Improving indoor environments: reducing allergen exposures.

Homes cannot be made allergen free, but exposure to the major indoor allergens can be reduced. All reduction recommendations are based on the principle of reducing or isolating the source, and certain recommendations can be made on the basis of published evidence. House dust mite avoidance measures include fitting allergen-proof mattress and pillow encasings, washing bedding regularly, and reducing humidity. Furred pet avoidance requires removal of the pet form the home, followed by thorough and repeated cleaning; room air cleaners, washing the pet, and isolating the pet from a bedroom are ineffective alternatives. Cockroach allergen avoidance begins with effective pest control, followed by thorough and repeated cleaning; 1 to 2 months are required to eliminate roaches, and an additional 4 to 6 months are required to remove residual allergen. Once allergen levels have been reduced, continued efforts are necessary to maintain the home free of allergen sources.