Tiny particles of air pollution—called fine particulate matter—can have a range of effects on health, and exposure to high levels is a known risk factor for cardiovascular disease. New research led by investigators at Massachusetts General Hospital (MGH) reveals that fine particulate matter has a detrimental impact on cardiovascular health by activating the production of inflammatory cells in the bone marrow, ultimately leading to inflammation of the arteries. The findings are published in the European Heart Journal.