AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Effect of Sources and Chemical Aging on the Oxidative Potential of Organic Aerosol and Cellular Oxidative Stress
SHUNYAO WANG, Jianhuai Ye, Xiaomin Wang, Chow Chung-Wai, Arthur W. H. Chan, University of Toronto
Abstract Number: 617 Working Group: Linking Aerosol Oxidative Potential with Chemical Composition and Biological Endpoints
Abstract Organic aerosol (OA) accounts for a large fraction of particulate matter (PM) mass, which could induce oxidative stress once inhaled, leading to both acute and chronic cardiopulmonary outcomes. While recent epidemiological studies suggest that the chemical composition of ambient PM plays an essential role in its oxidative potential (OP), the relationship between OP and cellular generation of oxidative stress remains poorly understood. Here, we use the dithiothreitol (DTT) assay to study the OP of a wide variety of OA from field and laboratory studies, including naphthalene SOA (NSOA), phenanthrene SOA (PSOA), diesel exhaust particles, ash from the 2016 Fort McMurray wildfires, urban PM2.5 samples from India and downtown Toronto. We measured OP using the dithiothreitol (DTT) assay, and measurement of intracellular ROS production in BEAS-2B cells, a normal human airway epithelial cells. OPs and expression of inflammatory biomarkers were found to vary significantly between ambient PM from different urban areas, and between the sources. Atmospheric photochemical aging processes, including oligomerization and oxygenation, were observed to increase OP in both NSOA and PSOA systems. OP measurements were performed on chromatographically separated fractions of SOA, and SOA dimers were found to contribute significantly to DTT activity (16±3%, 40±8% for monomers, 52±10%, 56±5% for dimers, respectively for NSOA and PSOA). Further oxidation of SOA was also found to enhance the OP of NSOA. Our study provides important insights into how the chemical composition and atmospheric formation process of PM are related with its ability to cause adverse health impacts.