Synergistic effects of air pollution control policies: Evidence from China

To control severe air pollution, multiple policies have been adopted in China. However, the combined effect of these policies on reducing air pollution remains uncertain. By systematically evaluating the complementary and substitution effects of policy combinations across different regions, this study aims to identify the optimal combinations of multiple air pollution control policies and to explore the mechanisms of policy synergy, maximizing improvements in air quality. Using a panel data from 334 Chinese cities collected between 2015 and 2019, we assess the effectiveness of fifteen air quality policies across eight categories. Our findings indicate that combining diverse policy measures yields more significant improvements in air quality due to the complementary effects among policies. Conversely, combinations of similar policy types exhibit weaker effects because of substitution effects. A comprehensive policy package, integrating stringent industrial emissions standards, residential energy transition strategies, market-based trading mechanisms, and multi-level supervision, may represent the most effective approach for air quality enhancement.