Strategy for coordinating near-term PM_2.5, ozone, and CO₂ mitigation in China.

Abstract

China faces the challenge of simultaneously improving fine particulate matter (PM_2.5) and ozone (O₃) air quality while tackling climate change. However, most studies have focused on either the cocontrol of PM_2.5 and O₃ or the synergy between CO₂ reduction and PM_2.5 improvement, leaving comprehensive strategies for tackling all three underexplored. Here, we evaluate various combinations of clean-air and climate policies in China using an integrated framework that consists of a technology-based emission projection model, a goal-oriented measure selection and optimization method, a chemical transport model, and a detailed cost-benefit assessment approach. Our results show that while maintaining current clean-air policies is effective in controlling PM_2.5, their impact on O₃ remains limited. Maximizing cost-effective end-of-pipe measures targeting NO_x and volatile organic compounds can achieve cocontrol of PM_2.5 and O₃, but remain vulnerable to unfavorable meteorological conditions. Near-term climate policies alone contribute limited improvements in air quality, particularly for O₃, due to the lower synergy between CO₂ and O₃ precursor emission sources. Only a combined strategy, integrating stringent clean-air actions and ambitious climate mitigation, can achieve the "triple control" of PM_2.5, O₃, and CO₂. Under this strategy, national annual mean PM_2.5 and national O₃-8 h 90th percentile concentrations are reduced to 19.1 μg m^-3 and 126.9 μg m^-3 by 2030, respectively, yielding net benefits of over 3,000 billion RMB. Our findings can inform China's next phase of environmental policies and emission control strategies in developing regions.