Contributions of local household fuel burning and regional transport to ambient PM2.5 in the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau (QTP), despite its much low PM2.5 levels, has limited access to clean household energies. However, residential emission contributions to ambient PM2.5 are insufficiently quantified owing to scarce regionally representative household energy data and complex influences of local emissions and regional transport. In this study, we updated the residential emission inventory from 1960 to 2019 for the QTP based on survey-based household energy consumption data, and adopted normalized marginal method to evaluate ambient PM2.5 source contributions with GEOS-Chem simulations. Residential emissions increased from 1960 to around 1990 and then gradually declined, broadly consistent with partial clean energy transition. Emissions were dominated by the inefficient combustion of animal dung, except for SO2, which was more strongly influenced by coal combustion. Residential emissions accounted for >80% of total primary PM2.5 emissions in QTP; however, all local sources contributed 17% of ambient PM2.5 in Tibet and 46% in Qinghai. Transport from South Asia accounted for 65% of annual ambient PM2.5 in Tibet, while local emissions played a larger role in Qinghai. Within the local-source component, residential emissions accounted for 66% in Tibet and 44% in Qinghai. These results provide an improved basis for understanding PM2.5 pollution over the QTP and for developing regionally differentiated mitigation strategies.