Health effects of air pollution. A review of clinical studies.

The database for the acute health effects of common outdoor air pollutants is rapidly increasing but important gaps still exist. Greater technical efforts and innovative studies are required to adequately characterize health effects and understand the underlying mechanisms of toxicity. Controlled human exposures provide relevant data about short-term effects and complement animal and epidemiologic investigations. Except for possibly nitrogen dioxide, the clinical data for ozone, sulfur dioxide, and particulates (H2SO4) at contemporary levels indicate potentially untoward or adverse physiologic or clinical responses in healthy individuals and sensitive groups such as children, adolescents, and asthmatic patients. Exercise, duration, and other exposure factors may potentiate pollutant effects on symptoms, lung function, nonspecific bronchial reactivity, mucociliary clearance, and BAL markers of inflammation. Continued animal, clinical, and epidemiologic research of both short- and long-term health effects is clearly needed to support or limit future regulatory decisions regarding the quality of outdoor air.