Mortality risk and PM2.5 air pollution in the USA: an analysis of a national prospective cohort

Epidemiologic evidence indicates that exposure to fine particulate matter air pollution (PM2.5) contributes to global burden of disease, primarily because of increased risk of cardiovascular morbidity and mortality. This study evaluates associations between long-term PM2.5 exposure and mortality risk in national, representative cohorts of the US adult population, constructed from public-use National Health Interview Survey (NHIS) data. Two cohorts consisting of 392,807 and 162,373 individuals (without and with individual smoking data) were compiled from public-use NHIS survey data (1986-2001) with mortality linkage through 2011. Cohorts included persons who lived in a metropolitan statistical area (MSA) were 18-84 years of age and had individual risk factor information. Modeled PM2.5 exposures were assigned as MSA-level mean ambient concentration for 1999 through 2008. Mortality hazard ratios (HRs) were estimated using Cox proportional hazard regression models, controlling for age, race, sex, income, marital status, education, body mass index, and smoking status. Estimated HRs for all-cause and cardiovascular mortality, associated with a 10-mu g/m(3) exposure increment of PM2.5 were 1.06 (1.01-1.11) and 1.34 (1.21-1.48), respectively, in models that controlled for various individual risk factors, including smoking. This study provides evidence that elevated risks of mortality, especially cardiovascular disease mortality, are associated with long-term exposure to PM2.5 air pollution in US nationwide adult cohorts constructed from public-use NHIS data.