The purpose of this study is to characterize what is know among a broad range of experts whose efforts are directed toward achieving cleaner indoor environments. The twin foci of this study are to (1) evaluate the indoor environmnent, and (2) appraise the knowledge-base commonly available to physicians with respect to human exposure indoors to allergens (including selected biologicals and chemicals that elicit allergic reactions). A committee of experts will be appointed to (1) examine and characterize what is known about the adverse effects on human health caused by reactions, including asthma, to indoor allergens; (2) characterize the magnitude of these disease problems nationally; (3) define the populations commonly affected; and (4) identify the specific causative agents. The study will review published epidemiological reports, estimate economic impacts of these diseases, and determine the risk factors. It will examine methods used in patient diagnoses and measurement of indoor allergen exposures and will evaluate methods of abatement and control o sources of allergens. The study will focus particularly on the types of education that could heighten awareness among primary care physicians, allergists, members of the general public, building maintenance professionals, and technicians about indoor allergens an exposure to them.