Why is Changsha foggy these two days?

Monitoring at Changsha Environmental Monitoring Center Station 12 found that 1 1 smog began to appear at 0: 00 at night. Subsequently, the concentration of particulate matter in the air showed a rapid upward trend. By the morning of 12 1 1, the inhalable particulate matter (PM 10) reached 0.459 mg/m3, which was close to the air pollution level most seriously affected by sandstorms in northern Changsha in history. Among them, the concentration of fine particulate matter (PM2.5) in particulate matter reached 0.306 mg/m3.

Experts from Shashi Environmental Protection Bureau admit that it is rare to see similar pollution in the same period of history. The reasons for the preliminary analysis are as follows: First, meteorological factors. According to the data of meteorological department, 1 1 At night, the cold air in the north goes south, and the air humidity in Changsha is high after continuous rainfall, and foggy days begin to appear in the middle of the night. Second, it is influenced by burning straw after harvesting winter wheat in the north. Due to the recent drought in the north, and straw burning in northern provinces and cities such as Shandong, Henan, Anhui, Hubei and Jiangsu (according to the meteorological satellite remote sensing monitoring of the Ministry of Environmental Protection in June 1 1 day, the high-impact area of smoke screen is located in southeastern Henan, north-central Anhui and southern Shandong. ), a large number of floating dust and straw burning smoke carried by cold air southward have directly affected Nanjing, Wuhan and our city in the Yangtze River basin. Affected by both * * *, and Changsha's current atmospheric state is stable, the wind speed is small, and there is an inversion phenomenon at the same time, which is not conducive to the spread of smoke near the ground. Particles deposit to form a sunshade layer, and sunlight refracts and reflects in pollutants for many times, resulting in the sky being khaki and haze weather.

For this kind of "imported pollution from foreign pollutants", experts from Changsha environmental protection department suggested that the general public should reduce going out or wearing masks in the near future. With the decrease of straw burning in the north and the arrival of south wind season in summer, the air quality in Changsha is expected to return to normal.