With the fast-growing consumption of automobiles in China, vehicle fumes appear to be one of the major contributors to PM_2.5 (fine particles with a diameter of 2.5 μm or less) emissions. As a type of green transportation, Chinese urban subway transit has developed rapidly in recent years. This paper estimates the effect of urban subway openings on PM_2.5 concentrations in Chinese cities. Using daily air quality data for 29 Chinese cities from 2013 to 2018, and using regression discontinuity design, we find that new subway openings reduce PM_2.5 concentrations by an average of 18 μg/m³. The potential mechanism for this emission reduction is due to the offset in on-road transportation, and the use of cleaner energy. Also, central heating in winter, population scale, and city tier play crucial roles in the emission-reducing effect of subway openings. A series of robustness tests are conducted to support the fundamental empirical results. Targeted policy implications, such as optimizing the planning of urban subway construction and road network, fostering awareness of green travel, and promoting the innovation of emission-reducing technologies, are suggested for sustainable development in Chinese cities.

The property income growth of urban and rural residents is an important part of the continuous increase in the disposable income of these residents, which is also inseparable from the deepening development of the financial market. After sorting out the various sources of income that affect residents’ property in the existing research and controlling regional fixed effects, based on data from 31 provinces in China, this article considers important financial factors and the process of urbanization as explanatory variables to perform panel regression on the property income of provincial residents under fixed effects and random effects. In the context of large differences in the investment environment between urban and rural areas, we further examine the effects of financial factors on the property income of urban and rural residents. Only by expanding the investment opportunities and enhancing the investment ability of the residents, can the property income of the residents, especially the rural residents, be guaranteed to grow steadily and sustainably.