AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Oxidative Potential of Particulate Matter and Generation of Reactive Oxygen Species in the Epithelial Lining Fluid
TING FANG, Pascale Lakey, Rodney J. Weber, Manabu Shiraiwa, University of California, Irvine
Abstract Number: 573 Working Group: Health-Related Aerosols
Abstract Reactive oxygen species (ROS) play a central role in oxidative stress and possibly adverse health effects of atmospheric particulate matter (PM). Respiratory particle deposition can lead to the release of ROS in the epithelial lining fluid (ELF) due to catalytic reactions of PM redox-active components including soluble transition metal ions and organic compounds with lung antioxidants. Ambient particles with aerodynamic diameters below 2.5 μm as well as size-segregated particles (from 56 nm to 18 μm) were collected in Atlanta. Organic carbon and water-soluble metals were measured and PM oxidative potential was quantified with the dithiothreitol (DTT) and ascorbic acid assays. The kinetic multi-layer model of surface and bulk chemistry in the ELF combined with a human respiratory tract model was applied to estimate the concentrations and production rates of ROS by redox reactions of PM components. The extrathoracic region was found to have higher ROS concentrations compared to the bronchial and alveolar regions due to higher particle deposition into the ELF with lower ELF volume. Fe and Cu ions contribute mainly to H2O2 and O2- production rates, which show strong correlation with measured oxidative potential. In contrast, oxidative potential does not exhibit significant correlations with OH production rates, which are mainly driven by decomposition of secondary organic aerosols and Fenton(-like) reactions of metal ions. Oxidative potential is a good indicator of production of H2O2 and O2-, but does not represent OH generation in the ELF. Combination of field measurements of chemical composition and oxidative potential with model simulations can provide critical insights into ROS formation by ambient PM in the human respiratory tract.