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Simplifying emissions modelling from wildland fires: laboratory-scale emission factors are independent of fine woody debris fuel load.

Elise-Andrée Guérette , Clare Paton-Walsh (Murphy) , Maximilien Desservettaz, Fabienne Reisen, Nicholas Surawski, C. P. (Mick) Meyer, Christopher Roulston , Andrew Sullivan , Christopher Weston, Liubov Volkova

Abstract

Background: Air quality modelling of smoke from wildfires requires knowledge of emission factors and how these vary. Aims: Experimental fires were used to test the variation of emission factors with fuel load to improve a smoke forecasting model. Methods: Gas and particle-phase chemical composition of smoke plumes from laboratory-scale fires was measured with different fuel loads and at different stages of fire progression. Key results: Different fine woody debris loads had no significant effect on the emissions. In contrast, different stages of the fire produced significant differences in emission factors. The lowest emission factors for most species (except carbon dioxide) were observed during the flaming fire front, which accounted for half the total emissions. Importantly, we found that emission ratios relative to carbon monoxide were consistent across different fuel loads and throughout the fire’s progression. Conclusions: By modelling the modified combustion efficiency it is possible to simultaneously model the emissions of carbon monoxide and the emissions of nearly all other pollutants throughout the progression of the fire. Implications: The emissions of carbon monoxide, fine particulate matter and other key pollutants all scale with the intensity of the fire, simplifying the task of modelling these emitted pollutants downwind of prescribed fires.

WF24117  Accepted 18 December 2024

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