Indoor mold (fungus) is very common in humid areas and in homes that have damp areas such as basements. Mold may trigger asthma symptoms, such as wheezing or coughing, or another allergic reaction, such as the rash of atopic dermatitis or stuffy nose of allergic rhinitis. Substances that trigger these reactions are called allergens.

Although there is no strong evidence that reducing damp areas in homes or limiting exposure to them helps decrease allergy and asthma symptoms, taking the following steps may be helpful.

• Store fireplace wood outside the home.
• Clean bathtubs, shower stalls, shower curtains, and windowsills at least once a month with a disinfectant or liquid bleach. Use bleach with caution, because it may irritate your nose. If your nose is irritated, your allergy symptoms may get worse.
• Keep the house aired out and dry. This may be difficult in some seasons and some climates.
• Use an exhaust fan in bathrooms and the kitchen to vent excess moisture.
• Use a dehumidifier during humid weather. Try to keep the humidity in the home below 50%. Molds thrive in higher humidity.
• Seal off or avoid damp areas, such as crawl spaces, attics, or basements. Use a dehumidifier to control mold growth in these areas. Try to avoid materials that have been stored in these areas.
• Remove carpeting from any concrete floors, especially in the basement.
• Repair any water-damaged areas from leaking roofs or basements. Also, check the areas under sinks and around other plumbing for leaks. These areas can be prime mold-growing areas.
• Make sure your clothes dryer vents moist air to the outside.
• Inspect closets for items, such as shoes, that may retain moisture.

Because adults spend one-third of their time and children spend half of their time in their bedrooms, it is important that you take steps to prevent allergens in this room.