Increasing attention is being paid to the subject of air pollution, with the bulk of previous work being done in animal models suggesting that exposure to air pollution causes atherosclerosis—stiffening and calcification of the arteries—in rabbits and mice. The findings of Sara Adar and colleagues, published in PLOS Medicine, take us a step forward in clarifying the broader implications of air pollution by offering further evidence in humans that ambient particulate matter (PM) contributes to the development of cardiovascular disease (CVD).