The impact of high-speed rail on air quality in counties: Econometric study with data from southern Beijing-Tianjin-Hebei, China

High-speed rail (HSR) is considered a safe, fast, comfortable and ecological mode of transportation, which has profoundly changed the way passengers travel. However, how green it is and how it affects county air quality remains to be investigated. Based on panel data of 51 counties in southern Beijing-Tianjin-Hebei (Ding-Jin-Ji) from 2014 to 2018, Fixed Effect Model (FEM) and Propensity-Score-Matching and Difference-in-Difference (PSM-DID) methods are used to study the impact of HSR on air quality in counties. FEM is used as the preliminary regression and PSM-DID model is used to avoid the endogenous problem and selection bias. Research shows that HSR has direct and indirect effects on air quality in counties. HSR directly affects it by changing the way of long-distance travel. Furthermore, HSR indirectly affects it by promoting the regional economy, which affects air quality through scale effects, innovation effects and structural effects caused by regional economy development. The results show that the operation of the HSR reduces the air quality index (AQI) by 11.2% and the concentrations of the three major pollutants index, including PM2.5 by 10.1%, PM10 by 14.8% and O-3 by 11%. We also find that HSR brings at least 4% more environmental benefits on the side closer to Beijing and Tianjin in southern Jing-Jin-Ji than the farther side. Among the two sides, the closer side has more government concern and economic activities. In addition, we conducted further robustness tests and concluded that HSR improves air quality in counties. This paper provides some policy implications for improving county environmental quality and planning of HSR stations. (C) 2020 Elsevier Ltd. All rights reserved.