Severity of health effects associated with building-related illness.

Building-related illness ranges from mild rhinitis to potentially life-threatening hypersensitivity pneumonitis and legionellosis. Sick-building syndrome, consisting of headache, mucous membrane irritation, and fatigue, may be present in 30% of all office workers. Hypersensitivity pneumonitis, asthma, and legionellosis are less common, and it is difficult from existing studies to estimate the incidence of these more severe illnesses. There are even fewer data on an illness now being called multiple chemical sensitivity and its relationship to indoor environments. New studies are needed to estimate the frequency of all building-associated illnesses, and case definitions for these disorders must be delineated.