Can the New Subway Line Openings Mitigate PM10 Concentration? Evidence from Chinese Cities Based on the PSM-DID Method

Abstract

The large-scale construction of subway systems, which is viewed as one of the potential measures to mitigate traffic congestion and its resulting air pollution and health impact, is taking place in major cities throughout China. However, the literature on the impact of the new subway line openings on particulate matter with a diameter less than 10 µm (PM10) at the city level is scarce. Employing the Propensity Score Matching–Difference-in-differences method, this paper examines the effect of the new subway line openings on air quality in terms of PM10 in China, using the daily PM10 concentration data from January 2014 to December 2017. Our finding shows that the short-term treatment effect on PM10 is more controversial. Furthermore, for different time windows, the result confirms an increase in PM10 pollution during the short term, while the subway line openings improve air quality in the longer term. In addition, we find that the treatment effect results in high PM10 pollution for cities with 1–2 million people, while it improves air quality for cities with over 2 million people. Moreover, for cities with varying levels of GDP, there is evidence of a reduction in PM10 after the subway line openings. Mechanism analysis supports the conclusion that the PM10 reduction originated from substituting the subway for driving.

Patients’ and Care Professionals’ Evaluation of the Effect of a Hospital Group on Integrated Care in Chinese Urban Health Systems: A Propensity Score Matching and Difference-in-differences Regression Approach

“…Third, the PSM-DID regression approach addressed both the sample selectivity bias and individual heterogeneity and effectively estimated the net effect of the hospital group. 41 …”

Block Chain Policy’s Impact on Firms’ Performance Based on PSM-DID

“…The difference-in-difference method is becoming more and more popular since it is a potent instrument in the policy effect evaluation method [8][9]. In summary, there are various reasons: (1) It can substantially reduce the hassle of endogenous issues: general policy.…”

Does Environmental Policy Help Green Industry? Evidence from China’s Promotion of Municipal Solid Waste Sorting

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