GENERAL CARDIOLOGY

Air pollution and cardiovascular risk in women ▸

Air pollution has previously been linked to an increased risk of cardiovascular disease. However the mechanism by which this occurs, the magnitude of the association, and the effects of long-term exposure to pollutants remain to be elucidated.

The Women’s Health Initiative (WHI) was an observational study of 65 893 post menopausal women in 36 US metropolitan areas that ran from 1994 to 1998 with a median follow-up of 6 years. None of the women recruited had any previous history of cardiovascular disease. Data on air pollution in the cities studied was obtained from the Environmental Protection Agency’s Aerometric Information Retrieval System. Each woman’s individual exposure to air pollution was estimated by using the monitor closest to their residence. Hazard ratios were estimated for a first cardiovascular event (myocardial infarction, coronary revascularisation, stroke and death from coronary or cerebrovascular disease), adjusting for age, race or ethnic group, smoking status, educational level, household income, body mass index, presence or absence of diabetes, hypertension and hypercholesterolaemia.

Overall 1816 women had one or more fatal or non-fatal cardiovascular events during the four year period of the study. Each increase of 10 μg per cubic metre in levels of particulate matter of less than 2.5 μm in aerodynamic diameter (PM_2.5) was associated with a 24% increase in the risk of a cardiovascular event (hazard ratio (HR), 1.24; 95% confidence interval (CI), 1.09 to 1.41) and a 76% increase in the risk of death from cardiovascular disease (HR, 1.76; 95% CI, 1.25 to 2.47). Risk of cerebrovascular events was also associated with increased levels of PM_2.5 (HR, 1.35; 95% CI, 1.08 to 1.68).

The exact mechanisms by which fine particulate air pollution exacerbates cardiovascular risk remain to be elucidated. Data show that inhalation of particulate air pollution creates and exacerbates both pulmonary and systemic …