The Association Between Air Pollution and Human Health

Abstract

Air pollution is a risk factor of multiple adverse health outcomes. I and my colleagues investigated the health effect of long-term and short-term exposures to air pollution in the entire Medicare population. We were interested in the effect of air pollution below the current National Ambient Air Quality Standards (NAAQS) set by the U.S. Environmental Protection Agency (EPA). We also identified subgroups that were particularly vulnerable to air pollution. We first developed air pollution models to predict daily and annual exposures to fine particulate matter (particles with aerodynamic diameter less than 2.5 µm, or PM2.5) and ozone among Medicare population with high accuracy (R2 = 0.84 for PM2.5 and R2 = 0.76 for ozone). For long-term exposures to air pollution, we found that increases of 10 μg/m3 in PM2.5 and of 10 ppb in ozone were associated with increases in all-cause mortality of 7.3% (95% confidence interval [CI], 7.1 - 7.5) and 1.1% (95% CI, 1.0 - 1.2), respectively. The association was still significant when restricting to PM2.5 below 12 μg/m3 (the annual standard set by EPA) and ozone below 50 ppb. The risk of mortality was higher among male, African Americans and people of low income than the general population. For short-term exposures to air pollution, increase of 10 μg/m3 in daily PM2.5 and 10 ppb in daily ozone were significantly associated with increases in daily all-cause mortality of 1.05% (95% CI, 0.95 - 1.15) and 0.51% (95% CI, 0.41 - 0.61), respectively. When restricting to the analysis below 25 μg/m3 and 60 ppb, lower than the current daily standards set by EPA, the significant association remained. In conclusion, exposures to air pollution are associated with mortality both in the long-term and short-term, even below the current national standards, providing strong evidence that these national air quality standards need to be reevaluated. Some subgroups, such as African Americans and people of low income, are more vulnerable to air pollution than the general population.