What are the top ten cities with severe smog in China?

20 17 The top ten cities with serious smog in China are Xingtai, Baoding, Shijiazhuang, Handan, Hengshui, Dezhou, Lianhua Town, Liaocheng, Langfang and Tangshan.

In 20 17 years, their annual average values of pm2.5 (μ g/m3) are 13 1.4, 127.2, 122.6,1/kloc-respectively.

Causes of smog formation:

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 agitated 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, the tiny particles in the air gather together 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.

Preventive and control measures:

First, it is necessary to control the source, not to build enterprises with heavy air pollution in the upwind of cities, and to eliminate backward technologies and equipment.

The second is to control enterprises with serious air pollution and reduce emissions. Advocate the use of clean energy such as natural gas, hydropower, wind energy, nuclear energy and solar energy, and try to use less polluting fuels such as coal, heavy oil and waste.

Third, develop public transportation, reduce traffic flow, and appeal to citizens to save energy and reduce emissions, use energy-saving household appliances, take public transportation and travel by bike.

Danger:

Due to its small particle size, PM2.5 can adsorb toxic and harmful chemicals, bacteria, viruses and other microorganisms, and can enter the human respiratory tract with breathing, stimulate sensitive parts such as nasal mucosa and bronchial mucosa, or directly inhale into the lungs, which will cause diseases including asthma, bronchitis and cardiovascular diseases. Another hazard of PM2.5 is that it is an important carrier of pathogenic microorganisms (such as SARS, H 1N 1, Legionella, etc.). ), which will encourage the spread of diseases.