The indoor environment contains unique pollutants, such as environmental tobacco smoke and indoor allergens. In addition, air pollutants may reach higher levels indoors than outdoors, and in some instances may exceed the national standards for outdoor exposure. Nonindustrial indoor settings, such as offices, residences, and vehicles, also have air quality problems. Although the role of occupational air pollutants (organic and inorganic) in causing complaints in the workplace has been clearly documented, the relationship between poor air quality and health complaints is often controversial. The main causes of poor indoor air quality are an inadequate ventilation or fresh air intake, biologic contamination of the indoor environment, and an accumulation of noxious compounds. A list of important indoor air pollutants is shown in Table I. Because indoor allergen concentrations are higher in homes than in public places, a greater effort should be made to control allergens at home. A reason for this difference may be the more aggressive chemical treatment of carpets in public places. However, in some instances high mite, cat, and dog allergen levels have been detected in schools and day care centers. These findings have important implications for families who are practicing allergen avoidance at home because the effort and time spent controlling allergen exposure could be jeopardized by exposure in the school environment.' Studies conducted in schools have demonstrated that carpets contain high levels of a variety of allergens including pollen, cat, dog, food, mite, and mold allergens.2 Carpets in schools and homes are an important reservoir of allergens.