Particulate matter (PM) air pollution is associated with an increased risk of cardiovascular morbidity and mortality. The focus of this review will be on the role that both acute and chronic exposure to PM plays in causing cardiovascular disease and on the latest major new findings and controversies in this field of research. Even short-term exposure to PM2.5 over a few hours can trigger myocardial infarctions, cardiac ischemia, arrhythmias, heart failure, stroke, exacerbation of peripheral arterial disease, and sudden death. Chronic exposure to moderately elevated levels also enhances the risk for developing a variety of cardiovascular diseases, possibly including hypertension and systemic atherosclerosis. Recent epidemiologic studies have furthered our understanding of the linkage between air pollutants and human health, with a multitude of plausible mechanistic explanations having been demonstrated experimentally during the past few years. Although a number of finer details relating to both the epidemiology and the mechanisms involved require more investigation, the overall weight of evidence is now sufficient to implicate PM exposure as a cause of cardiovascular disease. Without doubt, exposure to particulate matter can play a causal role in triggering a host of acute cardiovascular events via many mechanisms. Although long-term air pollution exposure has been shown to promote the development of atherosclerosis, the clinical significance of this relation requires more investigation.