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Mold: Controlling Mold

Mold: Controlling Mold

Fixing pipes

Hidden Mold

Mold can grow in areas of your home that are hard to see. Such areas include the backside of drywall, wallpaper, or paneling. Molds can grow on the top side of ceiling tiles, or underneath carpets in the padding. It might be found inside walls around leaking pipes or in the duct work in your home.

Common Moisture Sources

Indoors: cooking, condensation, dishwashing, house plants, humidifiers, un-vented clothes dryers, indoor clothes lines, bathing, improper venting of combustion appliances and plumbing leaks.

Outdoors: flooding, seasonal high humidity, ground moisture, wet building materials and rain or snowmelt.

Reducing Moisture Sources

Controlling moisture is the key to preventing indoor mold growth. You will want to act quickly to clean up and dry any water-damaged areas. Mold can begin to grow in 24-48 hours. Here is what you can do:

Will air cleaners eliminate mold from my home?

Some air cleaners will remove larger mold spores from the air, but they cannot remove many of the smaller mold spores and they do nothing to remove mold spores that have settled out of the air and fallen onto surfaces such as walls, floors, furniture, etc. Air cleaners that produce ozone are not effective at eliminating mold. Ozone is a lung irritant and should not be used in an occupied space.

Mold and Air Duct Systems

The air duct system in your home can become contaminated with mold and depending on the construction of the system, it may be able to be cleaned and disinfected. If you have insulated air ducts and insulation gets wet or moldy it cannot be effectively cleaned and should be removed and replaced. If conditions causing mold growth in the first place are not corrected, mold growth will reoccur.

The EPA does not recommend that air ducts be cleaned except on an as-needed basis because of the continuing uncertainty about the benefits of duct cleaning under most circumstances. If a service provider or advertiser asserts that EPA recommends routine duct cleaning or makes claims about its health benefits, you should notify EPA by writing to the address listed at the end of this guidance. EPA does, however recommend that if you have a fuel burning furnace, stove, or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning.

Some research also suggests that cleaning dirty cooling coils, fans, and heat exchanges can improve the efficiency of heating and cooling systems. However, little evidence exists to indicate that simply cleaning the duct system will increase your system's efficiency.

If you think duct cleaning might be a good idea for your home, but you are not sure, talk to a professional. The company that services your heating and cooling system may be a good source of advice. You may also want to contact professional duct cleaning service providers and ask them about the services they provide. Remember, they are trying to sell you a service, so ask questions and insist on complete knowledgeable answers.


Controlling Mold Growth in the Home (PDF: 73 KB)
How does mold grow? Includes conditions that support mold growth and how to prevent it. (Source: Kansas University, September 1995).

Purdue Fact Sheet: Preventing Mold Growth (PDF: 35 KB)

Purdue Fact Sheet: Mold Outside Your Home (PDF: 32 KB)

EPA: Guide to Air Cleaners in the Home
The agency does not recommend air cleaning devices or manufacturers.

EPA: Use and Care of Home Humidifiers
Proper care and cleaning, types, and associated pollutant of humidifiers.

EPA: Mold Remediation in Schools and Commercial Buildings
Guidance on prevention, water damage, protective equipment, and mold sampling.