AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Chemical Oxidant Production and Cellular Inflammatory Response from Secondary Organic Aerosols (SOA) Generated from the Photooxidation of Biogenic and Anthropogenic Precursors
WING-YIN TUET, Shierly Fok, Yunle Chen, Rodney J. Weber, Julie Champion, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 229 Working Group: Linking Aerosol Oxidative Potential with Chemical Composition and Biological Endpoints
Abstract Exposure to particulate matter (PM) is a leading global health risk, with multiple epidemiological studies reporting associations between elevated PM concentrations and cardiopulmonary incidences. Prior health studies have focused on the health effects of primary aerosols even though field measurements have repeatedly shown that secondary organic aerosols (SOA) often dominate, even in urban centers. A proposed mechanism by which PM exposure results in detrimental health effects is PM-induced oxidant production, including reactive oxygen and nitrogen species (ROS/RNS). These species are known to induce inflammatory cascades, thus resulting in oxidative stress and cellular damage.
Here, we present chemical and cellular measurements from laboratory-generated chamber SOA formed from the photooxidation of six common precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different conditions (RO2 + HO2 vs. RO2 + NO dominant, dry vs. humid). Compounds were chosen to represent major classes of hydrocarbons found in biogenic and anthropogenic emissions. Murine alveolar macrophages were exposed to SOA samples for 24 hrs and the resulting ROS/RNS production and cytokine (TNF-α and IL-6) secretion was measured. Dithiothreitol (DTT) was also utilized to measure the concentration of redox-active species present in each SOA sample. The intrinsic DTT activity for all SOA systems investigated was found to be highly dependent on SOA precursor, with isoprene and naphthalene SOA generating the lowest and highest DTT activity, respectively. Furthermore, distinct cellular response patterns were observed for SOA systems whose photooxidation products shared similar chemical functionalities and structures. A positive nonlinear correlation was also observed between ROS/RNS levels and DTT activity. Finally, in the context of ambient samples collected during summer and winter in the greater Atlanta area, all laboratory-generated SOA produced similar or higher levels of ROS/RNS and DTT activities, suggesting that the health effects of SOA are important considerations for understanding the health implications of ambient aerosols.