Abstract Description: Wildfire emissions include significant quantities of gaseous pollutants. During wildfire emissions transport, ozone is produced via reaction of oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. These emissions typically enhance ozone production downwind. However, the downwind effect of wildfire emissions need to be better characterized. This study collected wildfire-specific VOC samples to trace wildfire influence on ozone production in an urban airshed. We deployed low-cost, automated active-sampling thermal desorption field samplers and Summa Canisters (canister) that collected VOC samples. In addition to speciated PM2.5 and levoglucosan measurements, twelve wildfire-specific VOCs were selected to trace wildfire emissions, such as acetonitrile and furans as well as benzene and toluene for comparison with existing measurements. Sampling was conducted during ozone/wildfire season of 2023 and 2024. Laboratory analysis methods included total organic (TO) TO-15 and TO-17 (2023 only). Samples were collected at monitoring sites in Clark County, Nevada, including national core monitoring stations (NCore) and photochemical assessment monitoring stations (PAMS) site to provide comparisons with established datasets and co-located with canister samples. Wildfire-specific and background samples were collected, and statistically significant results were observed between wildfire-specific samples and non-wildfire samples. For wildfire events, enhancements in wildfire-specific VOCs such as acetonitrile and benzene were observed. Expanding this methodology will allow agencies to identify when wildfire emissions are affecting their area, quantify the impact on ozone production, develop more effective exceptional event demonstration submittals, and meet Clean Air Act (CAA) and national ambient air quality standards (NAAQS) attainment objectives.
