AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Chemical and Cellular Oxidant Production Induced by Naphthalene Secondary Organic Aerosol (SOA) Formed in the Presence of Iron Sulfate
WING-YIN TUET, Yunle Chen, Shierly Fok, Rodney J. Weber, Julie Champion, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 231 Working Group: Linking Aerosol Oxidative Potential with Chemical Composition and Biological Endpoints
Abstract Results from 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 detrimental health effects. Secondary organic aerosols (SOA) constitute a significant portion of PM, and recent health studies have shown that SOA exposure induces inflammatory responses. The effect of redox-active metals on SOA health effects, however, have not been considered.
Here, we present oxidative potential and ROS/RNS measurements from laboratory-generated naphthalene SOA formed in the presence of inorganic (ammonium sulfate, AS) and metal-containing inorganic (iron sulfate, FS) seed. Naphthalene was chosen as it has previously been shown to have the highest oxidative potential and induce high levels of ROS/RNS among different types of SOA. All chamber experiments were conducted under humid conditions in the presence of NO using H2O2 as the hydroxyl radical precursor. Alveolar macrophages were exposed to SOA samples and ROS/RNS production was measured post-exposure. Similarly, dithiothreitol (DTT) was used to assess the oxidative potential of SOA. Experiments were conducted with different initial naphthalene concentrations to evaluate whether the degree of oxidation affected health effects. In general, exposure to FS seeded SOA resulted in higher ROS/RNS levels compared to AS seeded SOA, although this is likely due to differences in oxidation state as a positive exponential correlation was observed between ROS/RNS levels and average carbon oxidation state (OS) for both AS and FS seeded SOA. No trends were observed for DTT activity, consistent with previous studies. Finally, multiple filters were collected from a single experiment to investigate the effect of aging. The results also followed the ROS/RNS vs. OS trend observed in this study. Together these results have significant implications for future health studies as atmospheric aging leads to increases in oxidation, which may affect cellular responses.