Effects of ambient ozone on lung function in children over a two-summer period.

Abstract

There is a general consensus that short term exposure to ozone (O3) causes a decrease in lung function parameters such as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). The objective of this study was to assess the reproducibility of lung function decrements after ambient O3 exposure over a two-summer period. The authors studied 797 children with a mean age of 8.2 yrs (95% confidence interval: 6.9-9.5) from the second and third grades of ten elementary schools in Austria and southwestern Germany. At the outset the various study locations were stratified into three groups with low (L), medium (M) and high (H) O3 exposure (range of mean O3 concentration in the locations April-October 1994: 24-30 (L); 33-38 (M); 44-52 (H) parts per billion (ppb)). Four lung function tests were performed on each child between March 1994 and November 1995. The increases in FVC and FEV1 recorded from one test period to the next were expressed as mL x day(-1). A significantly lower FVC and FEV1 increase was observed in children exposed to high ambient O3 concentration during the summer season. (FVC in summer 1994: 0.83 (L); 0.56 (M); 0.55 (H) mL x day(-1); p=0.004; and summer 1995: 0.80 (L); 0.63 (M); 0.56 (H) mL x day(-1); p=0.011; FEV1 in summer 1994: 0.48 (L); 0.34 (M); 0.18 (H) mL x day(-1); p=0.004 and summer 1995: 0.68 (L); 0.45 (M); 0.41 (H) mL x day(-1), p=0.006). There was no significant difference in FVC or FEV1 increase between the groups during the winter period. Adjusting for sex, age, height and passive smoke exposure, linear regression revealed a statistically significant negative association of average ambient O3 concentration with the FVC and FEV1 increase in both summers. During the winter period no association of O3 with FVC or FEV1 was observed. In conclusion, in two consecutive summer periods the authors found reproducible lung function decrements in children exposed to high levels of ambient ozone. Reoccurrence of ozone associated lung function deficits might increase the likelihood of persisting effects on the childrens' airways.