How does high-speed rail construction affect air pollutant emissions? Evidence from the Yangtze River Delta Urban Agglomeration in China

Taking the construction of high-speed rail as a “quasi-natural experiment”, the panel data of 26 cities in the Yangtze River Delta from 2004 to 2018 were selected as samples, and a difference-in-differences model was constructed to study the impact of high-speed rail construction on air pollutant emissions. Furthermore, the meditating effect model and difference-in-differences model were built to explore the paths of high-speed railway construction affecting air pollutant emissions. According to the study, the construction of high-speed rail reduces industrial sulfur dioxide emissions and increases the emission of industrial smoke and dust, which are more obvious in areas with good economic conditions. The role of high-speed rail in reducing emissions is realized through the structure effect, technological effect and substitution effect. However, the construction/renovation process of high-speed rail lines or stations does increase the industrial smoke and dust emissions. In this study, the bidirectional effects of high-speed rail construction on different air pollutant emissions were identified, including the high-speed rail construction process into the research. Multiple paths of action were proposed, bridging the gap of existing studies. The study reveals that controlling the air pollution emissions throughout the full life cycle of the high-speed rail, from the construction process to its operation, was essential.