How is haze formed? Haze weather has a great impact on human health, so it is very important to prevent haze in winter. There are various sources of haze, such as automobile exhaust, industrial emissions, construction dust, garbage incineration, even volcanic eruption, etc. the haze weather is usually formed by the mixture of multiple pollution sources. However, in the haze weather of different regions, the effect of different pollution sources is different.
How is haze formed
In fact, the continuous haze weather and the decline of air quality are not new phenomena this year. In recent years, every autumn and winter, especially after the beginning of winter, China has encountered such situations from time to time. The main causes of haze are as follows:
Impact of meteorological activities
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 vehicles on the ground stir up the dust;
Second, there is no obvious cold air activity, the wind is small, and the atmosphere is relatively stable. Due to the non flow of air, the small particles in the air gather and float in the air;
Third, the sky is clear and cloudless, which is conducive to radiation cooling at night, making the air near the ground with high humidity saturated and condensed to form fog.
Large scale haze weather mainly occurs in the situation of large-scale atmospheric circulation with weak cold air and better water vapor conditions, and the low altitude near the ground is calm wind or breeze. Due to the high humidity and large water vapor in the haze weather, the droplets provide adsorption and reaction sites to accelerate the conversion of reactive gaseous pollutants to liquid particles. Meanwhile, particles are also easy to be used as condensation nodules to accelerate the formation of haze. The interaction between the two can quickly form pollution.
Nonproliferation of pollutants
Fog itself is not pollution, but the atmospheric environment that produces fog is in a relatively stable state. The pollutants in the air are not easy to diffuse outward, resulting in agglomeration effect, which will make the pollution more and more serious. In the same way, under the condition of low air pressure and small wind, the combination of urban pollutants and water vapor in the low-level air will also aggravate the degree of haze. Meteorologists say the fog itself is uneven. Therefore, there will be different levels of haze in the same city.
PM2.5 is the 'culprit' in haze weather. There are several main sources. One is automobile exhaust. In recent years, there are more and more cars in the city, and more and more car exhaust emissions, contributing about 60% to PM2.5 in the air of the city. Second, road dust and construction dust. According to the research, road dust is the main source of PM2.5, accounting for about 20% of PM2.5. Third, the secondary pollution produced by the factory. Fourth, the pollutants emitted by burning coal at low altitude when heating in winter. Fifth, the combustion of biomass (straw, firewood) and the smoke and dust generated by waste incineration are also important sources of PM2.5.
Zhao Huimin, director of the Foreign Affairs Office of the Beijing municipal government, said: 'the cooking habits of the Chinese people have contributed a lot to PM2.5, and we hope that the public will cooperate with us in cleaning the air. "As soon as this statement was made, all circles immediately started to talk about it.
According to the survey results of the Beijing News, cooking does produce PM2.5, but the way of steaming and boiling does not produce much PM2.5, while when frying and frying, PM2.5 soars 8 times to nearly 20 times, reaching the level of serious pollution or even explosion. Among them, cooking produces the most PM2.5, and the PM2.5 value increases from 38 micrograms / m3 at the beginning to 787 micrograms / m3 in five minutes. Therefore, cooking, especially frying and frying, does produce PM2.5, which can not be ignored. Although it may account for a small proportion compared with PM2.5 generated by motor vehicles, coal burning and industrial dust, the public can not underestimate it due to the absorption of harmful substances in lampblack.
Around us, there are many sources of particulate matter that have a much greater impact than cooking, but are often overlooked. For example, dust from urban construction sites, burning of agricultural straw, etc. The inputs from urban road excavation, uncovered roads, construction sites, industrial dust and mineral dust outside the city are also important causes of haze. For example, 11% of the components of PM1 in Beijing -- element carbon mainly comes from urban uncovered roads, construction sites, etc. Haze weather is usually caused by a mixture of various pollution sources. However, in the haze weather of different regions, the effect of different pollution sources is different.
Elements of haze formation
There are various sources of haze, such as automobile exhaust, industrial emissions, construction dust, garbage incineration, even volcanic eruption, etc. the haze weather is usually formed by the mixture of multiple pollution sources. However, in the haze weather of different regions, the effect of different pollution sources is different.
Since ancient times, haze has been caused by human activities or natural phenomena such as slash and burn cultivation and volcanic eruption. However, after human beings enter the era of fossil fuels, haze weather really threatens the living environment and health of human beings. The rapid industrialization and urbanization lead to the rapid consumption of energy, the high concentration of population and the destruction of ecological environment, all of which are the foreshadowing of the formation of haze weather.
The formation of haze has both 'source' and 'accomplice', which is the meteorological condition that is not conducive to the diffusion of pollutants. Once the pollutants accumulate under the static meteorological conditions for a long time, it is easy to form haze weather. There are three elements of haze formation:
The first is the physical basis for the generation of particulate dust. In China, the largest loess plateau in the world, the soil texture is most likely to generate particulate dust particles.
Second, poor movement causes dust. For example, if there is mud flowing to the road after rain or water splashing on the soil in the flower bed in the middle of the road and at the curb of the street, it will cause a lot of dust when it is rotated by the wheel one hour after drying up. Even if these granular materials fall back to the ground, they will be thrown over the city again due to the continuous driving of the car.
The third is that the dust source and movement difference process gather in a certain space, and the particles finally gather with water molecular tuberculosis to form haze. At present, in more than 350 cities in the Loess Plateau of China, the three elements of haze structure are abundant.