Understanding the sources, atmospheric processes, health associations and size distribution of aerosol oxidative potential

Abstract

Aerosol oxidative potential (OP), the ability of particulate matter (PM) to generate reactive oxygen species (ROS) or deplete antioxidants in vivo, plays an important role in upsetting redox homeostasis, causing oxidative stress, and leading to adverse health effects. This dissertation presents a semi-automated system for quantifying OP using two widely used chemical measures, the dithiothreitol (DTT) and ascorbic acid (AA) assays, from aqueous extracts of ambient PM samples. The system was used to generate large dataset at urban, rural, road-side sites in southeast U.S. to investigate the spatiotemporal distributions, sources, atmospheric processes, and health associations of water-soluble OP^DTT and OP^AA of fine particles (PM2.5, with aerodynamic diameter smaller than 2.5 µm) as part of the Southeastern Center for Air Pollution & Epidemiology (SCAPE) project. Ambient size distributions of water-soluble OP^DTT and OP^AA at an urban and a road-side site collected using Micro-Orifice Uniform Deposit Impactors (MOUDIs) were consistent with the sources and atmospheric processes for both forms of OP from the SCAPE study. Ambient size distribution of water-insoluble fractions of OP^DTT at the urban and road-side site was also measured and compared to water-soluble OP^DTT in terms of major players, atmospheric processes, and deposition in the human respiratory system.