POSSIBLE MECHANISMS FOR THE RESPIRATORY-TRACT EFFECTS OF NONCARCINOGENIC INDOOR-CLIMATE POLLUTANTS AND BASES FOR THEIR RISK ASSESSMENT

This review outlines the effects of pollutants on the lungs. Mechanism s and effects relevant to the assessment of indoor-air risk are especi ally dealt with. Important mediators have also been considered. Concen tration-effect relationships exist for toxic reactions, sensitization reactions, and neurogenic effects. If Harber's Law is used for extrapo lations from higher concentrations to the lower indoor-air levels, the indoor-air risk estimate may exceed the real risk. Additivity seems t o apply to toxic and neurogenic effects of low doses. Only already sen sitized subjects and possible subjects with a profound alpha(1)-antitr ypsin deficiency appear to be extremely sensitive, and a safety factor of 10 seems adequate for the protection of other groups. Thus combini ng occupational exposure limits (GEL), Harber's Law, and the safety fa ctor suggests that no direct lung effects should be expected from a su bstance if the exposure level does not exceed 1/40 . GEL.