The air quality trade-offs of wildfire and prescribed burning

Abstract:

Wildland fires, including both wildfires and prescribed burns, are the largest source of fine particulate matter (PM_2.5) emissions in the U.S. While wildfires are unplanned, prescribed burns are a controlled application of fire to accomplish land management objectives, such as wildfire hazard mitigation and ecological restoration. However, the degree to which prescribed fire may also mitigate the severe air quality impacts of wildfires is not well understood. Here, we examine the trade-offs between the air quality impacts of prescribed burning and the avoided air pollution from wildfire using comprehensive regional-scale chemical transport modeling. We simulate the impact of two 2016 wildfires in western North Carolina, the Party Rock and Chestnut Knob fires. We use wildfire emissions generated with the SmartFire-BlueSky Pipeline emissions modeling framework. We also create prescribed fire emission profiles based on existing fuel beds at the Chimney Rock and South Mountain State Parks, where the wildfires occurred, and estimate their consumption of different vegetative fuels. Based on the fuel loads subsequent to prescribed fire, we simulate the emissions and smoke impacts of hypothetical wildfires that would have occurred at the State Parks if prescribed fire treatment had been previously applied to the area burned. We find that the avoided air quality impacts of wildfires are higher than the added impacts of all prescribed fires needed to treat the wildfire area. A smaller population is affected by increased PM_2.5 concentrations from prescribed fires compared to the that benefiting from the avoided exposure to wildfire air pollution. The approach and findings presented can support decision-making, and the use of efficient land management approaches.