China’s cross-border e-commerce comprehensive pilot zones: emission reduction and spatial spillover effects on air quality

Cross-border e-commerce (CBEC) is currently the fastest-growing and most promising new trade format, acting as a pivotal engine for transforming and upgrading China’s foreign trade. While the rapid expansion of CBEC has profoundly impacted the economy, its potential environmental externalities remain underexplored. Based on panel data from 276 prefecture-level cities in China spanning 2010 to 2022, this study treats the phased implementation of the Cross-border e-commerce Comprehensive Pilot Zone (CPZ) policy as a quasi-natural experiment. By employing multi-period difference-in-differences (DID) and spatial econometric models, we evaluate the impact of the CPZ policy on PM2.5 concentrations in both pilot cities and their neighboring areas. The findings reveal that: (1) The CPZ policy significantly reduces PM2.5 concentrations in pilot cities, a conclusion that remains consistent across multiple robustness tests, including alternative indicators, instrumental variables, PSM-DID, and double machine learning. (2) The emission reduction effect is more pronounced in resource-based cities and non-environmental priority cities. (3) The CPZ generates emission reduction spillover effects on surrounding cities within a 0–300 km radius, primarily transmitted through channels involving spatially diffusive green technological innovation, digital technological innovation, and energy consumption intensity. Based on these findings, the following policy implications are derived: (1) Continuously promote the high-quality development of CPZs and strengthen the green development orientation. (2) Formulate region-specific and differentiated policies based on local conditions. (3) Enhance regional coordination and technology spillover mechanisms. (4) Build a dual-drive system integrating green technology and digital technology.