Impact of environmental regulation policy on ecological efficiency in four major urban agglomerations in eastern China

Rapid economic development of any country will usually lead to negative environmental impacts. A free market economy cannot fundamentally solve this issue, which requires the guidance and control of the government. The environmental policies of governments can effectively improve the ecological conditions in a region. This study quantifies environmental regulation policies and takes four urban agglomerations in eastern China as the research object to explore the influence of environmental regulation on regional ecological efficiency. First, policies can be divided into policy control, pollution control, ecological protection, and social adjustment by building a Latent Dirichlet Allocation (LDA) model of a policy text library to measure differences in urban policy bias. Next, a slack-based measure (SBM) model was used to measure urban ecological efficiency. Finally, using the qualitative comparison analysis method, the time effect was considered and the ecological efficiency configuration of the entire region was obtained. In addition, contrast analysis was conducted for different path configurations and the reasons of the statuses of the four urban agglomerations were obtained. The results show that policy control, pollution control, ecological protection, and other mandatory policies can significantly reduce the negative environmental effects, especially when the policy controls involve an explicit form of punishment, which is a necessary condition for achieving a high level of ecological efficiency. However, social adjustment means having higher requirements for regional total factor development, which requires improving the environmental awareness of residents and improving corporate social responsibility. Regional differences will mean that areas with a lower level of economic development have a higher intensity of policy control, and the means of policy control should be matched with the level of economic development. In addition, this study proposes some policy suggestions, such as strengthening policy control and pollution prevention, strengthening social regulation, and promulgating environmental laws and regulations according to local conditions.