Effects of Ambient Ozone on Respiratory Function in Active, Normal Children

Abstract

Respiratory functions were measured on a daily basis by spirometry over a period of 4 wk at a summer camp at Fairview Lake in northwestern New Jersey. Fifty-three boys and 38 girls 8 to 15 yr of age participated in the study on at least 7 days; 37 children were in residence for 4 wk, 34 for the first 2 wk only; and 20 for the last 20 wk. There were 72 whites, 15 blacks, 3 Asians, and 1 Hispanic in the study group. Multiple regression analyses indicated that the O3 concentration in the previous hour, the cumulative daily O3 exposure during the hours between 9 A.M. and the function measurement, ambient temperature, and humidity were the most explanatory environmental variables for daily variations in function, with the 1- h O3 concentration having the strongest influence. Linear regression were performed for each child between O3 concentration and function, and all average slopes were significantly negative (p < 0.05) for FVC, FEV1, PEFR, and FEF25-75 for all children, and for boys and girls separately. Comparable results were obtained in data subsets (i.e., children studied during the first or second 2 wk only, and for data sets truncated at O3 < 80 and O3 < 60 ppb). The average regression slopes (.+-. SE) for FVC and FEV1, respectively, were -1.03 .+-. 0.24 and -1.42 .+-. 0.17 ml/ppb, whereas for PEFR and FEF25-75 they were -6.78 .+-. 0.73 and -2.48 .+-. 0.26 ml/s/ppb. These predict average decrements of 4.9, 7.7, 17, and 11%, respectively, for O3 at the current ambient standard of 120 ppb. The implications of these short-term effects are unknown. However, the results in these free-living children are comparable to those found in chamber studies with comparable exposures.