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

The top ten cities with severe haze in China in 2017 are: Xingtai, Baoding, Shijiazhuang, Handan, Hengshui, Dezhou, Hecheng, Liaocheng, Langfang, and Tangshan.

In 2017, their annual average values ​​of pm2.5 (micrograms/cubic meter) were: 131.4, 127.2, 122.6, 114.2, 107.6, 106.0, 100.6, 99.8, 99.3, 98.4.

Causes for the formation of haze:

First, the relative humidity of the air near the ground in these areas is relatively high, and the dust on the ground is large. People and traffic on the ground stir up the dust.

The second is that there is no obvious cold air activity, the wind is small, and the atmosphere is relatively stable. Due to the stagnant air flow, tiny particles in the air gather and float in the air.

Third, the sky is clear and cloudy, which is conducive to radiation cooling at night, causing the air with relatively high humidity near the ground to become saturated and condense to form fog.

4. Car exhaust is the main source of pollutant emissions. In recent years, there have been more and more cars in cities, and car exhaust is a factor in smog; 5. Secondary pollution produced by factories; 6. CO2 and other pollutants emitted by heating in winter.

Prevention and control measures:

First, we must control the source. We must not build enterprises with heavy air pollution in the upwind direction of the city, and we must eliminate backward processes and equipment.

Second, we must control enterprises with serious air pollution so as to reduce the emission of waste gas. Promote the use of clean energy such as natural gas, hydropower, wind energy, nuclear energy and solar energy, and minimize the use of highly polluting fuels such as coal, heavy oil and waste.

Third, develop public transportation, reduce traffic flow, and call on the public to save energy and reduce emissions, use energy-saving home appliances, take more public transportation, and ride bicycles.

Hazards:

Due to the small particle size of PM2.5, it can adsorb toxic and harmful chemicals, bacteria, viruses and other microorganisms, and can enter the human respiratory tract with breathing, irritating the human nasal mucosa, Sensitive parts such as bronchial mucosa, or being directly inhaled into the lungs, can cause diseases including asthma, bronchitis, and cardiovascular disease. Another hazard of PM2.5 is that it is an important transmission vector for pathogenic microorganisms (such as SARS, H1N1, Legionella, etc.) and will contribute to the spread of diseases.