Long-term exposure to ozone and incidence of lung cancer in China: data based on a national population cohort (ChinaHEART)

Objective

Ozone (O₃) is recognized as a predominant and increasingly prevalent gaseous pollutant contributing to the Global Burden of Disease. However, its effect on the development of lung cancer has not been adequately acknowledged.

Methods

Based on Health Evaluation And risk Reduction through nationwide Teamwork (ChinaHEART), a nationwide, population-based cohort study, 2,006,878 participants living in 20,159 communities or villages were passively followed for the incidence of lung cancer through a linkage of data with the National Central Cancer Registry. The average O₃ levels over ten years from the year of enrolment in their respective localities were determined based on geographic coordinates. We conducted Cox proportional-hazards regression models to assess the independent hazard ratios (HRs) associated with O₃ exposure and the development of lung cancer.

Results

During the follow-up of 4.93 million person-years, 4555 new cases of lung cancer were identified. After adjusting for participant characteristics and other environmental factors, we observed a significant positive association between ambient O₃ exposure and lung cancer. Compared with participants in the quartile 1 of O₃, HRs and 95 % confidence intervals (CI) for the other three quartiles were 1.09 (95 % CI: 1.00–1.17), 1.17 (95 % CI: 1.06–1.29) and 1.42 (95 % CI: 1.26–1.59), respectively.

Conclusions

Long-term exposure to ambient O₃ is associated with a substantially higher risk of lung cancer. Further studies are needed to explore its pathogenic mechanisms, as well as to evaluate measures for exposure protection or harm mitigation at the individual or population level.