Emissions of PCDD/Fs in PM_2.5 from biomass and coal burning in China: Highlighting the need for emission control

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from biomass and domestic coal burning have attracted increasing scientific attention. However, the emission characteristics and inventories of these sources remain poorly constrained, representing a key knowledge gap in our understanding of atmospheric PCDD/F sources. Based on plume downwind sampling in field and dilution tunnel sampling in laboratory, we determined the I-TEQ-based emission factors of PCDD/Fs in PM_2.5 for open biomass, domestic biomass, and domestic coal to be 0.96 ± 0.65, 0.62 ± 0.48, and 0.52 ± 0.22 ng I-TEQ/kg, respectively. A new emission inventory of PCDD/Fs in PM_2.5 from biomass and domestic coal burning in China was subsequently established, revealing that the total previously overlooked emission of these sources amounted to 229.41 g I-TEQ in 2022. Compared to other source categories, biomass and coal burning are significant contributors to PCDD/Fs in PM_2.5, particularly in Northeast China, where emission is 6.8 times that from industrial coal burning and 0.7 times that from municipal solid waste burning. Furthermore, the health risks associated with inhalation exposure to PCDD/Fs emissions in PM_2.5 from open biomass, domestic biomass, and domestic coal burning were (1.68 ± 1.55) ×10^-5, (8.58 ± 6.71) × 10^-5, and (2.64 ± 1.45) ×10^-5, respectively, which are 0.6, 3.0, and 0.9 times those for factory workers, indicating that the health risks of residents exposed to biomass and coal burning warrant considerable attention. This study provides direct evidence highlighting the need for PCDD/Fs emission control from biomass and coal burning. These findings are also crucial for updating national emission inventories and guiding source-specific control strategies.