The Trade-offs between Wildfires and Prescribed Fires: A Case Study for 2016 Gatlinburg Wildfires

Prescribed burning is an effective land management tool that provides a range of benefits, including ecosystem restoration and wildfire risk reduction. However, prescribed fires, just like wildfires, introduce smoke that degrades air quality. Furthermore, while prescribed fires help manage wildfire risk, they do not eliminate the possibility of wildfires. It is therefore important to also evaluate fire and smoke impacts from wildfires that may occur after a prescribed burn. In this study, we developed a framework for understanding the air quality and health related trade-offs between wildfires and prescribed fires by simulating a set of counterfactual scenarios including wildfires, prescribed fires, and postprescribed burn wildfires. We applied this framework to the case of the Gatlinburg wildfire and found that emissions from prescribed burns and subsequent wildfire were slightly lower than those from the wildfire itself. This reduction resulted in lower daily average concentrations and exposures of PM_2.5, O₃, and NO₂. Even considering the possibility of a postprescribed burn wildfire, prescribed fires reduced population-weighted daily average PM_2.5, daily maximum 8-h average O₃, and 1-h maximum NO₂ concentrations. In Sevier County, Tennessee where the wildfire occurred, these reductions reached 5.28 μg/m³, 0.18 ppb, and 1.68 ppb, respectively. The prescribed fires also reduced the person-days smoke exposures from the wildfire. Our results suggest that although prescribed fires cannot eliminate the air quality impacts of wildfires, they can greatly reduce smoke exposure in downwind areas distant from the burn sites.

The work proposes a modeling framework which considers emissions from prescribed fires, wildfires, and postprescribed burn wildfires for understanding the air quality trade-offs between wildfires and prescribed fires.