自贸区设立改善了大气环境状况吗?

Has the establishment of free trade zones improved the atmospheric conditions?

中国自由贸易试验区作为新时代对外开放的新窗口,是推动经济高质量发展的重要举措,而在此过程中污染防治是必须跨越的一道重要关口。文章以中国自由贸易试验区设立为“准自然实验”,考虑其政策辐射效应,创新性利用空间双重差分法一般分析范式,选取2008—2017年中国环保重点城市数据为样本,系统考察中国自贸区设立对大气污染的影响,并深入分析其空间维度的异质性与作用机制。研究发现,中国自由贸易区的设立能够显著降低城市的大气污染浓度,在使用空间双重差分法考虑自由贸易区设立的政策辐射效应后,其有效降低城市大气污染物浓度12%~17%,而传统双重差分法估计结果仅为7%;自由贸易区设立对邻近非试点城市的大气污染状况具有显著改善作用,在考虑自由贸易区中心辐射影响范围后,发现随着研究半径的增加,其平均空间溢出效应呈现倒“U”型曲线,最佳政策溢出效应半径约为200 km,而试点城市之间的政策溢出效果不佳;自由贸易区设立不仅能够通过推动试点城市的产业结构优化和绿色技术创新的方式改善本地大气环境状况,还能通过推动邻近非试点城市的产业结构优化和绿色技术创新方式产生溢出效应,助力非试点城市的大气环境状况改善。上述结论在空间平行趋势检验、安慰剂检验等一系列稳健性检验后依旧成立。文章对自贸区政策是否能够真正服务于新时代经济高质量发展这一关键问题给出了直接回答,并为进一步扩大对外开放,打赢污染防治攻坚战,助推中国经济高质量发展提供有益的政策启示。

As a new window for opening up in the new era,the establishment of free trade zones is an important measure for China to pursue high-quality economic development.How to prevent and control pollution has to be seriously taken into consideration in this process.We viewed the establishment of free trade zones in China as a ’natural experiment’.Considering its policy radiation effect,we used the spatial difference-in-differences method to study the influence of China’s free trade zones on air pollution and analyzed the heterogeneity and function mechanism of spatial dimension based on data of environmental protection cities in China from 2008 to 2017.The results showed that the free trade zones significantly reduced the concentration of air pollution in the Chinese cities.Considering the spatial difference-in-differences method based on the radiation effect of the policy,this study found that China’s free trade zone policy could effectively reduce the urban air pollution from 12% to 17%,while the result of traditional difference-in-differences was only 7%.The establishment of free trade zones had significant improvement effect on the air pollution of neighboring non-pilot cities.Considering the radiation effect in the centers of the free trade zones,we found that the average spatial spillover effect presented an inverted ’U’curve with the increase of the radius.The optimal policy spillover effect radius was about 200 km.However,the policy spillover effect between pilot cities was poor.The establishment of free trade zones could not only improve local atmospheric conditions by promoting the optimization of industrial structure and green technology innovation in pilot cities,but also improve the atmospheric conditions of non-pilot cities by promoting the optimization of industrial structure and green technology innovation in neighboring non-pilot cities.The above conclusions were still valid after considering a series of robustness tests such as spatial parallel trend test and placebo test.The paper provides a direct answer to the key question of whether the free trade zone policy can actually support the high-quality economic development of the new era.Moreover,it also provides useful policy implications for further opening-up,winning the battle of pollution control,and boosting the high-quality economic development of China.