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Healthy Indoor Air for America's Homes
Biological Pollutants (like molds and dust mites)

Q: What are some of the biological problems I should be concerned about?
A: Molds, mildew, fungi, bacteria and dust mites are some of the main biological pollutants inside the house. Some, such as pollen, are generated outside the home. Mold and mildew are generated in the home and release spores into the air. Mold, mildew, fungi and bacteria are often found in areas of the home that have high humidity levels, such as bathrooms, kitchens, laundry rooms or basements. Dust mites and animal dander are problematic when they become airborne during vacuuming, making beds or when textiles are disturbed. 

Q: What are some of the health effects?
A: Allergic reactions are the most common health problems associated with biological pollutants. Symptoms often include watery eyes, runny nose and sneezing, nasal congestion, itching, coughing, wheezing and difficulty breathing, headache, dizziness and fatigue. Dust mites have been identified as the single most important trigger for asthma attacks. 

Q: How are biological contaminants transported through the house?
A: Molds and dust mites thrive in areas of high humidity. Mold grows on organic materials such as paper, textiles, grease, dirt and soap scum. Mold spores float throughout the house, forming new colonies where they land. Dust mites thrive on dead human skin cells and in textiles such as bedding, carpeting and upholstery. When these textiles are disturbed during vacuuming, making beds or walking on carpet, the dust particles become airborne. Pollen, plant material that enters through windows or on pets, and animal dander also become airborne when disturbed. Infectious diseases caused by bacteria and viruses are generally passed from person to person through physical contact, but some circulate through indoor ventilation systems. 

Q: If I'm concerned about the biological contaminants in my home, what can I do to deal with the problem?
A: There are no practical tests for biological contaminants for use by non-professionals. However there are signs to watch for. You can sometimes see and smell mold colonies growing on surfaces. Mold growth should be suspected wherever there are water stains, standing water or moist surfaces. 

Q: How do I clean up mold?
a: According to the U.S. environmental Protection Agency (EPA), if the moldy area is less than about 10 square feet (less than roughly a 3 ft. by 3 ft. patch), in most cases, you can handle the job yourself, following the guidelines below. However:

If there has been significant water damage, and/or mold growth covers more than 10 square feet, consult the U.S. Environmental Protection Agency (EPA) guide: Mold Remediation in Schools and Commercial Buildings. It is available free by calling the EPA Indoor Air Quality Information Clearinghouse at (800) 438-4318, or on the internet at:

If you choose to hire a contractor to do the cleanup, make sure the contractor has experience cleaning up mold. Check references and ask the contractor to follow the recommendations in EPA's Mold Remediation in Schools and Commercial Buildings, the guidelines of the American Conference of Governmental Industrial Hygienists (ACGIH), or other guidelines form professional or government organizations.

If you have health concerns, consult a health professional before starting cleanup.

For do-it-yourself clean-up, note that the use of a disinfecting chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold remediation, although there may be instances where 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; background levels of mold spores will remain - these spores will grow if the moisture problem has not been resolved. If you choose to use disinfectants or biocides, always ventilate the area. Out door air may need to be brought in with fans. Never mix chlorine bleach solution with other cleaning solutions or detergents that contain ammonia because toxic fumes could be produced.

In instances when a biocide is NOT used, simply damp-wipe surfaces with plain water or with water and detergent solution (except wood - use wood floor cleaner); scrub as needed. Always dry completely after cleanup is completed.

In order to limit your exposure to airborne mold during cleanup, you should wear an N-95 respirator, available at many hardware stores. In order to be effective, the respirator or mask must fit properly, so carefully follow the instructions supplied with the respirator.

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