Impacts of Emission Control Policies on Air Quality and Environmental Justice Over the Pearl River Delta for 2021–2025

During the 14th Five-Year Plan (2021–2025), the Pearl River Delta (PRD) faces the dual challenges of a slowdown in PM2.5 emission reductions and persistent fluctuations in ozone (O3), raising concerns about the effectiveness and equity of current control strategies. To address this, we developed an integrated assessment framework that combines 2025 Business-as-Usual (BAU) and Policy Scenarios (PS) with the Response Surface Model (RSM) to systematically quantify the non-linear responses of PM2.5 and O3 to specific interventions, and translated these changes into health benefits and environmental justice outcomes. Our results indicated that compared with BAU, the PS reduced precursor emissions by 14–28%. Therefore, the regional average PM2.5 decreased by 2.92 µg/m3, while O3 slightly decreased by 0.32 µg/m3, although it rebounded by 1.25 µg/m3 in the central VOC-limited area. These changes were driven primarily by ultra-low-emission retrofits in non-petrochemical industries and the promotion of low-VOC industrial solvents. The mitigation of PM2.5 and O3 pollution avoided an estimated 6,565 (95% CI 5447–7586) premature deaths and generated economic benefits of $4.53 billion. Regarding environmental justice, the policies generally reduced health disparities, lowering the regional average Gini coefficients for PM2.5 and O3 exposure risks by 13% and 10%, respectively. Moreover, the concentration index of O3-related mortality reversed from -0.028 to 0.022, alleviating the health burden in less affluent regions. The proposed framework serves as a transferable tool for measure-level evaluation of PM2.5–O3 coordinated control policies, providing scientific support for optimizing future synergistic and equitable air quality strategies.