Mold Basics
Why is mold growing in my home?
Molds are part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic
matter such as fallen leaves and dead trees, but indoors, mold growth should be avoided. Molds reproduce by means
of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin
growing indoors when mold spores land on surfaces that are wet. There are many types of mold, and none of them will
grow without water or moisture.
Can mold cause health problems?
Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing. Molds
have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions),
irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may
cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as
sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be
immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In
addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic
people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold.
Research on mold and health effects is ongoing. For more detailed information consult a health professional. You
may also wish to consult your state or local health department.
How do I get rid of mold?
It is impossible to get rid of all mold and mold spores indoors, some mold spores will be found floating through the air
and in house dust. The mold spores will not grow if moisture is not present. Indoor mold growth can and should be
prevented or controlled by controlling moisture indoors. If there is mold growth in your home, you must clean up the
mold and fix the water problem. If you clean up the mold, but don't fix the water problem, then, most likely, the mold
problem will come back.
Who Should Do the Cleanup?
Who should do the cleanup depends on a number of factors. You should consider the location of the mold (for
example, a shower stall or a wall surface), the amount of surface area affected, and the type of building materials
affected. If there has been extensive water damage or if removal of any building materials is expected to be required,
consultation with a qualified remediation professional is usually best to ensure that mold spores are not inadvertently
spread through other parts of the home.
If you choose to hire a contractor (or other professional service provider) to do the cleanup, make sure the contractor
is certified by the Indoor Air Quality Association (IAQA, www.iaqa.org) and/or the Institute of Inspection,
Cleaning & Restoration (IICRC, www.iicrc.org).
If you suspect that the heating/ventilation/air conditioning (HVAC) system may be contaminated with mold (it is part of
an identified moisture problem, for instance, or there is mold near the intake to the system), consult a qualified mold
remediation or duct cleaning contractor. Do not run the HVAC system if you know or suspect that it is contaminated with
mold - it could spread mold throughout the building.
If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who
has experience cleaning and fixing buildings damaged by contaminated water.
If you have health concerns, consult a health professional before starting cleanup.
How Do I Know When the Remediation or Cleanup is Finished?
You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered
finished.
Moisture and Mold Prevention and Control Tips
Actions that will help to reduce humidity:
Actions that will help prevent condensation:
Testing or Sampling for Mold
Is sampling for mold needed?
Air samples are often used as a method of determining if hidden sources of mold exist. Air samples are also needed by
Industrial Hygenists and other professionals when assessing and determining the scope of a mold remediation project.
Air samples also provide a baseline for comparison when work is completed; clearance testing should always be
performed after any professional remediation work is complete to ensure that a normal fungal ecology exists in the
remediated area.
supply information necessary to determine the extent of a remeare also Surface sampling may be useful to determine
if an area has been adequately cleaned or remediated. Sampling for mold should be conducted by professionals who
have specific experience in designing mold sampling protocols, sampling methods, and interpreting results. Sample
analysis should follow analytical methods recommended by the American Industrial Hygiene Association (AIHA), the
American Conference of Governmental Industrial Hygienists (ACGIH), or other professional organizations.
Suspicion of hidden mold
You may suspect hidden mold if a building smells moldy, but you cannot see the source, or if you know there has been
water damage and residents are reporting health problems. Mold may be hidden in places such as the back side of dry
wall, wallpaper, or paneling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible
locations of hidden mold include areas inside walls around pipes (with leaking or condensing pipes), the surface of
walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof
leaks or insufficient insulation).
Investigating hidden mold problems
Investigating hidden mold problems may be difficult and will require caution when the investigation involves disturbing
potential sites of mold growth. For example, removal of wallpaper can lead to a massive release of spores if there is
mold growing on the underside of the paper. If you believe that you may have a hidden mold problem, consider hiring
an experienced professional.
Cleanup and Biocides
Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such
as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup. There may be
instances, however, when professional judgment may indicate its use (for example, when immune-compromised
individuals are present). In most cases, it is not possible or desirable to sterilize an area; a background level of mold
spores will remain - these spores will not grow if the moisture problem has been resolved. If you choose to use
disinfectants or biocides, always ventilate the area and exhaust the air to the outdoors. Never mix chlorine bleach
solution with other cleaning solutions or detergents that contain ammonia because toxic fumes could be produced.
Please note: Dead mold may still cause allergic reactions in some people, so it is not enough to simply kill the mold, it
must also be removed.
Ten Things You Should Know About Mold
1. Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other
respiratory complaints.
2. There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor
mold growth is to control moisture.
3. If mold is a problem in your home or school, you must clean up the mold and eliminate sources of moisture.
4. Fix the source of the water problem or leak to prevent mold growth.
5. Reduce indoor humidity (to 30-60%) to decrease mold growth by:
7. Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles,
that are moldy, may need to be replaced.
8. Prevent condensation: Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls,
roof, or floors) by adding insulation.
9. In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by
classroom sinks, or on concrete floors with leaks or frequent condensation).
10. Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present.
There are molds that can grow on wood, paper, carpet, and foods.
- The key to mold control is moisture control.
- If mold is a problem in your home, you should clean up the mold promptly and fix the water problem.
- It is important to dry water-damaged areas and items within 24-48 hours to prevent mold growth.
Why is mold growing in my home?
Molds are part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic
matter such as fallen leaves and dead trees, but indoors, mold growth should be avoided. Molds reproduce by means
of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin
growing indoors when mold spores land on surfaces that are wet. There are many types of mold, and none of them will
grow without water or moisture.
Can mold cause health problems?
Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing. Molds
have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions),
irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may
cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as
sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be
immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In
addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic
people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold.
Research on mold and health effects is ongoing. For more detailed information consult a health professional. You
may also wish to consult your state or local health department.
How do I get rid of mold?
It is impossible to get rid of all mold and mold spores indoors, some mold spores will be found floating through the air
and in house dust. The mold spores will not grow if moisture is not present. Indoor mold growth can and should be
prevented or controlled by controlling moisture indoors. If there is mold growth in your home, you must clean up the
mold and fix the water problem. If you clean up the mold, but don't fix the water problem, then, most likely, the mold
problem will come back.
Who Should Do the Cleanup?
Who should do the cleanup depends on a number of factors. You should consider the location of the mold (for
example, a shower stall or a wall surface), the amount of surface area affected, and the type of building materials
affected. If there has been extensive water damage or if removal of any building materials is expected to be required,
consultation with a qualified remediation professional is usually best to ensure that mold spores are not inadvertently
spread through other parts of the home.
If you choose to hire a contractor (or other professional service provider) to do the cleanup, make sure the contractor
is certified by the Indoor Air Quality Association (IAQA, www.iaqa.org) and/or the Institute of Inspection,
Cleaning & Restoration (IICRC, www.iicrc.org).
If you suspect that the heating/ventilation/air conditioning (HVAC) system may be contaminated with mold (it is part of
an identified moisture problem, for instance, or there is mold near the intake to the system), consult a qualified mold
remediation or duct cleaning contractor. Do not run the HVAC system if you know or suspect that it is contaminated with
mold - it could spread mold throughout the building.
If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who
has experience cleaning and fixing buildings damaged by contaminated water.
If you have health concerns, consult a health professional before starting cleanup.
How Do I Know When the Remediation or Cleanup is Finished?
You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered
finished.
- You should have completed mold removal. Visible mold and moldy odors should not be present. Please note
that mold may cause staining and cosmetic damage. - You should have revisited the site(s) shortly after cleanup and it should show no signs of water damage or mold
growth. - People should have been able to occupy or re-occupy the area without health complaints or physical
symptoms. - Ultimately, this is a judgment call; there is no easy answer. If you have concerns or questions call the EPA Indoor
Air Quality Information Clearinghouse IAQ INFO at (800) 438-4318.
Moisture and Mold Prevention and Control Tips
- Moisture control is the key to mold control, so when water leaks or spills occur indoors - ACT QUICKLY. If wet or
damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow. - Clean and repair roof gutters regularly.
- Make sure the ground slopes away from the building foundation, so that water does not enter or collect around
the foundation. - Keep air conditioning drip pans clean and the drain lines unobstructed and flowing properly.
- Keep indoor humidity low. If possible, keep indoor humidity below 60 percent (ideally between 30 and 50
percent) relative humidity. Relative humidity can be measured with a moisture or humidity meter, a small,
inexpensive ($10-$50) instrument available at many hardware stores. - If you see condensation or moisture collecting on windows, walls or pipes ACT QUICKLY to dry the wet surface
and reduce the moisture/water source. Condensation can be a sign of high humidity.
Actions that will help to reduce humidity:
- Vent appliances that produce moisture, such as clothes dryers, stoves, and kerosene heaters to the outside
where possible. (Combustion appliances such as stoves and kerosene heaters produce water vapor and will
increase the humidity unless vented to the outside.) - Use air conditioners and/or de-humidifiers when needed.
- Run the bathroom fan or open the window when showering. Use exhaust fans or open windows whenever
cooking, running the dishwasher or dishwashing, etc.
Actions that will help prevent condensation:
- Reduce the humidity (see above).
- Increase ventilation or air movement by opening doors and/or windows, when practical. Use fans as needed.
- Cover cold surfaces, such as cold water pipes, with insulation.
- Increase air temperature.
Testing or Sampling for Mold
Is sampling for mold needed?
Air samples are often used as a method of determining if hidden sources of mold exist. Air samples are also needed by
Industrial Hygenists and other professionals when assessing and determining the scope of a mold remediation project.
Air samples also provide a baseline for comparison when work is completed; clearance testing should always be
performed after any professional remediation work is complete to ensure that a normal fungal ecology exists in the
remediated area.
supply information necessary to determine the extent of a remeare also Surface sampling may be useful to determine
if an area has been adequately cleaned or remediated. Sampling for mold should be conducted by professionals who
have specific experience in designing mold sampling protocols, sampling methods, and interpreting results. Sample
analysis should follow analytical methods recommended by the American Industrial Hygiene Association (AIHA), the
American Conference of Governmental Industrial Hygienists (ACGIH), or other professional organizations.
Suspicion of hidden mold
You may suspect hidden mold if a building smells moldy, but you cannot see the source, or if you know there has been
water damage and residents are reporting health problems. Mold may be hidden in places such as the back side of dry
wall, wallpaper, or paneling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible
locations of hidden mold include areas inside walls around pipes (with leaking or condensing pipes), the surface of
walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof
leaks or insufficient insulation).
Investigating hidden mold problems
Investigating hidden mold problems may be difficult and will require caution when the investigation involves disturbing
potential sites of mold growth. For example, removal of wallpaper can lead to a massive release of spores if there is
mold growing on the underside of the paper. If you believe that you may have a hidden mold problem, consider hiring
an experienced professional.
Cleanup and Biocides
Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such
as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup. There may be
instances, however, when professional judgment may indicate its use (for example, when immune-compromised
individuals are present). In most cases, it is not possible or desirable to sterilize an area; a background level of mold
spores will remain - these spores will not grow if the moisture problem has been resolved. If you choose to use
disinfectants or biocides, always ventilate the area and exhaust the air to the outdoors. Never mix chlorine bleach
solution with other cleaning solutions or detergents that contain ammonia because toxic fumes could be produced.
Please note: Dead mold may still cause allergic reactions in some people, so it is not enough to simply kill the mold, it
must also be removed.
Ten Things You Should Know About Mold
1. Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other
respiratory complaints.
2. There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor
mold growth is to control moisture.
3. If mold is a problem in your home or school, you must clean up the mold and eliminate sources of moisture.
4. Fix the source of the water problem or leak to prevent mold growth.
5. Reduce indoor humidity (to 30-60%) to decrease mold growth by:
- a. venting bathrooms, dryers, and other moisture-generating sources to the outside;
b. using air conditioners and de-humidifiers;
c. increasing ventilation;
d. and using exhaust fans whenever cooking, dish washing, and cleaning
7. Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles,
that are moldy, may need to be replaced.
8. Prevent condensation: Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls,
roof, or floors) by adding insulation.
9. In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by
classroom sinks, or on concrete floors with leaks or frequent condensation).
10. Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present.
There are molds that can grow on wood, paper, carpet, and foods.
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