Revealing the Important Contribution of Fresh and Aged Ozone-Depleting Substances from Residential Solid Fuel Combustion to Stratospheric Ozone Depletion Potential

Ozone-depleting substances (ODSs) emitted from residential solid fuel combustion, although not regulated under the Montreal Protocol (MP), contribute substantially to stratospheric ozone depletion and therefore warrant systematic assessment. This study conducted combustion experiments using traditional stoves, examining ODS emissions from three typical biomass and two types of coal and their contributions to ozone depletion. The emission factors of ODSs (∑EFODS) were substantially higher for biomass burning (1049.4–2922.8 mg/kg) than for coal combustion (45.6–54.8 mg/kg), leading to much greater ozone depletion potential (ODP) weighted emissions from biomass fuels (78.9–766.1 mg/kg CFC-11-equivalent) compared with coal (10.5–19 mg/kg CFC-11-eq). Methyl halides dominated ODS emissions (79.7–92.8%) from biomass burning, while chlorinated methane (52.4–57.6%) and CFCs (31.9–33.5%) were major ODS emissions from coal combustion. ∑EFODS from biomass and coal combustion decreased by about 50% and 20%, respectively, after 6-equivalent days aging due to substantial degradation of chlorinated methane and CH3Br. Additionally, CFCs generation was observed during the aging process. The annual ODS and CFC-11-eq emissions from residential solid fuel combustion in the Guanzhong Plain in 2022 were estimated at 9,708 and 1,289 tons. Our results further indicate that atmospheric aging needs to be considered when assessing the contribution of solid fuel combustion to ozone depletion.