The Influence of Meteorological Conditions on Traffic-related SOA Formation and Its Relationship with OP

LI-TI CHOU, Po-Kai Chang, Ta-Chih Hsiao, National Taiwan University, Taiwan

     Abstract Number: 338
     Working Group: Health-Related Aerosols

Abstract
Oxidative potential (OP), defined as a measure of PM's capacity to oxidize target molecules through the generation of reactive oxygen species (ROS), has been commonly used to reflect the toxicity of particulate matter (PM) in recent studies. The formation of secondary organic aerosol (SOA) from radicals reacting with volatile organic compounds (VOCs) has raised significant concerns due to its effects on human health and climate change. In Southeast Asia, vehicle emissions containing abundant VOCs are one of the important sources leading to SOA formation in urban areas. Studies have shown that atmospheric processes can trigger PM's redox reactions and promote SOA formation, thereby influencing OP. However, most related studies have focused on conducting such research in the laboratory. This study uses a homemade oxidation flow reactor (OFR) to mimic the atmospheric environment. To accurately assess public exposure to traffic-related SOA, the OFR is set up in a near-road monitoring station, integrating several field instruments including the scanning mobility particle sizer (SMPS), aerodynamic particle sizer (APS), aethalometer, aerosol chemical speciation monitor (ACSM), etc. For the determination of OP, the DTT assay has been chosen solely because it is most relevant to health outcomes and responsive to several chemical species. Our aim is to investigate the impact of SOA formation from traffic emissions on OP under different meteorological conditions, such as temperature, relative humidity, solar irradiance, etc. Additionally, we will explore the detailed physical and chemical transformations of particles through atmospheric reactions simultaneously.