Does cross-border e-commerce contribute to urban air quality improvement? Evidence from China’s pilot zones

As China's rapid urbanization and industrialization accelerate, the issue of deteriorating air quality has gained widespread attention. Cross-border e-commerce (CBEC), as a representative of digital trade, provides a new solution for improving environmental governance performance. Based on panel data from 284 Chinese cities from 2009 to 2022, this paper utilizes the establishment of CBEC pilot zones as a quasi-natural experiment and employs a multi-period Difference-in-Differences method to assess the effect of CBEC on urban sulfur dioxide (SO2) emissions. The results indicate that CBEC significantly improves urban air quality. Heterogeneity analysis shows that this effect is particularly pronounced in eastern cities, especially those with higher levels of digital infrastructure and weaker environmental regulations. Mechanism tests further reveal that CBEC effectively enhances urban air quality by the pathways of green technology innovation, productive service industry agglomeration, and resource allocation optimizing. Therefore, it is essential to accelerate CBEC reforms, promote the construction of CBEC pilot zones, and strengthen policy implementation to fully leverage its potential in improving urban air quality.