The client of Chinanews.com, May 11th. On the evening of the 11th, strong wind and sand weather appeared in the urban area of ​​Beijing. The Beijing Meteorological Observatory upgraded the warning signal of strong wind yellow at 21:30 on May 11th: it is expected that there will be The northerly winds of level 5 and 6 and the gusts of around 9 are accompanied by sand and dust. Real-time data from the Beijing Environmental Monitoring Center shows that at 21:00 on the 11th, PM10 became the primary pollutant in Beijing's air, with a concentration of 500, and PM10 in the northwest region was significantly higher. The air quality is seriously polluted, and it is expected that the wind power in Beijing will gradually decrease after 23:00.