Abstract
Most fine ambient particulate matter (PM(2.5))-based epidemiological models use globalized concentration-response (CR) functions assuming that the toxicity of PM(2.5) is solely mass-dependent without considering its chemical composition. Although oxidative potential (OP) has emerged as an alternate metric of PM(2.5) toxicity, the association between PM(2.5) mass and OP on a large spatial extent has not been investigated. In this study, we evaluate this relationship using 385 PM(2.5) samples collected from 14 different sites across 4 different continents and using 5 different OP (and cytotoxicity) endpoints. Our results show that the relationship between PM(2.5) mass vs. OP (and cytotoxicity) is largely non-linear due to significant differences in the intrinsic toxicity, resulting from a spatially heterogeneous chemical composition of PM(2.5). These results emphasize the need to develop localized CR functions incorporating other measures of PM(2.5) properties (e.g., OP) to better predict the PM(2.5)-attributed health burdens.