Air pollution: to the heart of the matter

Air pollution consists of both gaseous and particulate-matter pollutants. The former include nitrogen dioxide (NO2), ozone (O3), and sulphur dioxide (SO2). The latter consist of particulate matter of varying aerodynamic diameter, as defined by cutoff points—for example, particles with diameters of <10 µm (PM10) or <2.5 µm (PM2.5). Because of their small size, these particles can be inhaled deeply into the lungs and deposited in the alveoli. Why should cardiologists care about ambient air? It has long been known that air pollution can adversely affect human health. Extreme levels of pollution may cause markedly increased mortality rates; in this regard one often refers to the Meuse valley fog of 19301 or the London smog of 1952. These episodes initiated successful efforts and legislation to reduce air pollution. Nevertheless, even at current ambient pollution levels, the relation between pollution and excess morbidity and mortality still exists. However, the nature of the pollutants and the type of health effects have shifted, with a special emphasis now being placed on the heart rather than the lungs. Maître et al.2 gathered the available epidemiological evidence on the association between coronary disease and air pollution at current ambient concentrations. From both biological and public health perspectives, one should distinguish between acute and long-term effects of air pollution.