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 PM 2.5 emission reductions and persistent fluctuations in ozone (O 3 ), 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 PM 2.5 and O 3 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 PM 2.5 decreased by 2.92 µg/m 3 , while O 3 slightly decreased by 0.32 µg/m 3 , although it rebounded by 1.25 µg/m 3 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 PM 2.5 and O 3 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 PM 2.5 and O 3 exposure risks by 13% and 10%, respectively. Moreover, the concentration index of O 3 -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 PM 2.5 –O 3 coordinated control policies, providing scientific support for optimizing future synergistic and equitable air quality strategies.