Differential toxicities of fine particulate matters from various sources

Abstract

Fine particulate matter less than 2.5 μm (PM2.5) in the ambient atmosphere are strongly associated with adverse health effects. However, not all PM2.5 are equally toxic, given their different sizes and chemical components. The toxicity of PM2.5 produced from various combustion sources (diesel engine, gasoline engine, biomass burning (rice straw and pine stem burning), and coal combustion) and non-combustion sources (road dust including sea spray aerosols, ammonium sulfate, and ammonium nitrate), which are known major sources of PM2.5, was determined from multiple chemical and biological responses (oxidative potential (OP), cell toxicity, genotoxicity and DNA damage, oxidative stress, and inflammatory response). Multiple biological and chemical responses for various source-specific PM2.5 were integrated to derive the toxicity scores among source-specific PM2.5. The highest toxicity score was obtained for diesel engine exhaust particles, followed in order by gasoline engine exhaust particles, particles from biomass burning, cooking aerosols, coal combustion particles, and road dust, suggesting that traffic plays a critical role in enhancing the toxic effects of PM2.5. Considering toxicity scores for source-specific PM2.5 and source fraction of ambient PM2.5, and exposure scores from ambient PM2.5 mass concentration, a new health metric (risk score) was derived, which associated more strongly with chronic obstructive pulmonary disease (COPD) mortality than the PM2.5 mass. A new health metric can be a valuable indicator to estimate the adverse health effects caused by the different PM2.5 types in the ambient atmosphere and provide practical management of PM2.5 beyond what can be achieved using only the particulate matter mass, which is the current regulation standard.