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Effect of the COVID-19 Pandemic on Aerosol Composition in Atlanta, GA
JEAN RIVERA-RIOS, Taekyu Joo, Tianchang Xu, Masayuki Takeuchi, Chris Peng, Leah Williams, Philip Croteau, John Jayne, Jennifer Kaiser, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 582
Working Group: Urban Aerosols
Abstract
The COVID-19 pandemic led to drastic changes in human behavior across the United States. Lockdowns caused reductions in anthropogenic activities, including reduced traffic and the closure of businesses like bars and restaurants. Atlanta, GA, is an urban environment surrounded by sources of biogenic emissions. Air quality in Atlanta is modulated by the interplay between anthropogenic and biogenic emissions. We performed field measurements during the summer and fall/winter of 2020 in order to evaluate the effects of the COVID-19 pandemic related behavioral changes on air quality in Atlanta. Measurements include, O3, nitrogen oxides (NO, NO2), volatile organic compounds (VOCs), PM1 volume and number concentration and non-refractory PM1 particle composition. The organic aerosol (OA) composition, using data from a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Time-of-Flight Aerosol Chemical Speciation Monitor (TOF-ACSM), was source apportioned with positive matrix factorization (PMF). The resolved factors have been previously observed in Atlanta. Secondary factors include more-oxidized oxygenated organic aerosol (MO-OOA), less-oxidized OOA (LO-OOA), and isoprene aerosol (Isop-OA). Primary/anthropogenic factors include hydrocarbon-like OA (HOA), cooking OA (COA) and biomass-burning OA (BBOA). The months of April and May had the lowest amount of traffic relative to previous years. Changes to O3 during those months include higher overall overnight concentrations and lower daily maximums. Changes to secondary OA (SOA) composition include reductions in the mass fraction of MO-OOA. This aerosol subtype is replaced by a different one, a LO-OOA-like factor (LO-OOA2) that behaves differently from the one we typically observe in Atlanta, LO-OOA1, which is also observed. Other changes include reductions in the frequency and intensity of COA enhancements during the low-traffic months, indicating that other types of anthropogenic activities were also impacted and had effects on SOA composition. Measurements in Atlanta allow us to examine the effects of anthropogenic emission reductions on SOA from biogenic sources.