Does industrial collaborative agglomeration improve environmental efficiency? Insights from China's population structure

Nowadays, the development of green economy and the improvement of environmental efficiency have been a hotspot in both academia and industry. Especially, the effect of the collaborative agglomeration of manufacturing and productive services industries on environmental efficiency has drawn attention from Chinese policymakers, during a critical period of industrial transformation and upgrading and ecological civilization construction in China. However, few studies have explored whether and how industrial collaborative agglomeration affects environmental efficiency based on population structure perspective. To bridge this gap, using the methods of the stochastic frontier approach (SFA), the moderating effect of population structure, and the spatial effect, and employing the panel data of 66 cities in eastern China during 2009-2018, this paper studies the effect of industrial collaborative agglomeration on environmental efficiency and measure the fluctuates of influence including population structure. The results show that industrial collaborative agglomeration has the effect of improving environmental efficiency, and both of them have strong spatial spillover effect. Direct effect of the industrial collaborative agglomeration is more significant positive than indirect effect. It indicates that the environmental efficiency is affected by the industrial collaborative agglomeration in both the local region and neighboring regions. In addition, population density, aging and quality play a positive moderate role by strengthening the spillover effect of industrial collaborative agglomeration, while the moderating effect of population urbanization is not significant. Then, the recommendations and policy implications to improve environmental efficiency are put forward based on the research results: optimizing the coordinated governance system of regional ecological environment, accelerating the innovation of industrial value chain, and promoting the sustainable development of industry and ecology with the advantage of population structure.