Impact of Wildfires on the Oxidative Potential of Ambient Aerosol

BRADLEY ISENOR, Arthur W. H. Chan, University of Toronto

     Abstract Number: 104
     Working Group: Health-Related Aerosols

Abstract
Wildfire activity is predicted to increase over time, potentially increasing adverse health impacts due to elevated levels of fine particulate matter (PM_2.5). Elevated PM_2.5 attributed to wildfires pose a more serious problem when coupled with recent evidence that wildfire-PM_2.5 may be more toxic on a per mass basis than common forms of ambient PM_2.5 (e.g., traffic and industrial PM_2.5). For these reasons, it is necessary that wildfire-PM_2.5 and their health effects are understood; however, few studies have directly assessed the potential toxicity of wildfire-PM_2.5. Here we study the toxicity of both wildfire and non-wildfire-PM_2.5 through the lens of their oxidative potentials (OP; i.e., the ability to generate reactive oxygen species and induce oxidative stress). To assess the OP of our samples, we employ the dithiothreitol assay to measure antioxidant depletion. Alongside this assay, electron paramagnetic resonance spectroscopy is used with spin-trapping agents to identify and quantify harmful reactive oxygen species that may be generated when particulate deposits in the lungs. Ambient aerosol samples were collected at an urban site (Toronto, ON) and a remote site (East Trout Lake, SK) over 2023 with wildfire influence coming from the North American wildfires of that year. Given the location and separation of the 2 sites, they are predicted to have considerably different compositions and thus different OP due to differing sources and aging times of wildfire-PM_2.5. In this presentation, an analysis of OP data from samples that were collected at both sites will be presented with an emphasis on how the OP of PM_2.5 samples are impacted by elevated levels of biomass burning aerosol attributed to wildfires. Results from this work will improve understanding of how potential toxicity of PM is related to their sources and atmospheric evolution.