Nagel G, et al. - In humans, air pollution is considered carcinogenic, so researchers assessed if long-term exposure to ambient air pollution was correlated with incidence of gastric and upper aerodigestive tract (UADT) cancer in 11 European cohorts. Long-term exposure to particulate matter below 2.5 μm (PM_2.5) was correlated with gastric cancer, but not with UADT cancers, inferring that air pollution could contribute to gastric cancer risk. Compared to women, men showed higher estimated risks of gastric cancer associated with PM_2.5.