Air pollution and emergency admissions in Boston, MA

Study Objective: Many studies have shown that ambient particulate air pollution (PM) is associated with increased risk of hospital admissions and deaths for cardiovascular or respiratory causes around the world. In general these have been analysed in association with PM10 and ozone, whereas PM2.5 is now the particle measure of greatest health and regulatory concern. And little has been published on associations of hospital admissions and PM components. Design: This study analysed hospital admissions for myocardial infarction (15 578 patients), and pneumonia (24 857 patients) in associations with fine particulate air pollution, black carbon (BC), ozone, nitrogen dioxide (NO2), PM not from traffic, and carbon monoxide (CO) in the greater Boston area for the years 1995-1999 using a case-crossover analysis, with control days matched on temperature. Main results: A significant association was found between NO2 (12.7% change (95% CI: 5.8, 18)), PM2.5 (8.6% increase (95% CI: 1.2, 15.4)), and BC (8.3% increase (95% CI: 0.2, 15.8)) and the risk of emergency myocardial infarction hospitalisation; and between BC (11.7% increase (95% CI: 4.8, 17.4)), PM2.5 (6.5% increase (95% CI: 1.1, 11.4)), and CO (5.5% increase (95% CI: 1.1, 9.5)) and the risk of pneumonia hospitalisation. Conclusions: The pattern of associations seen for myocardial infarction and pneumonia (strongest associations with NO2, CO, and BC) suggests that traffic exposure is primarily responsible for the association with heart attacks.