The association between long-term exposure to ozone and respiratory morbidity in Chinese adults: a nationwide cross-sectional study

Long-term ozone (O 3 ) exposure is known to be associated with respiratory mortality and hospitalization, but its effects on respiratory morbidity, symptom severity, and quality of life remain undefined. This study was conducted using data from the China Pulmonary Health (CPH) study. Respiratory morbidity was measured by the COPD Assessment Test (CAT) scores, the modified Medical Research Council (mMRC) dyspnea scale, and spirometry-defined COPD. Health-related quality of life was also considered. Long-term O 3 exposure was defined as the annual average of daily maximum 8-hour average (MDA8) O 3 concentrations in the year prior to the survey. Logistic and linear regression models were used to explore the association between long-term O 3 exposure and the health outcomes. Each 10 µg/m 3 increase in O 3 was associated with increased odds of CAT ≥ 10 (measured in participants with a post-bronchodilator FEV 1 /FVC ratio less than 0.8; OR = 1.09, 95% CI:1.00, 1.18), mMRC ≥ 1 (OR = 1.13, 95% CI:1.04, 1.22), and COPD (OR = 1.11, 95% CI:1.05, 1.17), as well as a 0.55-point decline in SF-12 PCS (95% CI: -0.71, -0.39). Positive associations were also observed for some single CAT items. Female and younger participants were identified as subgroups particularly vulnerable to O 3 . Long-term O 3 exposure was associated with the presence of respiratory symptoms, increased prevalence of spirometry-defined COPD, and poorer quality of life. These findings underscore the importance of raising awareness of the respiratory effects of O 3 exposure and the need for O 3 control. Not applicable.