Air pollution and cardiovascular injury epidemiology, toxicology, and mechanisms.

Recent epidemiologic studies show that increased levels of air pollutants are positively associated with cardiovascular morbidity and mortality. Inhalation of air pollutants affects heart rate, heart rate variability, blood pressure, vascular tone, blood coagulability, and the progression of atherosclerosis. Several categories within the general population (i.e., people with pre-existing cardiovascular disease and diabetic and elderly individuals) are considered to be more susceptible to air pollution-mediated cardiovascular effects. Major mechanisms of inhalation-mediated cardiovascular toxicity include activation of pro-inflammatory pathways and generation of reactive oxygen species. Although most studies focus on the influence of systemic effects, recent studies indicate that ultrafine particles may be translocated into the circulation and directly transported to the vasculature and heart where they can induce cardiac arrhythmias and decrease cardiac contractility and coronary flow.