Short-Term Respiratory Effects of Photochemical Oxidant Exposure in Exercising Children

Abstract

To assess the short-term respiratory effects of photochemical oxidant pollution in children, 66 volunteers—33 boys and 33 girls aged 8 to 11—were exposed in a movable laboratory to polluted Los Angeles area ambient air and to purified air as a control. Exposures lasted one hour, during which subjects exercised continuously at roughly 50 percent of maximal oxygen consumption. Forced expiratory function and symptoms were evaluated prior to and at the end of exposure. The mean ozone concentration in ambient exposures was 0.113 ppm, reflecting an unusually mild pollution season. As a group, the subjects showed no statistically significant untoward responses to ambient air in comparison to purified air, and no significant differences in response between sexes. Nevertheless, regression analyses of individual data indicated a significant (p < 0.05) trend toward forced expiratory dysfunction with increasing ambient ozone concentrations. When the regression analyses were expanded to include older children and adults studied here previously, these children’s reactivity to ambient oxidants appeared similar to the older groups’. However, definitive comparisons among age groups were not possible because their exposure levels differed.