Secondary Organic Aerosol from Anthropogenic Terpenes and Terpenoids and Contributions to Air Quality in United States Cities
Masoud Akbarzadeh, Huiying Luo, Abraham Dearden, Havala Pye, Lauren A. Garofalo, Delphine K. Farmer, Tucker Melles, Cort Zang, Megan Willis, Matthew Coggon, Carsten Warneke, Damien Ketcherside, Lu Hu, Nga Lee Ng, James Hurley, Gabriel Isaacman-VanWertz, Benjamin Murphy, SHANTANU JATHAR, Colorado State University
Abstract Number: 599
Working Group: Chemicals of Emerging Concern in Indoor and Outdoor Aerosol: Sources, Vectors, Reactivity, and Impacts
Abstract
Volatile chemical product (VCP) use results in volatile organic compound (VOC) emissions that contribute to the formation of ozone (O3) and secondary organic aerosol (SOA) and negatively affect urban air quality. Personal care products and cleaning agents are formulated with fragrant hydrocarbon terpenes (e.g., limonene) and oxygenated terpenes (e.g., linalool), which once released, participate in photochemical reactions to form O3 and SOA. In this work, we combine environmental chamber data and box and chemical transport models to study how VCP terpenes contribute to SOA formation and the urban organic aerosol (OA) burden in United States (US) cities. Consistent with earlier work, our chamber and modeling data suggested that while cyclic terpenes like limonene and α-pinene are efficient SOA precursors (mass yields >20%) , most acyclic (e.g., linalool) and oxygenated (e.g., α-terpineol) terpenes have a much weaker potential (mass yields <5%) to form SOA. Simulations were performed with the Community Multiscale Air Quality (CMAQ) model over the contiguous US for the summer of 2023 and these indicated that terpenes contributed up to 20% of the SOA from all VCP VOCs in urban areas. We also found that VCP and mobile sources were both responsible for similar contributions to urban OA in the top 20 metropolitan statistical areas in the US and, together, they accounted for ~1 µg m-3 of OA and up to 25% of the total OA in those urban areas. Our work highlights the influence of anthropogenic terpenes on urban air quality and advocates for revisiting VCP formulations where fragrant terpenes could be removed or substituted to reduce anthropogenic contributions to urban PM2.5.