How Could Prescribed Fire Have Altered the Health Impacts of the 2016 Appalachian Wildfires?

In the fall of 2016 numerous wildfires burned across more than 100,000 acres of forest land in the southern Appalachians. These fires spread smoke across much of the southeastern United States and were linked to hundreds of hospital admissions for respitory problems. The Rough Ridge fire in north Georgia was one of the many wildfires impacting the region during this period of persistent drought conditions. Despite primarily burning with low severity, metro Atlanta about 150 km to the south, was hit by heavy smoke during the period from November 10-15. This study investigates whether more extensive use of prescribed fire could have mitigated the severe air quality impacts of this fire. Fuel sampling was conducted at a pair of burned and unburned sites that had not experienced fire for decades, and a pair of sites where one had been treated with prescribed fire prior to the wildfire. Fire emissions were calculated using the Bluesky Playground for the actual fuel condition for the wildfire as well as three experimental fuel scenarios: typical FCCS fuel loading, high fuel moisture, and fuels with prescribed fire treatment. A major feature of the forest fuels in the fire site was a very deep duff layer accumulated over decades due to the lack of historical fires. Typically, the duff layer is wet and often burns only slightly during the smoldering stage. However on the Rough Ridge fire, drought conditions allowed for consumption of the majority of the duff layer. This contributed substantially to the large PM2.5 emissions and resulting high concentrations in metro Atlanta. In contrast, no or only weak air pollution in metro Atlanta was simulated for each of the three experimental fuel scenarios. These results suggest that prescribed fire would be a valuable and efficient management tool to reduce the duff layer and therefore reduce the potential air quality impacts of future wildfires in this region.