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

Ozone (O 3 ) is the leading and a growing gaseous pollutant in the Global Burden of Disease, however, its effect on development of lung cancer were unacknowledged. Based on ChinaHEART (Health Evaluation And risk Reduction through nationwide Teamwork), a nationwide, population-based cohort study, 2,006,878 participants living in 20,159 communities or villages were passively followed for incident lung cancer, through a linkage of data with the National Central Cancer Registry. The ten-year average ambient O 3 concentration from 2006 to 2015 in each participant’s living community was ascertained. We conducted Cox proportional-hazards regression models to assess the independent hazard ratios (HRs) of O 3 level on the development of lung cancer. During the follow-up of 4.93 million person-years, 4,555 incident lung cancer cases were confirmed. After adjusting for participant characteristics and other environmental factors, we observed a significant positive association between ambient O 3 exposure and lung cancer. Compared with participants in quartile 1 of O 3 , HRs and 95% confidence intervals for the other three quartiles were 1.04 (0.96-1.14), 1.14 (1.05-1.25), and 1.28 (1.15-1.42), respectively. Long-term exposure to ambient O 3 was associated with a substantially higher risk of lung cancer. Further studies to explore its pathogenic mechanisms, as well as to evaluate measures for exposure protection or harm mitigation, at individual or population level, are needed.