《大气污染防治行动计划》实施效果评估:双重差分法

《大气污染防治行动计划》被认为是史上最严格的一项空气污染治理政策。主要目标是控制区域PM 2.5和PM 10等污染物的排放量,明确规定了全国地级及以上城市可吸入颗粒物浓度比2012年下降10%以上,该政策始于2013年9月,于2017年底结束。为了科学检验《大气十条》的政策影响效应,选取该政策执行期间(2013—2017年)的125个地级及以上城市,包括72个处理组和53个控制组进行准自然试验,运用双重差分法检验该政策对控制主要空气污染物PM 2.5、PM 10、SO 2、NO 2、CO和O 3月均排放量的影响,并运用平行趋势检验、反事实检验等方法进行了稳健性检验。描述性统计结果显示:PM 2.5、PM 10、SO 2、NO 2和CO的月均排放量都得到了显著降低,其中PM 2.5和PM 10的降幅分别是36.33%和31.87%。京津冀、长三角、珠三角等区域PM 2.5浓度分别下降39.6%、34.3%、27.7%,三大区域PM 10的降幅分别为38.3%、31.1%、21.9%,其中,北京市PM 2.5月均浓度为57.33μg/m^3。但是O 3的排放量下降效果不显著,其含量不降反增,成为我国空气质量新的威胁。回归结果说明,该政策对试点城市大气中PM 2.5、PM 10、SO 2、NO 2和CO的排放量下降产生了显著影响,在1%显著性水平上,月均浓度分别下降685.14%、650.72%、479.05%、359.55%和7.06%。因此,总体上可以认为该项政策已经达标完成,控制了主要空气污染物的排放量。但是分解不同污染物、分区域或者是具体到不同城市的空气质量绝对值仍未达到国家控制标准。最后提出执行科学精细的空气质量监督管理制度和空气污染治理的长效政策等建议。

Assessment of the Air Pollution Prevention and Control Action Plan in China:a Difference-in-Difference analysis

China’s Air Pollution Prevention and Control Action Plan,effective between September 2013 and the end of 2017,is considered to be the most stringent air pollution control plan in the Chinese history.Its main objective was to control regional pollutant emissions.The Difference-in-Difference method(DID)is a widely used impact assessment method in this field.In order to scientifically test the policy impact of the Air Pollution Prevention and Control Action Plan,125 cities at or above the prefecture level during the period of implementation of the policy(2013-2017),including 72 treatment groups and 53 control groups,were selected to conduct quasi-natural experiments,and the monthly average emissions of each of the major air pollutants(PM 2.5、PM 10、SO 2、NO 2、CO and O 3)were tested by the DID method.The results show that the monthly average emissions of PM 2.5、PM 10、SO 2、NO 2、CO were significantly reduced,with PM 2.5 and PM 10 decreasing 36.33%and 31.87%respectively.The regional concentration of Beijing-Tianjin-Hebei region,Yangtze River Delta and Pearl River Delta decreased by 39.6%,34.3%and 27.7%respectively,However,the O 3 emissions increased,which became a new threat to the air quality in China.The DID regression results show that at the 1%significant level,the monthly average concentration decreased by 685.14%,650.72%,479.05%,359.55%and 7.06%respectively.Therefore,it can be considered that the policy has fulfilled its objectives and controlled the emissions of major air pollutants.However,the absolute value of air quality for decomposition of different pollutants,sub-regions or specific to different cities has not yet reached the national standards.Finally,this paper put forward some suggestions on the implementation of a scientific and sophisticated air quality supervision and management system and long-term policies for air pollution control.