Are ultrafine particles a risk factor for cardiovascular diseases?

1885-5857/$ – see front matter 2011 Sociedad Esp doi:10.1016/j.rec.2011.05.006 Numerous epidemiological studies support the association of exposure to air pollution with adverse health effects leading to enhanced morbidity and mortality of considerable significance. In fact, the World Health Organization ranks it as the 13th leading cause of worldwide mortality. Cumulative evidence over the last decade suggests that the largest portion of air pollution-related mortality is due to cardiovascular diseases, on the basis of which it has been proposed to be a ‘‘modifiable’’ novel cardiovascular risk factor of great importance. While air pollution is a complex mixture of compounds in the gaseous and particle phases, more evidence implicates the particulate matter (PM) components as responsible for a major portion of the cardiovascular effects. The PM components are classified according to their aerodynamic diameter into size fractions such as PM10 (‘‘thoracic’’ particles, < 10 mm), PM2.5-10 (‘‘coarse’’ particles, 2.5 to 10 mm), PM2.5 (‘‘fine’’ particles, < 2.5mm) and UFP (‘‘ultrafine’’ particles, < 0.1 mm). These PM of different sizes appear to carry different abilities to cause harmful effects and there is increasing debate about the notion that systemic cardiovascular effects could be favored by a smaller particle size. Thus, exposure to ambient PM leads to enhanced cardiovascularmorbidity andmortality due to amyriad of acute and chronic effects. Acute exposure to PM has been associated with the triggering of acute myocardial infarctions, discharge of implanted automatic cardioverter defibrillators, hospitalizations for ischemic strokes, and decompensated congestive heart failure. Therefore, the article by Domı́nguez-Rodrı́guez et al. published in Revista Española de Cardiologı́a is very important as it approached the question whether air pollution could preferentially associate with hospital admissions due to heart failure (HF) vs acute coronary syndromes (ACS), in a terciary university hospital in Tenerife, Spain. While exposure to ambient particulate could enhance the incidence of both HF and ACS, leading to increased hospital admissions due to both causes, the study design evaluated whether there were differences between the two types of admissions. There was a small variation in environmental exposure parameters which impeded the authors from conducting a time series analysis.