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Because of their opportunistic nature, molds (also known as fungi) are often a source of environmental inhalants in the home. Fungi are generally dependent on other organic substances for nutrients and energy. These molds generally grow in refrigerators, shower stalls, basements, houseplant mulch, and filters used with evaporative coolers and humidifiers.

Although most fungi grow best in warm humid environments, there is no region of the earth’s surface where they do not exist. They are found from the arctic to the tropic zones, in both salt and fresh water, and in desert soils. Depending on the type of mold, spores may be dispersed by rainfall, humidity or wind. Spores are most commonly found in homes near lowland areas and lakes, and older homes with damp basements.

The attic is another prominent place for mold growth.

Molds can cause year-round clinical signs with flare-ups during the winter months or during humid seasons. The following are some of the most common molds:


Windows, doorways, basements, evaporative coolers and humidifiers


House plants and houseplant mulch, kitchen mold


Outdoor fungus of grasses and cereal grains


Vegetable crops, decaying plant material, damp paper, canvas, cotton fabric.


Bathrooms, shower stalls, condensation on tiles, behind baseboards, wood paneling and floors.


Soil, fruits, breads, and cheeses


Stored fruits and vegetables, field crops

There are several steps you can take to control the growth of molds in your home.

-Spray wherever possible with fungicidal products to help eliminate spores.

-Change filters on cooling systems, furnaces, and humidifiers frequently. Use dehumidifiers to reduce the population of mold spores.

-Avoid houseplants, as the mulch tends to encourage mold growth. If you cannot remove houseplants, try spreading fish tank charcoal over the soil.

-Be sure to add algae killer to your fish tank. Scrub the decorations with chlorine bleach and rinse well before returning them to the tank.

-Use synthetic fibers in pet bedding. Wash pet bedding frequently in hot water.

-If the pet sleeps in the bed, frequently wash bedding in hot water.

For more information on mold related issues including mold cleanup and moisture control/condensation/humidity issues, you can call the EPA Indoor Air Quality Information Clearinghouse at (800) 438-4318 or visit /iaq/molds.