The figures in the material 1 illustrate the characteristics of smog weather in China at present.

The composition of fog is very complex, including hundreds of atmospheric particles. Among them, aerosol particles with a diameter less than 10 micron are harmful to human health, such as urban pollution particles, organic aerosol particles from automobile exhaust, hydrides, sulfides, dust and nitrates. Can directly enter and adhere to the upper and lower respiratory tract and lung lobes of human body, causing rhinitis, bronchitis and other diseases, and can also induce lung cancer in this environment for a long time.

Recently, the relevant person in charge of the Ministry of Environmental Protection analyzed the main reasons for the large-scale haze weather in China: First, unfavorable meteorological conditions caused the continuous accumulation of pollutants. Controlled by the static weather near the ground, the atmospheric diffusion conditions are very poor. Second, under the condition of static weather, motor vehicle exhaust and coal-fired heating in northern winter contribute greatly to the deterioration of air quality.

According to the analysis of relevant experts, there are four main culprits for the smog weather in the north and south, especially in the south: high-altitude strong "atmospheric particulate matter" pollution transmission, man-made emission of "secondary pollution" in many areas, relatively saturated air humidity, and long-term "static weather" in the south.

However, "the external cause is the weather and the internal cause is pollution!" Some interviewed experts believe that the weather factor is the direct factor that causes and aggravates the impact of smog, but the fundamental factor is the continuous emission of pollutants, and the total amount of major air pollution emissions far exceeds the environmental capacity.