According to the results of the Beijing Environmental Protection Department's evaluation of the effectiveness of the red air pollution emergency warning measures, Beijing pollutants have been reduced by 30%. On this basis, the PM2.5 concentration has dropped by 20% to 25%.
Beijing Environmental Protection Agency handed over the "red police" transcript Zhang Dawei, director of the Beijing Environmental Monitoring Center, said that the implementation of the red warning has lasted for about 90 hours, and the concentration of PM2.5 in Beijing has dropped by 20% to 25%. Among the measures, the single and double limit measures contributed the most to the reduction. It is estimated that today's air quality is good for the second grade, and tomorrow is mild. On the 26th and 27th, it is second-class. Before the end of this month, Beijing is expected to be free from heavy pollution.
During this process, the PM2.5 concentration continued to be above 150 Î¼g/m3, and the highest hourly average value in the city occurred at 20 o'clock on the 22nd, which was 421 Î¼g/m3. Among them, the maximum hour value of single station appeared on the night of the 21st, and the hourly concentration at the southwest boundary station of Beijing reached 831 Î¼g/m3.
The level of continuous air pollution is the second this year. The strongest air pollution this year is in late November and early December.
According to Director Zhang Dawei, this year is a strong El Nino year, Beijing is affected by extreme weather, and PM concentration has a significant jump compared with previous years. Air quality in Beijing improved significantly in the first half of the year, but due to meteorological conditions, December was more serious than previous years.
Zhang Xiaoling, director of the Beijing-Tianjin-Hebei Environmental Meteorological Forecast and Warning Center, said that since November, the smog weather in Beijing has been going on for more than two days, mainly due to the small wind speed on the ground. As of the 22nd, the average surface wind speed in Beijing was only 1.8 m/s, and the average annual average was 2.3 m/s. Since November, the number of static wind days with an average daily wind speed of no more than 2 m/s has reached 41 days, compared with less than 30 days in the same period of the year. At the same time, in November, the average relative humidity of the air was 70%, and the annual average was about 50%. Large relative humidity has a great impact on air visibility and will also promote pollutant conversion.
Why is the pollution still in the "red police" but canceled? Why is the smog still there, Beijing "Red Police" has been lifted? Wang Bin, Director of the Emergency Department of the Beijing Environmental Protection Bureau, responded to this hot issue.
First of all, on the 23rd, the air quality was gradually promoted and improved, and the release of the red warning was released to facilitate the public to better arrange work and life, in line with the requirements of the plan.
At the same time, the red warning condition is that heavy pollution will be predicted to last for more than three days (72 hours). This round of heavy pollution from December 19 to 22 for 4 consecutive days, fully in line with the red warning conditions.
Although the pollution on December 23 could not be completely eliminated, from the forecast point of view, the level of heavy pollution has not been reached. Therefore, according to the "Beijing Air Heavy Pollution Emergency Plan", there is no delay red warning.
In addition, air quality is a comprehensive index. Even if it is heavily polluted in the early morning of December 23, if it is blue sky in the latter half of the day, and it will be blue sky in the next few days, it is natural not to continue the red warning.
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