Causal Association of Prenatal Ozone Exposure with Impaired Lung Function in Childhood.

Human lung growth involves complex processes. Previous studies have suggested associations of prenatal ambient ozone (O3) exposure with impaired lung function, but the causal relationships remain unclear. In this cross-sectional cohort study, pulmonary function tests were conducted on recruited participants. Prenatal exposure to the maximum daily 8 h average of daily O3 (MDA8 O3) and other environmental factors were estimated. Generalized linear model, generalized propensity score, and inverse probability weighting were used to investigate the causal relationship between MDA8 O3 and impaired lung function. Finally, a total of 1058 children were included. Each 10 μg/m3 increase in MDA8 O3 during the entire pregnancy, the first trimester, and the third trimester was positively associated with the risk of impaired lung function in childhood, with odd ratios and 95% confidence intervals of 1.52 (95%CI: 1.06-2.18), 1.22 (95%CI: 1.06-1.41), and 1.47 (95%CI: 1.19-1.83), respectively. The associations for participants exposed to a high ambient temperature (TM), low relative humidity (RH), and low residential greenness during the pregnancy were higher. Prenatal exposure to higher MDA8 O3 concentrations may cause impaired lung function in childhood. The adverse influence of the presence of O3 may be amplified by elevated ambient TM and attenuated by RH and residential greenness.