Experts in the process of heavy air pollution in Beijing, Tianjin and Hebei interpret the causes of pollution
China Network November 13th According to the official Weibo news of the Ministry of Ecology and Environment, according to the latest forecast results of China National Environmental Monitoring Center, from November 13th to 15th, Beijing-Tianjin-Hebei and its surrounding areas and Fenwei Plain will be affected by unfavorable meteorological conditions, and a heavy air pollution process will occur. The National Joint Center for Prevention and Control of Air Pollution organized expert consultation in time, and invited Chai Fahe, the chief scientist of atmospheric environment of china environmental science Research Institute, to interpret the sources and causes of this pollution process.
I. General situation
Since November 12th, the meteorological conditions in Beijing-Tianjin-Hebei and its surrounding areas and Fenwei Plain have gradually deteriorated, and pollutants have accumulated slowly. At 0: 00 on the 12th, the concentration of PM2.5 in Anyang first reached hourly heavy pollution, and then the concentration of PM2.5 in Zhengzhou, Xinxiang, Xingtai and other cities reached hourly heavy pollution, and gradually developed northward. As of 22: 00 on the 12th, the highest hourly concentration of PM2.5 in the area was 206 μ g/m3, which appeared in Kaifeng (19: 00 on the 12th). The maximum hourly concentration of PM2.5 in Beijing reached 150 μ g/m3 (at 21: 00 on the 12th).
According to the latest forecast results of China National Environmental Monitoring Center, from November 13th to 15th, Beijing-Tianjin-Hebei and its surrounding areas and Fenwei Plain will be affected by unfavorable meteorological conditions, and the air quality of some cities in Beijing, Tianjin, central and southern Hebei Province, eastern and southern Shanxi Province, western Shandong Province, northern Henan Province and Guanzhong area will reach serious pollution for two to three consecutive days, and some cities may have serious pollution. Beijing’s air quality was dominated by moderate to heavy pollution on the 13th, and it may reach heavy pollution on the 14th, and it may maintain heavy pollution on the morning of the 15th, and it is expected to improve around noon.
Second, the cause analysis
1. Meteorological conditions
From the 12th, the near-surface of Beijing-Tianjin-Hebei and its surrounding areas turned to weak southerly winds, and the nighttime wind speed decreased, the humidity increased, and the atmospheric diffusion conditions deteriorated. In most cities, static stability, high humidity and inversion occurred, and pollutants gradually accumulated. Meteorological departments in various places have issued fog warnings respectively. On the night of the 12th, Beijing was affected by the superposition of the inversion temperature in the middle atmosphere and the high humidity near the ground, which was beneficial to the rapid transformation and moisture absorption growth of secondary particles and pushed up the concentration of PM2.5.
2. Pollution discharge
At present, the emission of air pollutants in the industrial and transportation fields is still at a high level, and the amount of various types of construction is extensive, and the control of dust is still not in place. At the same time, the northern region has entered the early winter season, the weather is getting colder, the urban built-up areas have started heating in winter, and rural areas have also started self-heating. The regional pollutant emissions have increased, and the air pollutant emissions have entered the highest season of the year.
Third, early warning and emergency response
In response to the pollution process from the 13th to 15th, the Ministry of Ecology and Environment has sent letters to the people’s governments of Beijing, Tianjin, Hebei, Shanxi, Shandong, Henan and Shaanxi provinces (cities), suggesting that all localities should start early warning of heavy pollution weather at corresponding levels according to the local air quality forecast and take emission reduction measures in advance to effectively reduce the impact of heavy pollution weather. As of 8: 00 on the 13th, 25 cities in the above-mentioned provinces and cities issued early warnings, 8 cities in Hebei Province and 6 cities in Henan Province issued orange warnings, and started Class II emergency response measures; Eleven other cities issued yellow warnings and launched Class III emergency response measures, including Beijing at 8: 00 on the 13th and Tianjin at 12: 00 on the 13th.
According to the preliminary calculation, the emergency emission reduction measures taken for this heavy pollution process have reduced the emission of primary particulate matter, SO2, NOx, VOCs and other pollutants by about 10%-15%.
Fourth, forecast and forecast
According to the latest air quality forecast results of China National Environmental Monitoring Center in consultation with provincial monitoring centers in Beijing, Tianjin and Hebei and surrounding areas, around noon on November 15, the regional pollution process was slowly reduced due to the influence of cold air, and the pollution zone moved slowly to the south as a whole. The central area of Beijing, Tianjin and Hebei improved, and the southern part of Beijing, Tianjin and Hebei, the western part of Shandong and the northern part of Henan may maintain heavy pollution due to pollution transmission. It is expected that the pollution process will end on November 16.
From November 16 to 18, due to the continuous influence of cold air, the diffusion conditions are favorable, and most areas in the region are mainly excellent, and some areas may be slightly polluted.
It is estimated that the air quality in Beijing will improve around noon on November 15th, with good to light pollution as the main pollution throughout the day and excellent pollution from 16th to 18th.