Exploring the Variability in Emissions for Broadcast and Pile Prescribed Burns Using Low-Cost Sensors

Prescribed fire is an effective tool for reducing wildfire risk but emits pollutants such as carbon monoxide (CO) and fine particulate matter (PM2.5) that negatively impact both indoor and outdoor air quality. While emissions from prescribed fires have been widely characterized, there remains limited understanding of how emissions vary across combustion conditions, fuel types, and regions. More specifically, there has been little work that has looked at both emissions of CO and PM2.5 as well as other compounds such as elemental carbon (EC), organic carbon (OC), and speciated organic compounds. This work quantifies the variability of emission factors (EFs) for CO, PM2.5, EC, OC, and speciated organic compounds across 19 prescribed fires in Colorado and southeastern Georgia using low-cost sensors. This allowed us to have highly temporally resolved EF datasets across multiple monitors and multiple burns. Results show that CO EFs are strongly driven by combustion phases, with higher emissions associated with lower modified combustion efficiency, or smoldering combustion (+3260%). However, PM2.5 EFs exhibit weaker and more variable relationships with combustion phase and are more strongly influenced by fuel type (+108% for Colorado-based fuels) and burn characteristics (+8.3%). Broadcast burns generally exhibited higher CO and PM2.5 EFs than pile burns, while daytime burning conditions were associated with lower emissions for both CO and PM2.5. The results provide improved emission factor estimates across multiple conditions and can inform both prescribed fire management practices and the development of more representative emissions inventories.