Achieving synergistic governance of air pollution treatment and greenhouse gas emission reduction is the way for the Chinese government to achieve green transformational development. Against this background, this paper takes the implementation of the carbon emissions trading system (ETS) as the breakthrough point, using the time-varying difference-in-differences (DID) model to explore the synergistic emission reduction effect of ETS on air pollution and carbon emissions and its mechanism. The results indicate that the implementation of ETS not only significantly reduces CO₂ emissions but also synergistically achieves the reduction of air pollutants, and the synergistic emission reduction effect is mainly achieved through the synergistic reduction of SO₂. Moreover, the emission reduction effect of ETS has economic and regional heterogeneity. On the one hand, the ETS has a more prominent carbon reduction effect in less developed provinces and cities and has a significant synergistic emission reduction effect on SO₂ and PM_2.5; on the other hand, the carbon emission reduction effect of ETS is more potent in Beijing, Hubei, and Shanghai, followed by Tianjin and Chongqing, and the weakest in Guangdong. In addition, through the analysis of the mediating effect, this paper finds that reducing energy consumption, optimizing the energy structure, and improving energy efficiency are effective ways for ETS to achieve synergistic emission reduction. This study provides valuable policy enlightenment for promoting the synergistic governance of pollution and carbon reduction.

Fiscal decentralization (FD), as an institutional arrangement for the fiscal division between central and local governments, gives local governments the enthusiasm and autonomy to provide public products and services. With the dominance of environmental governance, how local governments can avoid intergovernmental “race to the bottom” issues through green technology innovation (GTI) is a matter of regional green development and continuous improvement of atmospheric environmental quality. Based on a sample of 30 provinces in China from 2003 to 2018, this paper uses the spatial Durbin model (SDM) to examine the relationship between FD, GTI, and regional air pollution and explores their spatial spillover effect and regional heterogeneity from the perspective of intergovernmental competition. The results indicate that the FD and GTI in various provinces had significant and regionally differentiated inhibitory effects on local air pollution. In Western China, due to the regional competition among local governments in terms of economic development, economic development-oriented fiscal expenditures crowd out environmental governance-oriented fiscal expenditures, which has led to the consequence that FD can intensify local air pollution and has a positive spillover effect, but the demonstration effect of green technological innovation can well moderate the effect of FD on air pollution. FD in the eastern region has played a positive role in promoting regional air quality improvement. However, its green technological innovation has not played a positive role in reducing emissions, and it plays a significant negative regulatory role in the emission reduction effect led by FD. Finally, the article puts forward policy recommendations in terms of a fiscal decentralization system, green technological innovation, and performance evaluation mechanism.

To promote the precise governance of China’s new-energy vehicle (NEV) industry, this paper quantitatively analyzes 204 policy texts on the NEV industry in China since 2007 and constructs an evaluation system of policy effectiveness from three dimensions of policy attributes, policy objectives, and policy measures to reveal the effectiveness and evolutionary trends of China’s NEV industry policies. In addition, this paper explores the two-way effects of different types of policy measures on the NEV supply and demand markets through an econometric model to reveal the differential impact effectiveness of various policy instruments in China’s NEV industry. The results indicate that China’s NEV industry has changed from “government-driven” to “government-driven + market-driven”, and the multi-sectoral policy coordination needs to be further improved; the dynamic evolution over the years reveals a similar pattern of change in the total effectiveness of policy issuance as influenced by the number of policies; the quantity of patents in China is large but the quality of patents is insufficient, and an overall problem of low level of core technology is being faced; taxation and subsidy measure, technical innovation measures, social guidance measures, and environmental support measures all effectively promote the development of the supply-side market, while taxation and subsidy measures, social guidance measures and legal regulation measures can better promote the development of the demand-side market; the impact of financial support measures on both supply and demand-side markets is not significant.