Exposure to Ambient Air PM2.5: A Significant Mechanism of Exposure to Polycyclic Aromatic Hydrocarbons for the U.S. Population

Background: To identify mechanisms between ambient air pollution exposure and human disease, air pollution studies have focused on constituents of ambient air pollution that cause adverse health effects. Polycyclic aromatic hydrocarbons (PAHs) are components of fine particulate matter (PM2.5) in ambient air pollution that may contribute to disease in populations exposed to ambient air pollution. The purpose of this study was to explore relationships between exposure to PM2.5 and body burden of PAHs in the US population. Methods: Associations between PM2.5 levels within a 5-mile radius around participants' residences on the day prior to measurement of 8 urinary PAH metabolites were investigated using a recent data linkage between the 2001-2004 NHANES and PM2.5 levels from the EPA Air Quality System database (n=744). Unadjusted and covariate-adjusted linear regression models of select PAH metabolites were found to be positively and significantly associated with PM2.5 levels within a 5-mile radius around place of residence (significant R-squared range: 0.014-0.051). Results: Geometric mean levels of urinary metabolites of pyrene were found to be 286% greater in nonsmoking subjects when PM2.5 levels around a participant's place of residence were above the 2006 National Ambient Air Quality Standards (NAAQS) cutpoint for PM2.5. Discussion: These results provide evidence of increased body burden of certain PAHs in individuals with exposure to elevated levels of PM2.5 and that people who live in areas with PM2.5 levels above the 2006 NAAQS cutpoint for PM2.5 have increased levels of pyrene at a magnitude equivalent to that of being an active tobacco smoker.