The main cause of smog.

Haze is a combination of fog and haze. Smog is very common in cities. In many areas of China, fog and haze are combined as disastrous weather phenomena for early warning and forecasting, which are collectively called "haze weather". Haze is the result of interaction between specific climatic conditions and human activities. Therefore, the formation factors of smog include human factors and climate factors.

Human factors 1, automobile exhaust. The source of toxic particulate matter in cities is firstly automobile exhaust. Cars that use diesel are "habitual criminals" who emit particles. Small cars that use gasoline emit gaseous pollutants, such as nitrogen oxides, which are easily converted into secondary particulate pollutants in foggy days, aggravating smog.

2. Waste gas generated by burning coal for heating in winter in the north.

3. Waste gas from industrial production. For example, metallurgy, kilns and boilers, electromechanical manufacturing, automobile repair and paint and building materials production produce a lot of waste gas from kiln combustion.

4. Dust generated by construction sites and road traffic.

5. Growing particles. The particle size of bacteria and viruses is equivalent to PM 0. 1 ~ PM 2.5. When the humidity and temperature in the air are appropriate, microorganisms will attach to particles, especially oil fume particles. After absorbing oil droplets, microorganisms will transform into more microorganisms, which will increase the growth of biotoxic substances in smog.

6. Dust "smog" will also appear in home decoration, and indoor dust is pervasive, which is not only harmful to the health of staff and users, but also increases the cleaning burden. When the dust is serious, it will also bring many hidden dangers to the decoration project.

Climatic factors 1, horizontal static wind phenomenon increased. The higher the buildings are built in the city, the obstruction and friction of airflow passing through the urban area will be obviously weakened. The increase of static wind phenomenon is not conducive to the diffusion and dilution of suspended particles in the atmosphere, and it is easy to accumulate around urban areas and suburbs.

2. There is an inversion in the vertical direction. The inversion layer is like a pot cover over a city. This inversion phenomenon that the upper air temperature is higher than the lower air temperature limits the vertical movement of the lower air, making it difficult for suspended particles in the air to drift to the upper air and be blocked at the lower air and near the ground.

3. The increase of suspended particles and organic pollutants in the air. With the growth of urban population and industrial development, the number of motor vehicles has surged, resulting in a large increase in pollutant emissions and suspended solids.

Haze protection measures 1, travel protection

Try not to go outdoors in foggy days, or try to reduce the time of going out. Moreover, because the most serious periods of smog are generally from night to midnight and 9- 10 in the morning, it is best to avoid these two periods when smog weather occurs. It is best to choose private cars or subways and other relatively closed vehicles with air purification systems, and keep the air purification system on.

2. Outdoor protection

A practical and effective tool for outdoor protection in foggy days is an anti-fog mask. When wearing a mask, you need to pay attention to: wash your hands before wearing an anti-fog mask and after taking off the mask; When taking off the mask, try to avoid touching the outside of the mask, because these parts may have been polluted by smog particles; When wearing a mask, you feel dizzy, nausea or other discomfort and need to take it off immediately; When the inside of the mask is smelly, dirty or damaged, it should be replaced; According to the severity of smog weather, change the mask in time after wearing the corresponding time; Anti-fog masks should not be cleaned before use.

3. Indoor protection

Try not to open the window in foggy days; When the smog weather dissipates, doors and windows should be properly opened to evacuate indoor particles. When the haze weather is severe, it is necessary to turn on the indoor air purification system, such as an air purifier or an air conditioner with air purification function.