When is the smog in Chengdu more serious?

The main causes of smog in Chengdu can be divided into man-made reasons and natural climate reasons.

Man-made reasons: automobile exhaust, large vehicles using diesel are "recidivists" who emit PM 10, including buses, shuttle buses of various units and large transport trucks. Sources of toxic particulate matter in cities: firstly, automobile exhaust. Cars that use diesel are "habitual criminals" who emit particles. Although small cars using gasoline emit gaseous pollutants, such as nitrogen oxides, they are easily converted into secondary particulate pollutants in foggy days, which aggravates smog; Waste gas produced by industrial production; Dust from construction sites and road traffic.

Natural climatic reasons:

1. The terrain is unfavorable.

The terrain and meteorological conditions in Sichuan Basin are not dominant in ensuring air quality, and the meteorological threshold for smog formation is relatively low. Professor He Kebin, an academician of China Academy of Engineering and dean of Tsinghua University Institute of Environment, said frankly that the unfavorable terrain conditions are the congenital deficiency that the river basin is prone to haze weather.

2. Terrain: relatively closed

Sichuan is characterized by inland basins, and Beijing-Tianjin-Hebei, Yangtze River Delta and Pearl River Delta are coastal areas. Comparatively speaking, Chengdu is located in the Sichuan Basin, with an altitude difference of 5,000 meters. The meteorological background of mountainous area, hilly area and plain area is quite different and the terrain is relatively closed. Such topographical conditions have brought more troubles to pollution control in Chengdu.

3. There is little wind and light rain in Chengdu, and unfavorable meteorological conditions are another important factor causing haze weather.