United States
Environmental Protection
August 1993
&EPA Flood Cleanup: Avoiding
Indoor Air Quality Problems
Fact Sheet
During a flood cleanup, the indoor air quality in
your home or office may appear to be the least of
your problems. However, failure to remove
contaminated materials and to reduce moisture and
humidity can present serious long-term health risks.
Standing water and wet materials are a breeding
ground for microorganisms, such as viruses, bacteria,
and mold. They can cause disease, trigger allergic
reactions, and continue to damage materials long
after the flood.
This fact sheet discusses problems caused by
microbial growth, as well as other potential effects of
flooding, on long-term indoor air quality and the
steps you can take to lessen these effects. Although
the information contained here emphasizes
residential flood cleanup, it is also applicable to other
types of buildings.
Prepare for Cleanup
Obtain a copy of the free booklet. Repairing Your
Flooded Home, from the Federal Emergency
Management Agency (FEMA) or your local chapter
of the American Red Cross (see listings at the end of
this fact sheet). Read that booklet carefidly before
cleanup because it discusses flood safety issues
and can save your life. The booklet also contains
detailed information on proper methods for cleaning
"up your home.
This fact sheet provides additional information,
not covered in the FEMA/American Red Cross
booklet, on indoor air quality concerns related to -
flooding. Many of the methods used for general
cleanup, as detailed in the booklet, are the same as
those used to avoid problems with indoor air quality.
For brevity, we have not provided detail on the
general methods used for cleanup here. This fact
sheet is intended to be used in conjunction with
the FEMA/American Red Cross booklet
Avoid Problems from Microbial Growth
Remove Standing Water
Standing water is a breeding ground for
microorganisms, which can become airborne and be
inhaled. Where floodwater contains; sewage or
decaying animal carcasses, infectious disease is of
concern. Even when flooding is due to rainwater,
the growth of microorganisms can cause allergic
reactions in sensitive individuals. For these health
reasons, and to lessen structural damage, all standing
water should be removed as quickly as possible.
Dry Out Your Home
Excess moisture in the home is an indoor air
quality concern for three reasons:
	Microorganisms brought into the home during
flooding may present a health hazard. These
organisms can penetrate deep into soaked,
porous materials find later be released into air or
water. Coming in contact with air or water that
contains these organisms can make you sick.
	High humidity and moist materials provide ideal
environments for the excessive growth of
microorganisms that are always present in the
home. This may result in additional health
concerns such as allergic reactions.
	Long term increases in humidify in the home can
also foster the growth of dust mites. Dust mites
are a major cause of allergic reactions and
See Step 4 of the American Red Cross/FEMA
booklet, Repairing Your Flooded Home, on steps
that should be taken to open up and dry out ceilings,
walls, and floors in the home.
Be patient The drying out process could take
several weeks, and growth of microorganisms will
continue as long as humidity is high. If the house is

not dried out properly, a musty odor, signifying
growth of microorganisms, can remain long after .
the flood.
Remove Wet Materials
It can be difficult to throw away items in a home,
particularly those with sentimental value. However,
keeping certain items that were soaked by water may
be unhealthy. Some materials tend to absorb and
keep water more than ofriers. As a general rule:
Materials that are wet and cannot be thoroughly
cleaned and dried should be discarded, as they can
remain a source of microbial growth.
 Information on the types of water-damaged
materials, that should be discarded are provided in
Step 4 of the American Red Cross/FEMA booklet,
Repairing Your Flooded Home.
The booklet suggests that you may be able to dry
out and save certain building materials (for example,
wallboard, fiberglass insulation, and wall-to-wall
carpeting that were soaked only with clean
rainwater; and plaster). You may, however, want to
consider removing and replacing them to avoid
indoor air quality problems. Because they take a
lpng time to dry, they may be a source of microbial
In addition, fiberboard, fibrous insulation, and
disposable filters should be replaced, if they are
present in your heating and air conditioning system
and contacted water. (If a filter was designed to be
cleaned with water and was in contact with clean
rainwater only, ensure that it is thoroughly cleaned
before reinstalling.)
Avoid Problems from the Use of Cleaners
and Disinfectants
The cleanup process involves thorough washing
and disinfecting of the walls, floors, closets, shelves,
and contents of the house. In most cases, common
household cleaning products and disinfectants are
used for this task. FEMA also suggests the use of
disinfectants and sanitizers on the duct work for the
heating and air conditioning system, if it has been
Disinfectants and sanitizers contain toxic
substances. The ability of chemicals in other
household products used for cleaning to cause health
effects varies greatly, from those with no known
health effect to those that are highly toxic. Read and
follow label instructions carefully, and provide fresh
air by opening windows and doors. If it is safe for
you to use electricity and the home is dry, use fans
both during and after the use of disinfecting,
cleaning, and sanitizing products.
Be careful about mixing household cleaners and
disinfectants together. Check labels for cautions on
this. Mixing certain types of products can produce
toxic fumes and result in injury and even death.
Avoid Carbon Monoxide Poisoning
Carbon monoxide is a colorless, odorless gas that
can be lethal at high levels. Carbon monoxide levels
can build up rapidly if certain types of combustion
devices (for example, gasoline-powered generators,
camp stoves and lanterns, or charcoal-burning
devices) are used indoors. Do not use combustion
devices designed for outdoor use indoors.
Avoid Problems from Airborne Asbestos
and Lead Dust
Elevated concentrations of airborne asbestos can .
occur if asbestos-containing materials present in the
home are disturbed. Airborne asbestos can cause
lung cancer and mesothelioma, a cancer of the chest
and abdominal linings. If you know or suspect that
your home contains asbestos, contact the EPA TSCA
Assistance Information Service at 202 554-1404 for
information on steps you should take to avoid
Lead is a highly toxic metal which produces a
range of adverse health effects, particularly in young
children. Disturbance or removal of materials
containing lead-based paint may result in elevated
concentration of lead dust in the air. If you know or
suspect that your home contains lead-based paint,
contact the EPA lead hotline at 800 LEAD-FYI for
information on steps you should take to avoid
Additional Information
Additional copies of this fact sheet, and other
information on indoor air quality, are available
U.S. Environmental Protection Agency
Phone: 800 438-4318 or 301 585-9020
Copies of the American Red Cross/FEMA booklet
Repairing Your Flooded Home are available from:
FEMA Publications	FEMA Public Affairs
P.O. Box 70274	Phone: 202-646-4600
Washington, DC 20024
American Red Cross
Publication Number ARC 4477
See your telephone book for the local chapter office.