What is the cause of smog in Beijing?

The four main causes of smog are motor vehicles, coal burning, heavy industry and dust. As the political center of China, there are a large number of motor vehicles in Beijing. Among such a large group of motor vehicles, there are bound to be motor vehicles whose engines fail to pass the annual inspection, which can not deal with the nitrogen oxides produced by internal combustion engines well. If it is directly discharged into the air, it will cause pollution.

Haze weather is a state of air pollution, and smog is a general term for all kinds of suspended particles in the atmosphere, especially PM2.5 (particles with aerodynamic equivalent diameter less than or equal to 2.5 microns) is considered to be the "culprit" causing haze weather.

With the deterioration of air quality, cloudy days are increasing and the harm is increasing. In many areas of our country, the smog weather phenomenon is combined with fog as an early warning and forecast of disastrous weather. Collectively referred to as "haze weather".

Extended data:

The similarity between fog and haze is sight distance obstacle. However, the reasons and conditions for the formation of fog and haze are quite different. Fog is a large number of tiny water droplets or ice crystals floating in the air, and the formation conditions should have a high water vapor saturation coefficient.

When smog occurs, the relative humidity is not large, but it is saturated in the fog (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur). Smog is caused by pollutants such as automobile exhaust. When the relative humidity is between 80% and 90%, the visibility deterioration caused by blurred vision is caused by the mixture of haze and fog.

When water vapor condensation intensifies and air humidity increases, haze will turn into fog. The difference between haze and fog is that the relative humidity is small when haze occurs, but it is saturated in fog (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur).

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