ACUTE RESPIRATORY EFFECTS OF SUMMER SMOG IN PRIMARY-SCHOOL CHILDREN

In 535 primary school children we studied the effects of exposure to s ummer smog on respiratory health. Baseline measurements were performed during low air pollution levels (max. 24-h concentrations of SO2, O-3 and NO, were 55, 49 and 58 mu g/m(3), respectively) consisting of lun g function measurements using spirometry and the forced oscillation te chnique (FOT) and the prevalence of respiratory symptoms, determined b y a written questionnaire. During a summer smog episode, 212 randomly chosen children were re-examined, characterised by 8-h ozone levels > 120 mu g/m(3) (max. 163 mu g/m(3)) and I-h ozone levels > 160 mu g/m(3 ) (max. 215 mu g/m(3)). Overall, small decrements were observed in the forced expiratory volume in 1 s (FEV(1)), (P < 0.05) and the forced e xpiratory volume between 25 and 75% of the vital capacity (FEF(25-75%) ) (P < 0.01). On the contrary, there was a statistically significant d ecrease in resistance parameters. No increases were observed in the pr evalence of acute respiratory symptoms. In conclusion, in this study w e found small inconsistent changes in lung function and no increase of respiratory symptoms after short-time exposure to moderately high ozo ne levels.