151. Impacts on Urban VOCs and PM 2.5 during a Wildfire Episode.
- Author
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Wang, Zhong-Min, Wang, Ping, Wagner, Jeff, and Kumagai, Kazukiyo
- Subjects
ENERGY dispersive X-ray spectroscopy ,WILDFIRES ,TOLUENE ,VOLATILE organic compounds ,PASSIVE sampling devices (Environmental sampling) ,WILDFIRE prevention ,THERMAL desorption ,SMOKE - Abstract
This study focuses on the impact of wildfire smoke emissions on regional, urban air quality during a wildfire event. We measured volatile organic compounds (VOCs) and fine particulate matter (PM
2.5 ) in the San Francisco Bay Area to assess air quality during a wildfire event and compared them to those in a later non-wildfire period. VOCs were collected using thermal desorption tubes and quantified using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Elevated concentrations of VOCs such as 1,3,5-trimethylbenzene (0.33 ± 0.01 µg/m3 ), benzene (1.03 ± 0.02 µg/m3 ), toluene (2.15 ± 0.04 µg/m3 ), ethylbenzene (0.60 ± 0.02 µg/m3 ), and m, p-xylene (0.77 ± 0.07 µg/m3 ) were observed in the wildfire event. Compared with that in the non-wildfire season, the toluene concentration during the wildfire period was more than three times the non-wildfire concentration. Similarly, the benzene concentration during the wildfire was almost four times higher, and that of p, m-xylene was three times higher. The higher wildfire levels were statistically significant for sec-butylbenzene, 1,2,4-trimethylbenzene, n-propylbenzene, o-xylene, styrene, 1,3,5-trimethylbenzene, benzene, toluene, ethylbenzene, and p,m-xylene (p < 0.00001). These higher VOC levels compared with those for the non-fire period may potentially pose a public health concern. Open face passive sampler (OFPS)-collected PM was analyzed using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and revealed organic carbon tar balls. The highest daily average beta-attenuation-monitored PM2.5 during the fire period was 200 µg/m3 and the highest hourly average was 270 µg/m3 . Monitoring gas phase species in addition to PM concentrations is useful during wildfire season to inform public health guidance. [ABSTRACT FROM AUTHOR]- Published
- 2024
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