Understanding the contributions of different types of biomass combustion to ambient PM2.5 and ozone in the United States using CMAQv5.3.3

JIAOYAN HUANG, Shih-Ying Chang, ShinMing Huang, Frederick Lurmann, Sonoma Technology Inc.

     Abstract Number: 589
     Working Group: Biomass Combustion: Outdoor/Indoor Transport and Indoor Air Quality

Abstract
In this study, we investigated the contributions of different types of biomass combustion emissions on human exposure to fine particulate matter (PM_2.5) and ozone (O₃) concentration in California in 2018, one of the top years for fire activity. Using the emissions inventories developed in this study and by the U.S. Environmental Protection Agency (EPA), we applied the Community Multiscale Air Quality (CAMQ) model and a brute force (BF) method to investigate the contribution of PM_2.5 and O₃ emissions from wildfires (WF), prescribed fires (Rx), agricultural fires (AG), and residential wood combustion (RWC) in the U.S. and, more specifically, California.

Non-biomass emissions, AG fires emissions, meteorological data, and boundary/initial conditions were developed and provided by the EPA from their previous studies on WF contributions to air pollution. CMAQ was run without implementing potential secondary organic aerosol from combustion emissions (PcSOA) for these biomass emission sectors as suggested by CMAQ release notes. The performance of the resulting CMAQ simulation was reasonable, and the normalized mean bias for total PM_2.5 and O₃ emissions ranges from 30-35% and 0-15%, respectively.
WF is the most important emission source of PM_2.5 from July-September in California, with monthly average contributions ranging from 50-75%. WF is also the most important biomass emission sector on a national scale, at 25-50%. The second largest contributor of PM_2.5 is Rx emissions (monthly contribution from >5-25%); however, the variations of Rx PM_2.5 contributions from October-April were higher nationally than in California. RWC can contribute up to 15% of monthly averaged PM_2.5 emissions in California and nationally. Detailed seasonal and spatial variations of biomass burning contributions and chemical composition of PM_2.5 will be discussed and presented. The results of the study will be used for understanding the relationship between (1) biomass burning smoke exposures during pregnancy, and (2) preterm births in California.