Abstract
BACKGROUND: Few epidemiologic studies have investigated health effects of water-soluble fractions of PM(2.5) metals, the more biologically accessible fractions of metals, in their attempt to identify health-relevant components of ambient PM(2.5). OBJECTIVES: In this study, we estimated acute cardiovascular effects of PM(2.5) components in an urban population, including a suite of water-soluble metals that are not routinely measured at the ambient level. METHODS: Ambient concentrations of criteria gases, PM(2.5), and PM(2.5) components were measured at a central monitor in Atlanta, Georgia, during 1998-2013, with some PM(2.5) components only measured during 2008-2013. In a time-series framework using Poisson regression, we estimated associations between these pollutants and daily counts of emergency department (ED) visits for cardiovascular diseases in the five-county Atlanta area. RESULTS: Among the PM(2.5) components we examined during 1998-2013, water-soluble iron had the strongest estimated effect on cardiovascular outcomes [R͡R=1.012 (95% CI: 1.005, 1.019), per interquartile range increase (20.46ng/m(3))]. The associations for PM(2.5) and other PM(2.5) components were consistent with the null when controlling for water-soluble iron. Among PM(2.5) components that were only measured during 2008-2013, water-soluble vanadium was associated with cardiovascular ED visits [R͡R=1.012 (95% CI: 1.000, 1.025), per interquartile range increase (0.19ng/m(3))]. CONCLUSIONS: Our study suggests cardiovascular effects of certain water-soluble metals, particularly water-soluble iron. The observed associations with water-soluble iron may also point to certain aspects of traffic pollution, when processed by acidifying sulfate, as a mixture harmful for cardiovascular health. https://doi.org/10.1289/EHP2182.