Abstract View
Characterization and Comparison of PM2.5 Oxidative Potential Assessed by Two Acellular Assays
DONG GAO, Krystal Godri Pollitt, James Mulholland, Armistead G. Russell, Rodney J. Weber, Georgia Institute of Technology
Abstract Number: 513
Working Group: Health-Related Aerosols
Abstract
The capability of ambient particles to generate in vivo reactive oxygen species (ROS), known as oxidative potential (OP), is a potential metric for evaluating the health effects of particulate matter (PM) and is supported by several recent epidemiological investigations. A variety of acellular assays have been developed to assess PM OP. In this study, we systematically compared two health-relevant acellular OP assays that track the depletion of antioxidants or reductant surrogates: the synthetic respiratory tract lining fluid (RTLF) assay that tracks the depletion of ascorbic acid (AA) and glutathione (GSH), and the dithiothreitol (DTT) assay that tracks the depletion of DTT. Year-long daily samples were collected at an urban site in Atlanta, GA during 2017, and both DTT and RTLF assays were performed to measure the OP of water-soluble PM2.5 components. PM2.5 mass and major chemical components, including metals, ions, and organic and elemental carbon were also analyzed. The results showed that the OP assays differ in their sensitivities to PM chemical components. OP as measured by the DTT and AA depletion (OPDTT and OPAA, respectively) were correlated with both organics and some water-soluble metal species, whereas that from the GSH depletion (OPGSH) was exclusively sensitive to water-soluble Cu. These OP assays were moderately correlated with each other due to the common contribution from metal ions. Multivariate linear regression models were developed to predict OP measures from the particle composition data. Variability in OPDTT and OPAA were attributed to not only the concentrations of metal ions (mainly Fe and Cu) and organic compounds, but also antagonistic metal–organic and metal–metal interactions. OPGSH was sensitive to the change in water-soluble Cu and brown carbon (BrC), a proxy for ambient humic-like substances.