环境规制的水污染减排效应研究——来自水污染物排放标准提升的微观证据

Study on the Effect of Environmental Regulation on Water Pollution Reduction:Micro Evidence from the Stricter Water Pollutant Emission Standards

在加快构建现代环境治理体系、打好污染防治攻坚战的大背景下,污染物排放标准制度作为我国环境管理的基础性制度,其“以新代旧、以严替宽”的动态提升是我国工业减排的主要驱动力。基于手工搜集的中国水污染物排放标准信息构建政策变量,利用2001—2014年中国水污染企业微观数据,采用多期双重差分法系统研究标准提升的减排效应、作用机制和差异化政策效应。研究发现:标准提升显著降低了以化学需氧量为表征的企业水污染排放,基于多种方法开展的稳健性检验结果表明这一结论是可靠的。机制分析显示,企业减排没有以减产停产为代价,而是通过前端清洁生产和末端污染去除的方式共同实现。异质性分析表明,标准提升的减排效应在制定出台地方标准、标准提升幅度适中、企业达标压力较大的情况下更为明显。为此,应持续完善污染物排放标准体系,有序推进排放标准的覆盖、优化和更新,对不同水平企业分层分级设定排放限值,促使污染企业“劣者趋良、良者趋优、优者更优”。

Under the background of the construction of a modern environmental governance system and further promoting the nationwide battle to prevent and control pollution,the emission standards play an important basic role in China's environmental management.The dynamic update of emission standards can reflect the overall stricter changes in the intensity of industrial environmental regulation in China.Based on information of China's water pollutant discharge standards which is manually built and micro-data of Chinese water polluting enterprises from 2001 to 2014,this research regards the improvement of standards as a quasi-experiment,using the Staggered DID to study how stricter standards affect the emissions and its internal mechanism as well as heterogeneous effect.The study found that stricter standards significantly reduced COD emissions of enterprises,and the robustness test results based on a variety of methods showed that this conclusion was reliable.Mechanism analysis shows that emission reduction is not at the expense of"reducing and stopping production",but mainly through cleaner production and end-of-pipe treatment.Heterogeneity analysis shows that the emission reduction effect of stricter standards is more pronounced when local standards are issued,the standard increase is moderate,and the pressure on enterprises to meet standards is high.Therefore,it is necessary to continue to improve the construction of emission standards,and promote the coverage,optimization and update of emission standards regularly and orderly.Optimize the existing emission standards,and formulate for different types of enterprises at different levels,so as to promote all kinds of polluting enterprises to achieve better goals.