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Impacts of Residential Wood Burning Curtailment Program on Wintertime PM Pollution in the San Joaquin Valley of California
JUSTIN TROUSDELL, Caroline Parworth, Ryan Farley, Deepchandra Srivastava, Qi Zhang, University of California, Davis
Abstract Number: 497
Working Group: Source Apportionment
Abstract
Over the past three decades extensive efforts have been made to decrease particulate matter (PM) related to residential wood burning (RWB) in the San Joaquin Valley (SJV) of California. This effort goes hand in hand with decreasing violations of the National Ambient Air Quality Standards (NAAQS) for PM and reducing the health risks of wood smoke. The control district and the counties place restrictions on RWB based on forecasted meteorology and PM emissions under rule 4901. Here we investigate the compliance rate of curtailment restrictions and the effects of rule 4901 on PM2.5 pollution in SJV. A key tracer species for biomass burning in this region is biomass burning organic aerosol (BBOA) resolved via source apportionment of organic aerosol spectra acquired with aerosol mass spectrometers. To see if RWB species mass concentrations were reduced in accordance with curtailment restrictions, hourly percent changes in BBOA concentrations were calculated by comparing average diurnal concentrations of RWB species during curtailment to those during burning-allowed periods for the 2018-2019 and 2012-2013 winter seasons. The comparison was then performed after normalizing the diurnal concentrations with background corrected CO or NOx, which are expected to have relatively low contributions from RWB, to correct for well-known systematic meteorological differences. The percent differences between 6 pm to midnight, when RWB emissions primarily occur, are small for the 2018-2019 winter. This suggests that compliance with restrictions was low for this winter. However, significant reduction of RWB emissions was observed in the 2012-2013 winter season when BBOA concentration was 2 times higher than the 2018-2019 season. Although compliance is low decreasing trends in PM2.5 and BBOA suggest that the total number of people burning is less than in previous years.