Evaluating air pollution and economic impacts in Chinese megacity clusters under clean air policies

To address worsening air pollution issues, the Chinese government has incurred substantial economic costs by implementing emission reductions. This study employed the Environmental Kuznets Curve (EKC) framework to investigate the relationship between emission reductions and economic growth. The EKC exhibited similar characteristics in the Yangtze River Delta (YRD), Pearl River Delta (PRD), and Chengyu (CC), with a monotonically decreasing trend in NO_x, PM₁₀, PM_2.5, and SO₂ emissions. In contrast, completely inverted-U-shaped EKC curves were observed in the Beijing-Tianjin-Hebei (BTH) and Fenwei plain (FWP). Notably, all megacities exhibit an inverted U-shaped curve for VOC emissions in relation to GDP. The constructed emission-GDP functional model reveals distinct regional patterns, with nonlinear structures characterizing the PRD and YRD, a pronounced linear relationship dominating in the FWP, and hybrid patterns emerging in the CC and BTH. We further quantify heterogeneous economic losses from PM_2.5 and O₃ pollution, revealing distinct regional patterns tied to local development pathways. This study provides key scientific insights for exploring air pollution control strategies.