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Long-Term Trends of PM2.5 and Its Carbon Content in the South Coast Air Basin: A Focus on the impact of Wildfires
FARAZ ENAYATI AHANGAR, Sina Hasheminassab, Payam Pakbin, Scott A. Epstein, Andrea Polidori, Jason Low, South Coast Air Quality Management District
Abstract Number: 433
Working Group: Carbonaceous Aerosol
Abstract
Implementation of stringent regulations on stationary and mobile sources at the local, state, and federal levels over the past two decades resulted in a substantial reduction of ambient concentrations of and its carbonaceous content including elemental carbon (EC) and organic carbon (OC) in the South Coast Air Basin (SCAB). With these reductions in concentration levels, the contribution from wildfire, as a major source of and EC which cannot be controlled through regulations, is gaining more significance. Dry conditions in recent decades have also contributed to increased frequency and intensity of wildfire events throughout the SCAB.
Many studies have addressed the short-term effects of wildfires on concentration levels during fire episodes; however, few have analyzed and quantified the long-term influence of wildfires on air quality in the SCAB. These studies have suggested that the long-term levels of EC concentration might be impacted by the wildfire contributions. In this work, we have analyzed the long-term trends of , EC, and OC at four monitoring sites in the SCAB from 2004 to 2018. Using a back-trajectory model combined with a fire emission inventory we determined the days that were affected by wildfires and compared the air quality levels on these days to the rest of the study period. The results suggest that while wildfires caused elevations in concentration of , EC, and OC in SCAB in relatively short temporal scales around fire episodes, their impacts on long-term trends were not statistically significant as some of the previous studies have suggested.