Healthy active children, 7 to 13 years old, in a summer recreational camp were chosen as subjects to investigate the acute effects of exposure to ambient-air pollution. Pulmonary-function tests were administered at the camp on 16 days during a five week period in 1982. Ambient-air-pollution data were collected approximately 6 km from the camp. For each of the 39 children tested on six or more days, a linear regression was calculated between the peak one-hour ozone concentration for a given day and each of three functional parameters determined for the same day from the spirograms: forced vital capacity (FVC), Forced expiratory volume in 1 second (PEV1), and peak expiratory flow rate (PEFR). All mean slopes were negative, except for FVC in boys, indicating a general tendency for decreased function with increasing ozone concentration; however only PEFR mean slopes for girls and for all subjects were statistically significantly different from zero. For each of 49 children seen on four or more days, a summary weighted correlation coefficient between peak ozone level and each of the three pulmonary function parameters was calculated. As in the regression analysis, decrements in PEFR were significantly correlated with the ozone exposure. Overall, the decrements were small,more » approximately a 10% decrease in PEFR with an ozone exposure level of 120 ppb.« less