Air Pollution:  What Is Bad for the Arteries Might Be Bad for the Veins

Air pollution is a complex mixture of compounds in gaseous (ozone, carbon monoxide, and nitrogen dioxide) and particulate phases. In the modern urban world, fossil fuel combustion (as used in automobiles and industry) is the major source of anthropogenic pollution.^1- 2 It has become so omnipresent over the past century as to be commonly perceived as a normal natural entity—“the lazy, hazy days of summer.” While we have learned to live within this haze without a second thought, air pollution is neither natural nor benign. Although several gaseous compounds have been associated with illnesses, the most compelling evidence implicates the particulate matter (PM) pollutants as major perpetrators of human diseases.^1- 2 Particulate matter itself is a heterogeneous amalgam of solids and liquids varying in chemical constituents (organic and elemental carbon, nitrates, sulfates, and metals), sources, and sizes (ranging from a few nanometers to 10 μm in aerodynamic diameter).^1- 2 Once thought to pose a threat principally to the lungs, the overall evidence now indicates that the foremost adverse effects of particulates are actually on the cardiovascular (CV) system.^1- 2 Studies conducted worldwide consistently demonstrate that both short- and long-term exposures to PM, even at present-day levels, are associated with a large variety of CV events: myocardial ischemia and infarction, heart failure, stroke, sudden death and arrhythmia, hospitalization for CV diseases, and increased overall CV mortality.^1- 2 Even though the absolute CV risk posed to one individual at any single time point is small, owing to the ubiquitous and constant nature of exposure, PM ranks as the 13th leading cause of global mortality (approximately 800 000 deaths annually).³