lung disease (53).
Colonization of lung cavities (e.g., tuberculosis cavities or emphysematous blebs) by
Aspergillus spp. can cause pulmonary aspergillomas (fungus balls) (6,52), which are
conglomerations of Aspergillus spp. hyphae matted together with fibrin, mucus, and
cellular debris. These often do not cause symptoms, but they can be associated with
hemoptysis (52,53). An exposure-response relation has never been established linking
levels of exposure to Aspergillus spp. with development of any of these conditions.
Therefore, to what degree exposure to fungal contamination after major hurricanes or
floods would increase any risk is unclear. However, despite unknown benefit, persons
with clinically significant obstructive pulmonary diseases (e.g., asthma, cystic fibrosis,
COPD), and persons with cavitary lung disease from conditions such as tuberculosis
should avoid airborne exposure to materials that have become heavily contaminated
with fungal growth in the wake of major hurricanes or floods.
Persons with normal host defenses also are subject to fungal infections (52,53) (Table
5), and persons with impaired host defenses can acquire any of these, often with
greater severity. Ocular, skin, and superficial infections occur in those with normal host
defenses and range from the relatively common (e.g., ringworm, athlete's foot) to the
relatively rare (e.g., sporotrichosis) (52,53). Of particular relevance in areas with fungal
contamination after major hurricanes or floods are organisms that cause localized skin
and superficial infections following traumatic inoculation with soil and plant saprophytes,
which are found in air, soil, and plant materials. For example, Scedosporium
apiospermum (Pseudallescheria boydii) can be recovered from polluted water, sewage,
swamps, and poultry or cattle manure (52,53,55,58). Although rare in the United States,
this organism can cause a soft tissue infection called Madura foot, a mycetoma in which
the draining sinuses show white grains containing fungal elements. This organism also
can produce septic arthritis or osteomyelitis after penetrating trauma. Sporothrix
schenckii is a dimorphic fungus that produces soft tissue infections after traumatic
inoculation from a contaminated environmental source (52,53), such as sphagnum
moss, roses, plant seedlings, and other vegetation. Lymphocutaneous lesions are the
hallmark of sporotrichosis, as the organisms spread through the local lymphatics after
primary inoculation. A high degree of clinical suspicion is needed to diagnose the less
common, locally invasive fungal infections. Diagnosis is made by histopathology and
culture after biopsy of the affected lesion. Histopathology must be performed to verify
that a recovered isolate is the cause of disease and not an environmental contaminant.
Culture must be performed to identify the agent correctly. Fungal isolates are identified
in a clinical mycology laboratory.
Exposures that result in invasive pulmonary mycoses in persons with normal host
defenses are generally thought to occur outdoors where active disturbance of a
reservoir has occurred (52,53). The mode of transmission is inhalation of fungal spores.
Person-to-person transmission of pulmonary mycoses does not occur (53). Diseases
relevant to flood prone areas such as the Gulf Coast states include histoplasmosis and
blastomycosis. Histoplasmosis is unlikely to be increased as a result of fungal
contamination after major hurricanes or floods. The condition is caused by Histoplasma
capsulatum, a dimorphic fungus found in soil enriched with the droppings of birds and
bats (52,53). Areas with endemic disease in the United States include the Mississippi
and Ohio River valleys, but cases have occurred in other parts of the United States.
Many persons develop no symptoms when exposed to H. capsulatum in an endemic
Blastomycosis is a potential problem after major hurricanes or floods in areas with
endemic disease because it can cause serious disease even in those with normal host
defenses (52,53). Blastomycosis is caused by the dimorphic fungus Blastomyces
dermatitidis (52,53). The organism is found in moist soil, frequently along streams or
rivers enriched with decaying vegetation. In the United States, the organism is most
commonly found in states surrounding the Mississippi and Ohio rivers (52,53). An area
in Louisiana about 70 miles from New Orleans has endemic blastomycosis (81). In
Louisiana, cases occur at an incidence of about 1--10 per year, mostly in the area of
Washington Parish where the condition is endemic (81). Outbreaks have been
associated with manipulation of decaying vegetation or recreational activity near lakes
or rivers (53). The incubation period is not certain but, on the basis of data from
outbreaks, appears to be about 45 days (82), ranging from weeks to months.
The clinical spectrum of blastomycosis includes asymptomatic infection, acute or
chronic pneumonia, and disseminated disease (52,53). Pulmonary infection can mimic
acute bacterial pneumonia or tuberculosis with progression to acute respiratory distress
syndrome. Alveolar infiltrates, mass lesions that mimic bronchogenic carcinoma, and
fibronodular interstitial infiltrates are the most common radiographic findings (52,53).
Disseminated blastomycosis often appears as ulcerative skin lesions with multiple
necrotic bone lesions in the vertebrae, skull, or long bones (52,53).
Culture of lesions or histopathologic evidence from infected tissue is required for
diagnosis of blastomycosis (52,53). Direct microscopy of pus, scrapings from skin
lesions, or sputum showing thick-walled broad-based budding yeast cells 5--15 µm in
diameter supports a presumptive diagnosis of blastomycosis and might, in the
appropriate clinical setting, prompt the initiation of antifungal therapy (52,53). Serologic
tests can be performed on serum from patients showing signs of suspected pulmonary
blastomycosis or with suggestive skin lesions. A positive immunodiffusion (ID) test,
showing a precipitin band with the Blastomyces A antigen, is highly specific for the
disease and does not require paired serum samples (52,53). However, the sensitivity is
poor (33%--88%), so a negative ID test does not rule out the disease (52,53). For cases
with negative results, the test should be repeated in 3--4 weeks after the initial
sampling. The complement fixation (CF) test for blastomycosis has poor sensitivity and
Fungal brain abscesses are uncommon in healthy persons (52,53,57). The primary
infection results from inhalation of infectious conidia from the environment; the route of
infection appears to be hematogenous dissemination from the lungs (52,53,57). Of
particular interest after major hurricanes or floods is S. apiospermum (P. boydii)
(52,53,57). Many case reports document patients with focal neurologic defects caused
by multiple brain abscesses weeks or months after nearly drowning. The organism
apparently spreads hematogenously after initial aspiration of sewage-laden water (from
floods, lagoons, or bayous) into the lungs. Near drowning presumptively results in a
massive inoculation of mold into the lungs.
Preventing Adverse Health Effects From Environmental Fungal Contamination
After Major Hurricanes or Floods
Persons should reduce their exposure to molds as much as possible (with the
realization that fungi are ubiquitous). Persons with underlying or induced
immunosuppressed conditions or diseases caused by immune sensitization to fungal
constituents present in mold growth should be especially careful to reduce exposure. If
exposure to heavily mold-contaminated materials is unavoidable, persons should use
appropriate administrative, engineering, and personal protection controls. Because a
person's likelihood of developing adverse health effects from mold exposure depends
on the type of exposure and on individual susceptibility, precautionary measures need
to be customized. Recommended measures are based on professional judgment
because of lack of available scientific evidence. For example, no research studies have
evaluated the effectiveness of personal protective equipment in preventing illness from
mold exposure. Total avoidance of heavily contaminated buildings or other high
exposure situations is suggested for persons with specific underlying conditions such as
profound immunosuppression. Respiratory protection, dermal protection, and occlusive
eye protection recommendations are customized to various populations and exposureassociated activities. Repeated or prolonged exposure probably poses a greater health
risk than do exposures of a similar intensity, but short duration. Preventive precautions
are especially important for persons who expect to be highly exposed for a long time.
Public Health Strategies and Recommendations for State and Local Officials
Recommendations from CDC are for protecting and monitoring the health and safety of
workers and residents who enter, repair, or destroy flooded buildings. The
recommendations are focused on limiting human exposure to mold and other microbial
agents and preventing any adverse health effects related to such exposure. Several
factors are assumed:
In the aftermath of major hurricanes and floods, buildings or materials soaked for >48
hours are contaminated with mold unless proven otherwise by inspection or adequate
environmental sampling or cleaned according to the EPAs recommendations (13).
Workers and residents might be exposed to high levels of mold-related contaminants.
Sufficient evidence exists of an association between adverse health outcomes and
exposure to damp indoor environments or materials contaminated with fungal growth.
Insufficient evidence exists for establishing health-related guidelines on the basis of
concentrations of mold (quantitative measure) or species of mold (qualitative measure)
in either indoor or outdoor environments.
Allergen testing to determine the presence of IgE to specific fungi might be a useful
component in the complete clinical evaluation and diagnosis of mold-related allergies
and in the decision to avoid exposure to fungal allergens that might be causing allergic
symptoms. However, testing for IgE sensitization to molds has important limitations.
Allergens used in these tests are often poorly standardized and the tests often have
unclear sensitivity and specificity. In addition, allergen testing is not relevant to diseases
that are not mediated by IgE.
Clear, concise, and practical recommendations and actions are necessary to limit
exposure to mold and to prevent mold-related health outcomes where possible.
Assessing Exposure to Mold
Exposure assessment is usually a critical step in determining whether persons are
exposed to a hazard at a level that could have an adverse health effect. The mere
presence of a chemical or biologic hazard in the environment is insufficient to create a
public health hazard. The contaminant must be present in an environmental medium
(e.g. air, water, food, and dust) that allows it to come in contact with persons and move
along a biologic pathway (e.g., inhalation, ingestion, and absorption). In addition, the
concentration of the contaminant must be sufficient to create a biologic response that
leads to an adverse health outcome. Mold and its spores exist in damp materials.
Disturbing mold releases potentially hazardous particulates into the air, which can then
be drawn into the sinuses and lungs. Although molds also might directly attack the skin
or openings in the skin, the most common route of exposure is through the air and into
the body by inhalation. Environmental sampling for molds has limited value and, in most
instances, is not needed after major hurricanes or floods.
Exposure Assessment
Building interiors should be assumed to be substantially contaminated with mold in the
following circumstances:
The building was saturated with water for >48 hours.
Visible mold growth is extensive and in excess of that present before a major
hurricane or flood
Signs of water damage are visible or mildew odors are strong.
Exposure to materials and structures contaminated with mold should be assumed to
present a potential health risk regardless of the type of mold. Risk for illness does not
necessarily vary with the type of mold or the extent of contamination.
Preventing Excessive Exposure to Mold
Preventing excessive exposure to mold is the best way to avoid harmful health
consequences. The preferred approach to preventing mold exposure is to prevent water
from infiltrating a building or damaging household goods and structures. After major
hurricanes or floods, substantial water damage and mold growth might occur in many
If left undisturbed, mold is generally not a hazard, and most persons will not be
adversely affected by moderate exposure to mold. However, in the aftermath of a major
hurricane or flood, remediation activities within buildings will disturb any mold that is
growing and lead to exposure. To prevent excessive exposure to mold in contaminated
areas that are disturbed, persons who enter those areas should implement
environmental controls (e.g., suppression of dust and isolation of the contaminated
area), use PPE, or both. Preventing human exposure to mold and health effects from
such exposure depends on three factors:
The likely concentration of mold in or on the building fabric or materials.
The duration and type of activity undertaken in the mold-contaminated area.
The susceptibility of the person entering the area to the various health effects.
Four methods for preventing exposure to mold can be used in combination:
avoiding areas thought to be mold-contaminated,
using environmental controls,
using PPE, and
employing strict personal hygiene.
The following persons should avoid mold-contaminated environments entirely:
transplant recipients, including those who received organ or hematopoietic stem cell
transplants during the preceding 6 months or who are undergoing periods of substantial
persons with neutropenia (neutrophil count <500/µL) attributed to any cause,
including neoplasm, cancer chemotherapy, or other immunosuppressive therapy,
persons with CD4+ lymphocyte counts <200/µL attributed to any cause, including HIV
infection, and
other persons considered by their physicians to have profoundly impaired antifungal
host defenses caused by congenital or acquired immunodeficiency.
The following persons might be able to tolerate limited exposure, but they should
consult with their physicians and should consider avoiding areas where moldy materials
are disturbed:
persons receiving chemotherapy for cancer, corticosteroid therapy, or other
immunosuppressive drug therapy, as long as neutropenia or CD4+ lymphopenia are not
persons with immunosuppressive diseases such as leukemia, lymphoma or HIV
infection, as long as there is not marked impairment in immune function,
pregnant women,
persons aged >65 years,
children aged <12 years, particularly infants, and
persons with chronic, obstructive, or allergic lung diseases.
All buildings with extensive mold contamination require remediation before
rehabilitation. Remediation includes structural repairs to prevent additional water
intrusion, removal of mold-contaminated materials that cannot be adequately cleaned
and decontaminated, and cleaning and decontamination of mold-contaminated
materials that can withstand such treatment. Health-care facilities and other locations
that house highly susceptible persons require special attention. These facilities must be
adequately remediated before being occupied by highly susceptible persons. Guidelines
for remediating health-care facilities include:
Remediation and Infection Control Considerations for Reopening Healthcare
Facilities Closed due to Extensive Water and Wind Damage (83), and
Check List for Infection Control Concerns when Reopening Healthcare Facilities
Closed due to Extensive Water and Wind Damage (84).
Use of Environmental Controls
Examples of environmental controls include isolation or containment of the
contaminated area, ventilation of the area, and suppression of dust in the area (e.g., by
wet-mopping the mold-contaminated surfaces to reduce airborne mold concentrations).
Certain methods of isolation can be used to minimize mold exposure. For example,
workers operating heavy equipment during the demolition and removal of moldcontaminated materials can be isolated in sealed, positive-pressure, air-conditioned
cabs that contain filtered air recirculation units. Another method of isolation is sealing off
of mold-remediation areas in occupied, mold-contaminated buildings. However, such
isolated areas must also be adequately ventilated.
Preventing the creation of dust and limiting exposure to dust are essential to minimizing
exposure to mold. When cleaning up dust, workers should use wet mops or vacuums
with HEPA filters instead of dry sweeping.
Use of PPE
Inhalation is the primary exposure route of concern related to mold for workers,
homeowners, and building occupants. Environmental controls are sometimes
inadequate to control airborne exposure to mold or dust containing mold. In such cases,
respirators protect persons from inhaling airborne contaminated dust and other
particulates released during dust-generating processes (e.g., clean-up or debris
removal). Recommendations on when to wear a respirator depend on the severity of
mold contamination, whether the person's activity is such that mold or particles
containing endotoxin or other microbial agents are likely to be released into the air, and
the person's health status (Table 1).
The following recommendations are made with the assumption that extensive mold
contamination is present.
Respiratory Protection
Recommendations for use of respirators in include:
Healthy persons who are in a building for a short time or who are in a place where
activity minimally disturbs contaminated material might not need a respirator (Table 1).
Persons engaged in activities that moderately disturb contaminated material (e.g.,
light cleaning by removing mold from surfaces with a wet mop or cloth) and persons
with health conditions that place them at risk for mold-related health problems should
use at least an N-95 respirator that is certified by NIOSH.
Persons doing remediation work that involves extensive exposure to mold should
have respiratory protection greater than that provided by a NIOSH-certified N-95
respirator. Full face-piece respirators that have NIOSH-certified N100, R100, P100
particulate filters are recommended. For powered air-purifying respirators, a HEPA filter
is recommended.
--- Respirator selection is made after considering the characteristics of the work
activities; the specific exposures of concern; and the protection factors, advantages,
and disadvantages of various respirators.
--- The determination of whether a person will have extensive exposure to mold
should be based on several factors, including the size of the mold-contaminated area,
the type of mold-contaminated material, and the activities being performed. Guidelines
based solely on area of contamination define extensive contamination as being >100
square feet.
--- Formal fit testing is recommended for anyone engaging in remediation work
causing extensive exposure to mold.
Guidelines for respiratory protection use:
Respirators must fit well and be worn correctly.
NIOSH tests and certifies respirators for use by workers to protect against workplace
hazards. Respirators certified by NIOSH have "NIOSH Approved" written on them and
have a label that identifies the hazard the respirators protect against.
The N-95 respirator is approved only as protection against particulates (including
dust) and will not protect persons from vapors or gases such as carbon monoxide.
Eye Protection and Protective Clothing
Eye protection is warranted for workers cleaning up mold-contaminated areas and for
persons with health conditions that place them at high health risk (Table 1). To protect
eyes, a full face-piece respirator or properly fitted goggles designed to prevent the entry
of dust and small particles should be used. Safety glasses or goggles with open vent
holes are not appropriate during mold remediation. The CDC/NIOSH publication Eye
Safety: Emergency Response and Disaster Recovery, provides further information on
this topic (35).
While conducting building inspections and remediation work, persons might encounter
hazardous biologic agents and chemical and physical hazards. Consequently,
appropriate personal protective clothing, either reusable or disposable, is recommended
to minimize cross-contamination between work areas and clean areas, to prevent the
transfer and spread of mold and other contaminants to street clothing, and to eliminate
skin contact with mold and chemicals. In hot climates, wearing protective clothing might
increase risk for dehydration or heat stress, and special precautions to avoid these
conditions (e.g., drink plenty of water) might be needed.
Disposable PPE should be discarded after it is used. Such equipment should be placed
into impermeable bags and usually can be discarded as ordinary construction waste.
Appropriate precautions and protective equipment for biocide applicators should be
selected on the basis of the product manufacturer's warnings and recommendations
(e.g., goggles or face shield, aprons or other protective clothing, gloves, and respiratory
protection). Reusable protective clothing should be cleaned according to the
manufacturers' recommendations after the product has been exposed to mold. Hands
should be washed with clean potable water and soap after gloves are removed.
General Distribution of PPE
Health officials should consider whether their agencies should supply PPE to residents
who might not otherwise be able to acquire the necessary equipment. Providing PPE to
the local population would require substantial resources and a mechanism for
distributing them.
Mold-Contaminated Areas
Items that have soaked up water and that cannot be cleaned and dried should be
removed from the area and discarded.
Dehumidifiers and fans blowing outwards towards open doors and windows can be
used to remove moisture.
Mold Removal
The procedure to remove mold from hard surfaces that do not soak up water (i.e.,
nonporous) is as follows:
Mix 1 cup of bleach in 1 gallon of water.
Wash the item with the bleach mixture.
Scrub rough surfaces with a stiff brush.
Rinse the item with clean water.
Dry the item, or leave it to dry.
Cleaning Hard Surfaces That Do Not Soak Up Water
The procedure to prevent mold growth on hard surfaces that do not soak up water is as
Wash the surfaces with soap and clean water.
Disinfect them with a mixture of 1 cup of bleach in 5 gallons of water.
Allow to air dry.
Additional Safety Guidelines for Mold Clean-up
Persons cleaning moldy or potentially moldy surfaces should:
Wear rubber boots, rubber gloves, and goggles when cleaning with bleach.
Open windows and doors to get fresh air.
Never mix bleach and ammonia because the fumes from the mixture can be fatal.
Health-Outcome Surveillance and Follow Up
State and local public health agencies do not generally collect information on the
conditions related to mold exposure. In situations where there are large numbers of
flooded and mold-contaminated buildings, such as occurred in New Orleans after
hurricanes Katrina and Rita in fall of 2005 (2), the repopulation of those once-flooded
areas probably will expose a large number of persons to potentially hazardous levels of
mold and other microbial agents.
Efforts to determine the health effects of these exposures and the effectiveness of
recommendations to prevent these adverse health effects require a surveillance
strategy. Developing such a strategy requires that federal and local health agencies
work together to monitor trends in the incidence or prevalence of mold-related
conditions throughout the recovery period.
Monitoring trends in health outcomes that might be related to mold exposure will require
substantial human and financial resources and will face several challenges. Health
outcomes that might be attributed to mold exposure fall into several broad categories.
Some potential health outcomes are rare, difficult to diagnose, and relatively specific for
fungal exposure (e.g., blastomycosis). Other health outcomes are relatively easy to
diagnose, but they have numerous etiologic factors and are difficult to attribute
specifically to mold exposure (e.g., asthma exacerbations). Tracking different health
outcomes that might be caused by mold exposure requires different surveillance
methods. In some cases, follow-up research will be needed to verify that surveillance
findings and health outcomes are the result of mold exposure. For some conditions,
difficulties in interpreting trends and in relating the outcome to mold exposure might
suggest that surveillance is not an appropriate public health approach.
Results of surveillance and follow-up activities will help CDC refine the guidelines for
exposure avoidance, personal protection, and clean-up. In addition, these activities
should assist health departments to identify unrecognized hazards.
Public health agencies should consider collecting health outcome information from
health-care facilities to monitor the incidence or prevalence of selected conditions. State
or local agencies should determine the feasibility of this approach and consider the
required resources available or attainable to accomplish this goal. Institutions from
which data could be collected include hospitals, emergency departments, clinics and,
for some outcomes, specific subspecialty providers. Surveillance will require the
establishment of case definitions and reporting sources; development of reporting
mechanisms; training of data providers; and the collection, analysis, and reporting of
data. The surveillance data should be used to identify increases in disease that are
substantial enough to trigger public health interventions or follow-up investigations to
learn the reason for the increase and establish targeted prevention strategies.
Public health agencies should consider the need for clinicians to report cases of known
or suspected mold-associated illnesses (e.g., invasive fungal disease, blastomycosis,
hypersensitivity pneumonitis attributed to mold contamination, ODTS attributed to
contaminated dust exposure, and alveolar hemorrhage in infants) to public health
authorities for tracking and follow-up investigations. Providers caring for patients at high
risk for poor health outcomes related to mold exposure could be targeted. For example,
hematologists, rheumatologists, and pulmonologists might care for many patients at risk
for invasive mold infections because of underlying malignancies and
immunosuppression. Enhancing provider-based surveillance requires targeting and
educating providers; developing reporting mechanisms; and collecting, analyzing, and
reporting data.
Public health agencies should consider the need for establishing laboratory-based
surveillance as an efficient method for monitoring mold-related illnesses that involve
laboratory analyses (e.g., invasive fungal disease, blastomycosis, invasive aspergillosis,
histoplasmosis, Aspergillus preceptins, zygomycosis, and fusariosis).
Clinical Care
Health-care providers should be alert for unusual mold-related diseases that might
occur (e.g., hypersensitivity pneumonitis, ODTS, and blastomycosis). Otherwise, such
diseases might not be recognized. Scientific evidence is insufficient to support the
routine clinical use of immunodiagnostic tests as a primary means of assessing
environmental fungal exposure or health effects related to fungal exposure. Health-care
providers who care for persons who are concerned about the relation between their
symptoms and exposure to fungi are advised to use immunodiagnostic test results with
care and only in combination with other clinical information, including history, physical
examination, and other laboratory data. If appropriate allergy prick skin testing reagents
or in vitro tests for serum specific IgE are available, they can be used to show specific
IgE-sensitization to causative allergens. Unfortunately, skin testing reagents and blood
tests documenting IgE-sensitization to molds are, with few exceptions, poorly
standardized and of unclear sensitivity and specificity. The conventional hierarchy of
treatment for allergic diseases includes avoidance of exposure to inciting agents,
pharmacotherapy and, as a last resort, allergen immunotherapy. Immunotherapy with
fungal allergenic extracts is, with a few exceptions, of unknown efficacy. Clinicians
should report cases of mold-induced illness to local health authorities to assist in
surveillance efforts.
Athena Gemella, MS, coordinated the external review of the document; Marissa Scalia,
MPH, and Allison Stock, PhD, provided background and resource materials for the
document, National Center for Environmental Health. Kay Kreiss, MD, provided input
and feedback during the development of the document, National Institute for
Occupational Safety and Health.
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[email protected]
Date last reviewed: 5/25/2006
Prepared by:
Mary Brandt, PhD,1 Clive Brown, MBBS,2 Joe Burkhart, MS,3 Nancy Burton, MPH,3
Jean Cox-Ganser, PhD,3 Scott Damon, MAIA,2 Henry Falk, MD,4 Scott Fridkin, MD,1
Paul Garbe, DVM,2 Mike McGeehin, PhD,2 Juliette Morgan, MD,1 Elena Page MD,3
Carol Rao, ScD,1,5 Stephen Redd, MD,2 Tom Sinks, PhD,2 Douglas Trout, MD,3
Kenneth Wallingford, MS,3 David Warnock, PhD,1 David Weissman, MD3
1National Center for Infectious Diseases
2National Center for Environmental Health
3National Institute for Occupational Safety and Health
4Coordinating Center for Environmental Health and Injury Prevention
5Office of Workforce and Career Development
The material in this report originated in the National Center for Environmental Health,
Agency for Toxic Substances Disease Registry, Howard Franklin, MD, Director, and the
Division of Environmental Hazards and Health Effects, Michael A. McGeehin, PhD,
Corresponding preparer: Clive Brown, MBBS, National Center for Environmental Health,
CDC, Century Center, Building 2400, MS E-39, Atlanta, GA 30329. Telephone: 404498-1000; Fax: 404-498-1088; E-mail: [email protected]
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