Researchers in Italy recently studied the effect of air pollution on the risk of developing blood clots (DVT). Deep vein thrombosis can lead to pulmonary embolism, a potentially fatal disease process, occurring when a blood clot breaks off and travels to the lung. An embolism can block air flow, either partially or completely. While other risk factors for developing blood clots are well known - immobility, recent trauma and surgery, cancer, and oral contraceptives are all risk factors for deep vein thrombosis - according to one study, poor air quality seems to increase the risk of developing blood clots as well. For an article on the risk of DVT being increased by air pollution, click the link below.