China News Service, May 15th, He Kebin, deputy director of the National Air Pollution Prevention and Control Center and an academician of the Chinese Academy of Engineering, said today that the basic reason for the frequent occurrence of heavy air pollution in autumn and winter in Beijing, Tianjin, Hebei and the surrounding areas is a high level that exceeds 50% of the environmental capacity. Intensity of emissions.

Data Map: On December 1, 2018, the Daning Water Storage Reservoir in Fangshan, Beijing, in the haze. China News Agency reporter Cui Nanshe

  On the morning of May 15, the Ministry of Ecology and Environment held a press conference. He Kebin said that as of now, the causes of heavy air pollution in autumn and winter in Beijing, Tianjin, Hebei and the surrounding areas have been figured out, which can be summarized into the following four aspects.

  First, high-intensity emissions that exceed the environmental capacity by more than 50% are the root cause of heavy air pollution in autumn and winter in Beijing-Tianjin-Hebei and surrounding areas. We know that in addition to the sulfur dioxide pollutant, the actual emissions of other major pollutants in the "2 + 26" cities exceeded 50% of the environmental capacity, and the emission intensity reached twice to five times the national average. And in the heating season increased by about 30% of emissions. In addition, there are a large number of steel, coking, glass and other enterprises in this area. The main production process is uninterruptible, so it has no way to achieve substantial emission reductions in the short term.

  Second, the general background of climate warming in recent years has resulted in unfavorable meteorological conditions, which is an important cause of the formation of weather processes that cause heavy atmospheric pollution in autumn and winter in the region. In Beijing, Tianjin, Hebei and the surrounding area, it is a semi-closed terrain located on the east side of Taihang and the south side of Yanshan. It belongs to the weak wind area. The "warm cover" phenomenon we often talk about in autumn and winter often causes the accumulation of pollutants. In the current situation where the pollutant emission intensity is relatively high, once a relatively long period of high humidity and extreme conditions occur, the environmental capacity of the entire region will be further reduced by more than half, which will induce a large-scale heavy pollution process.

  Third, the high concentration of nitrogen oxides and VOCs cause the atmospheric oxidizability to be strong, which is a key factor for the rapid growth of the secondary PM2.5 concentration during heavy pollution. The monitoring results show that both the PM2.5 concentration and the proportion in this area Significant decline. The atmospheric oxidation in Beijing, Tianjin, Hebei and surrounding areas is generally high, and the secondary conversion rate in heavily polluted areas has increased.

  Fourth, the regional characteristics of atmospheric pollution in this area are outstanding. Beijing-Tianjin-Hebei and the surrounding areas are in the same air flow field. The mutual influence of atmospheric pollution is very obvious. During heavy pollution, pollutants are mainly transmitted to Beijing along the southwest, southeast and eastward channels. The average contribution of regional transmission can reach 45%, and even 70% in individual pollution processes.

  He Kebin pointed out that during the Spring Festival this year, the heavily polluted weather process in Beijing, Tianjin, Hebei and surrounding areas just confirmed the above research results and research conclusions.