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Comparing the Toxicity and Composition of Particulate in Multiple Canadian Air Zones
DANA UMBRIO, Alison Traub, Cheol H. Jeong, Scott Weichenthal, Hongyu You, Ryan Kulka, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 333
Working Group: Health-Related Aerosols
Abstract
Exposure to ambient fine particulate matter (PM2.5) has been linked to adverse respiratory and cardiovascular health outcomes. In Canada, PM2.5 is regulated by its mass concentration, but this does not adequately capture how differences in its composition or origins may influence associated health risks. PM2.5 is postulated to initiate some adverse health-effects by generating reactive oxygen species when inhaled, which leads to oxidative stress and inflammatory responses. Oxidative potential (OP) and oxidative burden (OB) are thus being explored as more health-relevant metrics for assessing the risk of particulate matter. These metrics have already been shown to be associated with a range of health outcomes. Moreover, correlations with different metals have also been reported, although the findings are often conflicting, and thus not readily generalizable across locations or airshed.
Approximately 1000 samples, collected from June 2016 until December 2018 in forty cities across Canada, were analyzed using three standardized acellular assays: ascorbate (AA), glutathione (GSH) and dithiothreitol (DTT). These assays measured the rate of depletion of AA, GSH and DTT when exposed to PM2.5 samples. Linear and multilinear correlation analyses were used to evaluate how PM2.5 metal composition influenced OP and OB and how these relationships differed in six air zones across Canada. Moreover, cluster analysis was applied to classify the metals into source-related groups and identify marker metals. These findings will be discussed in terms of how the associations of OP and OB with composition and sources can be generalised across a large geographic area.