Long-term exposure to fine particle components and mortality in the Southeastern US

Abstract

BACKGROUND AND AIM: Long-term exposure to fine particulate matter (PM2.5) has been associated with adverse health effects. However, health effects of PM2.5 components have been less studied. METHODS: We performed a population-based cohort study, comprising all Medicare enrollees (aged ≥65, N=13,590,387) in the southeastern US from 2000-2016. Based on well-validated prediction models at 1-km resolution, we estimated ZIP Code-level annual mean concentrations for five major PM2.5 components, including black carbon (BC), nitrate (NIT), organic matter (OM), sulfate (SO4), and soil particles. Cox proportional hazards models were fit to examine the association between each PM2.5 major component and all-cause mortality, adjusting for potential confounders. RESULTS:In single pollutant models, all five major PM2.5 components were statistically significantly associated with all-cause mortality. In multi-pollutant models that included all five major components simultaneously, we observed statistically significant associations with long-term exposure to BC, OM, NIT, and soil particle, and the hazard ratios (HR) per interquartile range (IQR) increases in exposure were 1.023 (95% CI:1.019-1.027), 1.004 (95%CI:1.001-1.007). 1.013 (95%CI: 1.012-1.015), and 1.003 (95% CI: 1.001-1.004). However, with adjustment of other PM2.5 components, SO4 was not associated with increased mortality, with a HR of 0.995 (95%CI: 0.992-0.998). CONCLUSIONS:Our study provides epidemiological evidence that long-term exposure to major PM2.5 components, including BC, OM, NIT, and soil particle, was significantly associated with elevated mortality. KEYWORDS: Air pollution, PM2.5 components, all-cause mortality, survival analysis