Chronic Fine and Coarse Particulate Exposure, Mortality, and Coronary Heart Disease in the Nurses’ Health Study

BACKGROUND: The relationship of fine particulate matter < 2.5 microm in diameter (PM(2.5)) air pollution with mortality and cardiovascular disease is well established, with more recent long-term studies reporting larger effect sizes than earlier long-term studies. Some studies have suggested the coarse fraction, particles between 2.5 and 10 microm (PM(10-2.5)), may also be important. With respect to mortality and cardiovascular events, questions remain regarding the relative strength of effect sizes for chronic exposure to fine and coarse particles. OBJECTIVES: We examined the relationship of chronic PM(2.5) and PM(10-2.5) exposures with all-cause mortality and fatal and nonfatal incident coronary heart disease (CHD), adjusting for time-varying covariates. METHODS: The current study included women from the Nurses' Health Study living in metropolitan areas of the northeastern and midwestern United States. Follow-up was from 1992 to 2002. We used geographic information systems-based spatial smoothing models to estimate monthly exposures at each participant's residence. RESULTS: We found increased risk of all-cause mortality hazard ratio (HR), 1.26; 95% confidence interval (CI), 1.02-1.54 and fatal CHD (HR = 2.02; 95% CI, 1.07-3.78) associated with each 10-microg/m(3) increase in annual PM(2.5) exposure. The association between fatal CHD and PM(10-2.5) was weaker. CONCLUSIONS: Our findings contribute to growing evidence that chronic PM(2.5) exposure is associated with risk of all-cause and cardiovascular mortality.