Associations between Long-term Ozone Exposure and Lung Function in Chinese Young Adults: A Longitudinal Cohort Study

Background: Increasing evidence is appearing that ozone has adverse effects on health. However, the association between long-term ozone exposure and lung function is still inconclusive, especially in developing regions with high ozone levels. Objectives To investigate the associations between long-term exposure to ozone and lung function in Chinese young adults. Methods We conducted a prospective cohort study among 1594 college students with a mean age of 19.2 years at baseline in Shandong, China from September 2020 to September 2021. Lung function indicators including forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced expiratory flow at the 25th, 50th, and 75th percentile of the FVC (FEF25, FEF50, and FEF75) and mean flow rate between 25% and 75% of the FVC (FEF25-75) were measured. Daily 10km×10km ozone concentrations come from a well-validated data-fusion approach and the time-weighted average concentrations during 12 months before the lung function test was defined as the long-term ozone exposure. The associations between long-term ozone exposure and lung function indicators in Chinese young adults were investigated using a linear mixed effects model, followed by stratified analyses regarding sex and BMI (Body mass index). Results Each interquartile range (IQR) (8.9 µg/m 3 ) increase in long-term ozone exposure were associated with a -204.3 (95% confidence interval (CI): -361.6, -47.0) ml/s, -146.3 (95% CI: -264.1, -28.4) ml/s, and − 132.8 (95% CI: -239.2, -26.4) ml/s change in FEF25, FEF50, and FEF25-75, respectively. Stronger adverse associations were found in female participants or those with a BMI ≥ 24 kg/m 2 . Conclusion Long-term exposure to ambient ozone is associated with impaired small airway indicators in Chinese young adults. Females and participants with BMI ≥ 24 kg/m 2 have stronger associations.