AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Impact of Fireworks, Residential Wood Burning, and Wildfire on PM2.5 Concentrations in Southern California
XIANG LI, Melissa Sheffer, Mark Bassett, Scott A. Epstein, South Coast Air Quality Management District
Abstract Number: 719 Working Group: Urban Aerosols
Abstract The South Coast Air Basin (SCAB), which includes the Los Angeles metropolitan area and surrounding suburban areas, is home to approximately 17 million people and is considered one of the most polluted regions in the nation. Although PM2.5 concentrations in the SCAB have dropped significantly over the past two decades, high pollution events such as Independence Day fireworks, residential wood burning during Christmas and New Year holidays, and wildfires can still cause exceedances of the 24-hour PM2.5 federal standard.
PM2.5 concentrations and composition are measured throughout the SCAB with state-of-the-science regulatory and research-grade instrumentation. To study the contribution of these events to PM2.5 in SCAB in 2017 and 2018, we analyzed PM2.5 data measured by continuous Federal Equivalent Method (FEM) instruments, black carbon measurements from Aethalometers, and metal and other inorganics measurements from Cooper Xact instruments and X-ray Fluorescence (XRF) techniques. PM2.5 speciation data collected at the National Air Toxics Trends Station (NATTS) in central Los Angeles from 2012 to 2018 were also analyzed to examine the multi-year seasonal trend of organics, inorganics, metal, and elemental carbon in PM2.5 in the SCAB.
Preliminary results show that 1) PM2.5 speciation in firework emission-dominated days has distinct signatures compared to wildfire and residential wood burning emission-dominated days. 2) Metals comprise a much larger share of the total PM2.5 mass on firework days (~60%) than in wildfire and residential wood burning days (~10%). 3) On high PM2.5 days (larger than 35 µg/m3) in winter, ammonia and nitrate often dominate (>60%) the total PM2.5 mass potentially due to higher humidity typically experienced in winter, which favors the formation of ammonia nitrate in the particle phase. 4) The relative contribution of inorganic and organic mass to total PM2.5 shows a strong seasonal variation with the strongest organic contribution occurring during the winter month.