CHAMBER EXPOSURES OF CHILDREN TO MIXED OZONE, SULFUR-DIOXIDE, AND SULFURIC-ACID

To help assess acute health effects of summer air pollution in the eas tern United States, we simulated ambient ''acid summer haze'' as close ly as was practical in a laboratory chamber. We exposed young voluntee rs who were thought to be sensitive to this pollutant mixture on the b asis of previous epidemiologic evidence. Specifically, we exposed 41 s ubjects aged 9-12 y to mixed ozone (0.10 ppm), sulfur dioxide (0.10 pp m), and 0.6-mu m sulfuric acid aerosol (100 +/- 40 mu g/m(3), mean +/- standard deviation) for 4 h, during which there was intermittent exer cise. Fifteen subjects were healthy, and 26 had allergy or mild asthma . The entire group responded nonsignificantly p >.05) to pollution exp osure (relative to clean air), as determined by spirometry, symptoms, and overall discomfort level during exercise. Subjects with allergy/as thma showed a positive association (p =.01) between symptoms and acid dose; in healthy subjects, that association was negative (p =.08). In these chamber-exposure studies, we noted less of an effect than was re ported in previous epidemiologic studies of children exposed to ambien t ''acid summer haze.''