What are the causes of smog?

First, the population has been dense for a long time, especially after the reform and opening up, the population has increased greatly, and industrial and agricultural activities have become more frequent, especially the discharge of industrial water, waste and water vapor has doubled. Second, urbanization and the improvement of living standards and the increase of domestic water consumption. These two factors cause the groundwater level to drop and the surface to become drier. However, due to the increase of emissions in autumn and winter, the water vapor content in the air increases, which creates favorable conditions for the formation of smog. Third, the ecology is fragile and lacks the geography of cutting rivers, lakes and mountains. More heat island effects link local microclimates, thus forming a wide range of unfavorable climate.

Fourth, after the reform and opening-up, the agricultural labor has gradually decreased, and mechanized farming and chemical fertilizer topdressing have been widely used. In addition, in previous years, the straw burned for years, the soil organic matter content gradually decreased, the soil moisture content deteriorated, pesticides were widely used, the biological populations of microorganisms, insects, weeds and so on in farmland decreased sharply, and the ecological diversity became fragile, which aggravated the formation of a single climate. Fifthly, in 1950s and 1960s, Haihe River was harnessed, and a large number of rivers were cut and straightened to discharge into Shui Bo. Over the years, the runoff time of rainwater on the surface is getting shorter and shorter. Sixth, urbanization has covered a lot of ground with cement and other buildings, which has contributed to the bad weather such as smog.

In the sixties and seventies, there were many chimneys in urban factories, and every household in rural areas burned coal to cook and keep warm. The sky is blue and the water is clear. The Milky Way and all the stars in the sky can be seen clearly. Now coal burning has been banned in cities, and straw burning is strictly prohibited in rural areas. It is an ancient legend to look at the stars when the smoke is choking. Look at hundreds of millions of cars running all the time on the earth, burning hundreds of millions of tons of gasoline and diesel every day. Tens of millions of tons of waste gas are discharged every day, and since the beginning of human industrialization, various fossil fuels have caused the explosion of harmful substances in the air, resulting in smog. /kloc-in the 0/8th century, large-scale smog weather also occurred in Britain, causing thousands of people to be poisoned and die, so the real cause of smog is actually the negative product of industrialization.