Does high-speed rail construction reduce air pollution? Evidence from prefecture-level cities in China

Based on data from 282 cities in China, this study assesses the impact of high-speed rail (HSR) construction on air pollution with a difference-in-difference (DID) method and a quasi-natural experiment of HSR construction. The results indicate HSR construction reduces air pollution, specifically, PM2.5 concentrations in HSR cities decreased by 2.91 %. Moreover, heterogeneity exists in the influence of HSR on air pollution of different types of cities. Considering cities of different administration levels, HSR construction significantly reduces air pollution in peripheral cities, while the pollution reduction in core cities is not obvious. Considering cities with different population sizes, the HSR construction suppresses air pollution in small cities and big cities, while this suppressive effect in small cities is more obvious. The mechanism analysis confirms HSR construction reduces PM2.5 by three ways: substituting civil aviation, adjusting industrial structure, and enhancing innovation foundation. Meanwhile, a spatial spillover effect exists in HSR's effect on air pollution: HSR construction reduces air pollution in local cities, while also promoting air quality in neighboring cities due to the spatial correlation between cities.