Long-term Ambient Fine Particulate Matter Air Pollution and Lung Cancer in a Large Cohort of Never-Smokers

Rationale: There is compelling evidence that acute and chronic exposure to ambient fine particulate matter (PM2.5) air pollution increases cardiopulmonary mortality. However, the role of PM2.5 in the etiology of lung cancer is less clear, particularly at concentrations that prevail in developed countries and in never-smokers. Objectives: This study examined the association between mean long-term ambient PM2.5 concentrations and lung cancer mortality among 188,699 lifelong never-smokers drawn from the nearly 1.2 million Cancer Prevention Study-II participants enrolled by the American Cancer Society in 1982 and followed prospectively through 2008. Methods: Mean metropolitan statistical area PM2.5 concentrations were determined for each participant based on central monitoring data. Cox proportional hazards regression models were used to estimate multivariate adjusted hazard ratios and 95% confidence intervals for lung cancer mortality in relation to PM2.5. Measurements and Main Results: A total of 1,100 lung cancer deaths were observed during the 26-year follow-up period. Each 10 mu g/m(3) increase in PM2.5 concentrations was associated with a 15-27% increase in lung cancer mortality. The association between PM2.5 and lung cancer mortality was similar in men and women and across categories of attained age and educational attainment, but was stronger in those with a normal body mass index and a history of chronic lung disease at enrollment (P < 0.05). Conclusions: The present findings strengthen the evidence that ambient concentrations of PM2.5 measured in recent decades are associated with small but measurable increases in lung cancer mortality.