Invited commentary: epidemiologic studies of the impact of air pollution on lung cancer

In this issue of the Journal, Villeneuve et al. (Am J Epidemiol. 2014;179(4):443-451) present epidemiologic evidence supporting the literature on the adverse effects of air pollution on risk of lung cancer. They found that ambient exposure to volatile organic compounds, especially when measured at longer time scales, was associated with increased odds of lung cancer in citizens of Toronto, Ontario, Canada, between 1997 and 2002. Specifically, in fully adjusted models, they observed that an interquartile-range increase in benzene concentration was associated with an odds ratio of 1.51 (95% confidence interval: 1.13, 2.01) using exposure at the time of interview. The odds ratio increased to 1.84 (95% confidence interval: 1.26, 2.68) when time-weighted exposure at all previous addresses was considered. They obtained similar results for exposure to nitrogen dioxide. These findings add weight to the substantial (and rapidly growing) body of literature on the relation of air pollution with lung cancer risk, as well as illustrate important aspects of the effects of different exposure assessment choices and potential sources of key interest.