Context There is considerable literature indicating a link between particulate matter and cardiovascular morbidity and mortality, especially in elderly individuals (Koken, et al, 2003). Particulate matter is defined as any particle measuring less than or equal to ten micrometers (< 10 µm PM10) or two point five micrometers (< 2.5 µm PM2.5) that forms from solid particles and liquid droplets. Most particulate matter is formed due to vehicle entry, industrial processes or wood burning. Furthermore, it has also been suggested that ultrafine particulate matter measuring less than or equal to 2.5 µm is considered more harmful to health than larger particles in terms of aerodynamic diameter because PM2.5 can penetrate deeper into the lungs than to PM10 (Park, et al., 2010). Although ambient air pollution has declined in recent decades due to stringent air pollution control policies, there is little evidence to directly support the extent to which these control measures have improved public health (Tonne, et al, 2010). Investigative research has observed evidence supporting the association between air pollution and particulate matter and increased cardiovascular events. Further understanding of the mechanisms associated with these observations is needed. It is important to further examine these associations with more specific endpoints that may suggest specific pathways (Zanobetti and Schwartz, 2005). The intent of this article is to present an analytical evaluation of the data on the association of particulate matter and the incidence between cardiovascular morbidity and mortality. Methodological Issues Numerous reports have addressed the issue of time and mortality; extreme temperature factors are associated...... half of article...... heart rate variability: the Multiethnic Study of Atherosclerosis (MESA). Environment. Health perspective. 2010 October;118(10):1406-1411.4. Schneider A, Hampel R, Ibald-Mulli A, Zareba W, Schmidt G, Schneider R, et al. Changes in heart rate deceleration capacity and heart rate variability induced by air pollution in individuals with coronary heart disease. Toxic Fiber Part. 2010;7:29.5. Tonne C, Beevers S, Kelly FJ, Jarup L, Wilkinson P, Armstrong B. An approach to estimating the health effects of changes over time in air pollution: an illustration using cardio-respiratory hospital admissions in London. Occupy the Environment Med. 2010 June;67(6):422-427.6. Zanobetti A, Schwartz J. The effect of particulate air pollution on emergency hospitalizations for myocardial infarction: a multi-urban case-crossover analysis. Environment. Health perspective. 2005 August;113(8):978-982.