AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Chemical and Cellular Oxidant Production from Secondary Organic Aerosols (SOA) Generated from the Photooxidation of Volatile Organic Compounds
WING-YIN TUET, Yunle Chen, Shierly Fok, Rodney J. Weber, Julie Champion, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 397 Working Group: Health Related Aerosols
Abstract Results from epidemiology studies have found associations between elevated particulate matter (PM) concentrations and increased incidences of cardiopulmonary disease. Toxicology studies suggest that PM-induced oxidant production, including reactive oxygen and nitrogen species (ROS/RNS), may be a possible mechanism by which PM exposure results in adverse health end points. Here, we present chemical and cellular measurements of ROS/RNS from SOA formed from the photooxidation of six commonly emitted volatile organic compounds (VOCs). Photo-oxidation experiments were conducted in the Georgia Tech Environmental (GTEC) facility under both dry and humid conditions in the presence of ammonium sulfate seed. H2O2 was used as an OH radical precursor. Compounds were chosen to represent the main classes of hydrocarbons found in biogenic and anthropogenic emissions. Filter samples were collected at the end of each experiment. Murine alveolar macrophages were used to measure intracellular ROS/RNS production, while dithiothreitol (DTT) was used to measure the concentration of redox-active species. Intracellular ROS/RNS was characterized using response parameters obtained by fitting dose-response data using the Hill equation. These response parameters (maximum response, EC50, Hill slope, threshold, and area under the dose-response curve) were compared with the concentration of redox-active species as measured by DTT activity to determine whether chemical assays were representative of cellular response. We found that SOA generated from different precursor VOCs contained different concentrations of redox-active species as measured by DTT and induced different levels of cellular ROS/RNS. In particular, SOA generated from naphthalene produced the highest DTT activity and ROS/RNS production. These results will also be discussed in the context of aerosol chemical composition and properties.