Why is there smog?

Haze is a mixture of fog and haze. When the humidity is high in the morning and evening, there are many components of fog. When the daytime humidity is low, haze is the main force, and the relative humidity is between 80% and 90%. Among them, fog is a natural weather phenomenon, and the water vapor in the air is dense. Although dust is the condensation core, it is generally non-toxic and harmless; The core substances of smog are substances suspended in the air such as smoke and dust. The relative humidity of the air is below 80% and the color is yellow. Gas can directly enter and attach to human lower respiratory tract and lung lobes, which is harmful to human health. The formation of haze weather is mainly man-made environmental pollution, and natural conditions such as low temperature and little wind make it difficult for pollutants to spread.

Smog is caused by automobile exhaust, factory exhaust and fireworks.

The main reasons for the haze weather are as follows:

First, the relative humidity of the air near the ground in these areas is relatively high, and the ground dust is relatively large, which is stirred by people and traffic on the ground;

Second, there is no obvious cold air activity, the wind is small and the atmosphere is relatively stable. Because the air does not flow, tiny particles in the air gather and float in the air;

Third, the sky is clear and partly cloudy, which is conducive to radiation cooling at night and makes the near-surface air with relatively high humidity saturate and condense to form fog.

Fourthly, automobile exhaust is the main pollutant emission source. In recent years, there are more and more cars in cities, and automobile exhaust is a factor of smog;

Five, secondary pollution produced by the factory;

Six, winter heating emissions of carbon dioxide and other pollutants.

Large-scale haze weather mainly appears in the situation of large-scale atmospheric circulation with weak cold air and good water vapor conditions, and the low altitude near the ground is still wind or breeze. Due to the high humidity and high water vapor in foggy days, fog droplets provide adsorption and reaction sites, which accelerate the transformation of reactive gaseous pollutants into liquid particulate components, and particulate matter is also easy to act as condensation nuclei to accelerate the formation of smog, and the interaction between them quickly forms pollution.