The Influence of Prescribed Fire on Fine Particulate Matter Pollution in the Southeastern United States

Prescribed fire is the largest source of fine particulate matter emissions in the Southeastern United States, yet its air quality impacts remain highly uncertain. Here, we assess the influence of prescribed fire on observed pollutant concentrations in the region using a unique fire data set compiled from multiyear digital burn permit records. There is a significant association between prescribed fire activity and concentrations recorded at Southeastern monitoring sites, with permitted burning explaining as much as 50% variability in daily PM2.5 concentrations. This relationship varies spatially and temporally across the region and as a function of burn type. At most locations, the association between PM2.5 concentration and permitted burning is stronger than that with satellite-derived burn area or meteorological drivers of air quality. These results highlight the value of bottom-up data in evaluating the contribution of prescribed fire to regional air pollution and reveal a need to develop more complete burn records. Plain Language Summary Prescribed fires, planned and intentionally ignited wildland fires, are frequently used in the Southeastern United States for different land management purposes, such as reducing the risk of catastrophic wildfires and restoring ecosystems. They are also the largest source of fine particle emissions into the atmosphere in the Southeast. However, the extent to which prescribed fires contribute to air pollution in the region remains unclear. In this study, data gathered from state burn permit records and regulatory air quality monitors are used to show that prescribe fire has an important influence on air pollution at multiple Southeastern locations. Additionally, our analysis suggests that burning permits can be more informative than satellite-derived fire data when evaluating the impacts of prescribed fire on regional air quality. These results reveal a need to improve available records of prescribed fire activity in order to better understand its full effect on air pollution in the Southeast.