Is the High-Speed Rail Opening Environmentally Friendly? Taking the Difference-in-Differences Test in Jiangsu, China

Table 7

Comparisons of high-speed rail opening impact.

Study	Research area	Research period	Pollutants	Methodology	Results
Previous study	China	2008–2015	Carbon dioxide	LCA	Reduce carbon emissions by 26.1 million tons (Wang et al. [36])
	270 cities, China	2003–2016	Industrial emissions per capita	DID	Decrease by 23.35% (Zhu et al. [29])
	285 cities, China	2003–2016	PM2.5	DID	Decrease by 1.81% (Zhang and Feng [37])
	271 cities, China	2007–2015	Sulfur dioxide, industrial waste water, and industrial smoke	Bidirectional fixed effects model	Decrease by 2.505, 1.215, and 2.505 (Zhang et al. [38])
	Yangtze River Economic Belt, China	2007–2017	Comprehensive index of environmental pollution	PSM-DID	Decrease by 8.6% (Zhang and Zhang [16])
This study	Jiangsu province, China	2000–2017	Reach the second-order (good) days	DID	Increase by 21.5%