Abstract
Environmental protection policy serves as an effective means for the government to curb environmental pollution and promote high-quality economic development. The government must weigh the effects of different policy mixes. From the perspective of policy combination, this paper discusses the green effect of environmental protection policy theoretically and empirically. First and foremost, this paper sorts out the reforming time of environmental protection taxes and the situation of the low-carbon pilot city, and puts forward two hypotheses. Furthermore, by referring to the environmental protection tax, the policy for the low-carbon pilot city, and the urban air quality indicator from 2014 to 2020, this paper explores the green effect of the environmental protection policy and further validates the consolidation effect of the policy mix on the green effect. The study reveals a significant decrease in the air pollution level in regions with higher standards for levying an environmental protection tax. The conclusion remains robust via parallel trend testing and substitution of the subject variables. Furthermore, an analysis of the policy mix of an environmental protection tax indicates that the policy mix of an environmental protection tax and low-carbon city produces a significant green effect, which not only curbs air pollution but also reduces greenhouse gas emissions. An in-depth analysis shows that an environmental protection tax has the best green effect in the first and second areas of a low-carbon pilot market. The synergies of low-carbon pilot effects are higher in areas with low and middle tax rates.