Can national environmental protection supervision and control have a lasting impact on corporate production efficiency? - an empirical study based on the multi-phase difference-in-difference model.

National environmental protection supervision and control has become essential means to regulate the environmental behavior of enterprises. Furthermore, the optimization, promotion, and sustainability of relevant policies are key topics of inquiry. Taking the implementation of national environmental protection supervision policies as the time series, this paper studies the impact of national environmental protection supervision and control on corporate production efficiency. It uses the multi-phase difference-in-difference (DID) method and explores the sustainability of said policies. Results indicate that, first, national environmental protection supervision and control can considerably enhance corporate production efficiency, and green technology innovation plays a vital role as an intervening variable. Second, national environmental protection supervision and control can only boost the increase in corporate production efficiency in the short term, and the impact will no longer be noticeable in the third year. This paper provides a decision-making basis for constantly boosting and revising national environmental protection supervision and control policies and stimulating green technology innovation.