According to this study:

* Long-term exposure to fine particulate air pollution increases the risk of cardiovascular and cerebrovascular events in postmenopausal women.

Long-term pollution exposure is known to increase the risk of cardiovascular disease. This study evaluated the effect of long-term exposure to fine particulate air pollution on cardiovascular disease in 65,893 postmenopausal women between the ages of 50 and 79 enrolled in the Women's Health Initiative between 1994 and 1998. Participants had not been previously diagnosed with cardiovascular disease.

Air pollution data were obtained from the Environmental Protection Agency's Aerometric Information Retrieval System. The study focused on exposure to particulate matter (PM) of less than 2.5 micromoles in aerodynamic diameter (PM_2.5).

Annual questionnaires and medical records were used to identify a cardiovascular event, including myocardial infarction, coronary revascularization, stroke, and death from either heart disease or cerebrovascular disease. Data were adjusted for factors such as body mass index and smoking status.

A total of 58,610 women were included in the main analyses: most were white (83.1%) and were a median age of 63 years at the time of enrollment. More than 85% of them had resided in their current state for 20 years or longer. Their demographic and lifestyle characteristics were similar across levels of exposure to PM_2.5.

Three percent, or 1,816, of the women had one or more cardiovascular events during the study. Each increase of 10 micrograms per cubic meter in PM_2.5 level was "associated with a 24% increase in the risk of a [first] cardiovascular event [horizontal ellipsis] and a 76% increase in the risk of death from cardiovascular disease," including coronary heart disease and cerebrovascular disease. Each increase of 10 micrograms per cubic meter in PM_2.5 level also increased the risk of cerebrovascular events and death from a cerebrovascular cause by 35% and 83%, respectively.

Although the mechanism operating behind the increase in cardiovascular disease with long-term exposure to particulate matter air pollution is still unclear, this study confirms the link identified in previous reports. In addition, the authors state that their results indicate that "the magnitude of health effects [from PM] may be larger than previously recognized."