Direct and indirect exposure to air pollution.

Hazardous substances that originally are discharged as air pollutants may find their pathway to human exposure through multiple routes, including ingestion and dermal contact, as well as direct inhalation. The mechanisms for modeling and understanding the fate of air pollutants through atmospheric transport, deposition into water and soil, bioaccumulation, and ultimate uptake to receptor organs and systems in the human body are complex. Pollution prevention programs can be better engineered, pollution priorities can be identified, and greater environmental public health gains (attributable to pollution prevention) can be achieved by evaluating the multiple pathways to human exposure and through improved dosage calculations. A single contaminant source often may represent only a fraction of a total body pollutant burden. Further research is needed on source culpability and attributable risk, long-range transport of air pollutants, human dose contributions by various pathways, better techniques for health risk assessment, and an identification of human behavior patterns that affect exposure and dose.