Source contributions to ozone-related mortality burdens: Attribution-based diagnostics for emission control planning in China

Ozone (O₃) pollution imposes health burdens across China, yet the differential contributions of interregional transport and sectoral emissions remain insufficiently quantified to support diagnostic assessment and regional planning. To address this gap, we developed a coupled emission-concentration-health modeling framework that integrated the Integrated Source Apportionment Method (ISAM) within the Community Multiscale Air Quality (CMAQ) model with a health impact assessment module. This framework quantified the contributions of 155 emission sources (five sectors across 31 provinces) to O₃-related mortality across China in 2019. Our analysis indicates that long-term O₃ exposure caused 143,420 (95% CI: 72,267–212,609) premature deaths nationwide. Interprovincial transport accounts for 54.0% of the total mortality burden, reflecting spatial spillover effects. The industry and transport sectors collectively contribute approximately 60% of the national mortality burden. Notably, the top 31 emission sources account for over half of the total burden, identifying them as high-contribution sources. By comparing the relative contributions of emission sources to PM_2.5- and O₃-related mortality, we classified these sources into three pollution contribution categories: PM_2.5-higher-contribution sources, O₃-higher-contribution sources, and comparable-contribution sources. These findings offer region-specific attribution insights to support synergistic control of PM_2.5 and O₃. Collectively, this study establishes a diagnostic framework to screen sources that warrant regulatory attention and provides an attribution-based reference for coordinated air quality management.