Several epidemiological studies have demonstrated a consistent statistical association between cardiovascular disease and air pollution exposure. In this review we describe the nature of the most common ambient-air pollutants (either gaseous or particulate of different size); then, we examine the pathophysiological pathways linking the air pollutants with their cardiovascular effects (arterial vasoconstriction, systemic inflammatory response, enhanced thrombosis, a propensity for arrhythmia). A comprehensive review of the literature on air pollution and the rate of hospital admission, morbidity, and mortality due to cardiovascular reasons are also provided. In the last section, we review the most recent studies that have outlined the correlation between the onset of acute myocardial infarction and the level of outdoor air pollution. In conclusion, scientific evidence is growing in support of the hypothesis that ambient air pollution acts as a risk factor for cardiovascular disease, and may trigger the onset of acute myocardial infarction.