Chemical Composition and Oxidative Potential Analysis of Inhalable Road Dust in Toronto

Abstract

In many cities, traffic combustion emissions are decreasing as a result of more stringent emissions standards and resulting technological improvements. However, non-tailpipe emissions have been neglect and their relative contribution to total traffic-related particle emissions is expected to increase in the upcoming years. The chemical composition of non-tailpipe particulate matter has been reasonably well established. However, too little is known about the toxicity of non-tailpipe emissions and the road dust they produce. Road dust contains a mixture of particles from several sources such as road surface wear, soil, tire wear, and brake wear. It can be resuspended by wind or traffic turbulence and thereby pose a threat to public health.This presentation will focus on the relationship between inferred toxicity and the chemical composition of inhalable road dust (PM2.5 and PM10) from different districts within Toronto. Road dust was collected from residential roads, highways, arterial roads, underground parking garages, ground parking area, and urban background sites. Size-resolved inhalable road dust samples were resuspended onto filters through a custom-built apparatus. The oxidative potential of PM2.5 and PM10 in road dust is being determined with the acellular dithiothreitol assay to infer toxicity. The metal and organic composition of PM2.5 and PM10 in road dust are being determined and source apportionment will be performed to link the inferred toxicity back to specific sources. This work will improve our understanding about the toxicity of non-tailpipe emissions, and also give deeper insights into the relationships between the oxidative potential of road dust, its chemical composition and its contributing sources.