Associations between long-term ozone exposure and small airways function in Chinese young adults: a longitudinal cohort study

BackgroundIncreasing evidence is appearing that ozone has adverse effects on health. However, the association between long-term ozone exposure and lung function is still inconclusive.ObjectivesTo investigate the associations between long-term exposure to ozone and lung function in Chinese young adults.MethodsWe 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 were measured in September 2020 and September 2021, including forced vital capacity (FVC), forced expiratory volume in 1 s (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 10 kmx10 km ozone concentrations come from a well-validated data-fusion approach. The time-weighted average concentrations in 12 months before the lung function test were 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, BMI and history of respiratory diseases.ResultsEach interquartile range (IQR) (8.9 mu g/m3) 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 BMI >= 24 kg/m2 and history of respiratory diseases.ConclusionLong-term exposure to ambient ozone is associated with impaired small airway indicators in Chinese young adults. Females, participants with BMI >= 24 kg/m2 and a history of respiratory disease have stronger associations.