Associations between ambient PM2.5 – components and age-specific mortality risk in the United States

Abstract

Long-term exposure to fine particulate matter (PM 2.5 ) has been associated with premature mortality, but less work has examined associations with multiple PM 2.5 components. In this study we assess the relationship between specific PM 2.5 components (black carbon (BC), organic matter (OM), sulfate (SO 4 ), nitrate (NO 3 ), ammonium (NH 4 ), soil, and seasalt) and mean age-specific mortality risk (ASMR) between 2010 and 2015 at the census tract (CT) level from the US Small-Area Life Expectancy Estimates Project using multilevel models that control for a rich set of socioeconomic factors (SES) and weather conditions. We observed that ASMR and PM-components varied substantially across the US CTs. CTs accounted for the majority of the total variability in ASMR (∼75-95%). Much of the variation in ASMR observed at the state and county level were explained by SES (∼70-90%) and PM 2.5 -component concentrations (∼ 20-50%). Underprivileged CTs (CTs with a high proportion of Black residents, residents living in poverty, foreign-born residents, residents with no college education) had higher PM 2.5 and PM 2.5 -component concentrations. We observed significant associations between PM 2.5 -components, OM, SO 4 , soil and seasalt, in fully adjusted models with ASMR for most age groups > 25 years and older, with the highest associations observed for OM and ASMR across most age groups. The strongest associations between PM 2.5 -components and ASMR were observed for older residents (65-74 years of age). The associations detected were highest in underprivileged CTs. Our findings support that the impact of PM 2.5 on the risk of mortality, likely varies by particle composition.