Secondary Organic Aerosol (SOA) from Naphthalene Oxidation by Hydroxyl (OH) and Nitrate (NO3) radicals: Formation Pathways, Light Absorption, and Oxidative Potential

Particulate matter (PM) has tremendous impacts on global climate and human health, and remains as one of the most important environmental issues in urban environments. With stringent control on direct emissions of PM in many countries, secondary aerosol from oxidation of volatile organic compounds (VOCs), termed as secondary organic aerosol (SOA), becomes an important source of PM. Their effects on health (i.e., toxicity) and climate (i.e., absorptivity), however, have not been well characterized. In urban areas, aromatic VOCs can lead to substantial SOA formation, thereby influencing the air quality and regional climate. The SOA formation and their environmental impacts of the light aromatics (e.g., single-ring) have been widely studied, but those of the heavy ones (e.g., double-ring) have not. In this study, we plan to use an oxidative flow reactor (OFR) coupled with online and offline chemical measurements, as well as acellular assays and light-absorption measurements, to study the health and climate effects of SOA from oxidation of naphthalene, as a representative heavy aromatic VOC. Experiments will be conducted with hydroxyl (OH) and nitrate (NO3) radical oxidation to represent daytime and nighttime chemistry, respectively. The results obtained will help in model simulation on the environmental impacts of this overlooked class of SOA precursors, and in policy making to mitigate the health and climate effects of SOA.  Duration = 6 months

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