Impacts on Urban PM2.5 and VOCs during a Wildfire Episode
ZHONG-MIN WANG, Ping Wang, Jeff Wagner, Kazukiyo Kumagai,
California Department of Public Health Abstract Number: 12
Working Group: Aerosol Exposure
AbstractThis study focuses on the impact of wildfire smoke emissions on regional air quality. Specifically, we measured fine particulate matter (PM2.5) and volatile organic compounds (VOCs) before and after the Butte County Camp Fire (California) of November 2018. Ambient air in the San Francisco Bay Area was monitored and sampled using a beta attenuation monitor (BAM), open face passive samplers (OFPS), and thermal desorption tubes to assess PM and VOCs during the wildfire episode and a later non-wildfire period. OFPS-collected PM was analyzed using Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) for detailed morphology and elemental composition. VOCs were analyzed and quantified using Thermal Desorption-Gas Chromatography/Mass Spectrometry (TD-GC/MS). The highest daily average BAM PM2.5 during the fire period was 200 mg/m3 and the highest hourly average was 270 mg/m3. The daily average of BAM PM2.5 in the Bay Area during the wildfire episode was 102 mg/m3. Electron microscopy analysis of the OFPS samples revealed organic carbon tar balls. Elevated concentrations of VOCs such as 1,3,5-Trimethylbenzene (0.33±0.01 mg/m3), Benzene (1.03±0.02 mg/m3), Toluene (2.15±0.04 mg/m3), Ethylbenzene (0.60±0.02 mg/m3), and m, p-Xylene (0.77±0.07 mg/m3) were observed in the wildfire episode. These VOC levels were several times higher than the non-fire period and may potentially pose a public health concern. Monitoring gas phase species in addition to PM concentrations is useful during wildfire season to protect public health.