Acute Respiratory Effects of Los Angeles Smog in Continuously Exercising Adults

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Abstract
Volunteers were exposed in a mobile laboratory to polluted ambient air, and to purified air as a control experiment, during photochemical smog seasons in suburban Los Angeles. During the 1-h exposures, subjects performed continuous, moderate exercise (mean ventilation near 40 L/min). In summer 1980, a group of 60 subjects including seven asthmatics showed statistically significant reductions in lung function test performance, as well as increases in symptoms, with ambient air. Ambient exposures were almost exclusively secondary photochemical products; mean exposure concentrations were 0.165 ppm O3 and 227 μg/m3 TSP. Some relationship between increasing O3 level and increasing severity of response was suggested. In summer 1981, a group of 98, including 50 asthmatics, was studied. They showed smaller mean responses than the previous group, and no suggestion of a dose-response relationship with O3. Mean exposure concentrations were 0.156 ppm O3 and 166 μg/m 3 TSP. It is concluded that short-term effects of moderate exercise in Los Angeles area photochemical smog vary considerably among individuals, and that some may develop respiratory irritation.