How is the smog caused?

There are many sources of smog, such as automobile exhaust, industrial emissions, building dust, garbage incineration, and even volcanic eruption. Hazy weather is usually formed by the mixed action of various pollution sources. However, in smog weather in different regions, different pollution sources have different functions.

Haze weather has existed since ancient times, and human activities or natural phenomena such as slash-and-burn and volcanic eruption may lead to haze weather. However, after mankind entered the era of fossil fuels, the smog weather really threatened the living environment and health of mankind. Rapid industrialization and urbanization lead to rapid energy consumption, high concentration of population and destruction of ecological environment, which have laid the groundwork for the formation of haze weather.

The formation of smog has both a "source" and an "accomplice", which is a meteorological condition that is not conducive to the spread of pollutants. Once pollutants accumulate for a long time under static meteorological conditions, it is easy to form haze weather. There are three elements in the formation of smog: one is the physical basic source of particulate matter. China has the largest loess plateau in the world, and its soil texture is the easiest to produce granular dust particles. Second, poor exercise leads to dust. For example, the mud in the garden in the middle of the road and the soil on the roadside stones will flow to the road after raining or splashing water, which will produce a lot of dust after one hour of drying. Even if these particles fall back to the ground, they will be thrown over the city again because of the continuous passing of cars. Thirdly, the basic source of dust and the process of movement difference gather in a certain spatial range, and particles finally gather with water molecules to form haze. At present, in more than 350 cities in the Loess Plateau of China, the three elements of smog structure are quite rich.