Synergistic pollution and carbon reductions from the China National Sustainable Communities Pilot Policy

The China National Sustainable Communities (CNSC) pilot policy has propelled sustainable development efforts nationwide, but whether and how it achieves synergies between pollution mitigation and carbon reduction remains underexplored. Using panel data from 225 Chinese cities from 2003 to 2017, this study evaluates the impact of CNSC policy on these synergies by employing a time-varying difference-in-differences (DID) method. The findings reveal that the CNSC policy significantly fosters these synergies alongside economic growth, resulting in a 33 % increase in economic output, a 2.8 % reduction in PM_2.5 levels, and a 1.5 % decrease in CO₂ emissions. Technological innovation and economies of scale are identified as key mechanisms through which the CNSC policy operates. Specifically, technological innovation drives carbon reduction in prefecture-level, mature, non-resource-based, and southern regions, while focusing on air pollution mitigation in resource-based cities. The CNSC achieves synergistic reductions across nearly all categories through economies of scale. Additionally, most pilot zones demonstrate effective synergistic reductions, with a more pronounced impact on PM_2.5 reduction compared to CO₂ reduction.