Evaluating the Effects of Ambient Air Pollution on Life Expectancy

Abstract

Air pollution is an important determinant of population health. In this issue of the Journal, Pope et al.¹ provide data that once again reinforce this fundamental concept. In an analysis that correlates reductions in fine particulate matter (i.e., particles less than 2.5 μm in aerodynamic diameter, or PM_2.5) in the air with life expectancies, the investigators found that a decrease in the concentration of PM_2.5 of 10 μg per cubic meter is associated with an increase in life expectancy of 0.77 year. Their analysis is based on correlating reductions in particulate air pollution over the past several decades with increases in life expectancy in 217 counties in 51 metropolitan areas in the United States. Although ecologic in nature (i.e., reflecting associations between air pollution and life expectancy at the county rather than the individual level), these results appear to be robust with respect to adjustment for changes in socioeconomic, demographic, and smoking patterns occurring over the same period.