What is smog?

Smog/haze (wámáI in English) 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. The economic and social activities of high-density population will inevitably emit a large number of fine particles. Once the emission exceeds the atmospheric circulation capacity and carrying capacity, the concentration of fine particles will continue to accumulate. At this time, if it is affected by calm weather, it is easy to have a wide range of smog.

Haze, as its name implies, is fog and haze. But fog is fog, haze is haze, and fog and haze are very different.

Sulfur dioxide, nitrogen oxides and inhalable particles are the main components of smog. The first two are gaseous pollutants, and the last particulate matter is the chief culprit that aggravates smog weather pollution. They combine with fog and instantly turn the sky gray. The abbreviation of particulate matter is PM, and what Beijing monitors is PM 10, that is, pollutant particulate matter with a diameter less than 10 micron. Sources of toxic particulate matter in cities: firstly, automobile exhaust. Large vehicles that use diesel are "recidivists" who emit PM 10, including buses, shuttle buses of various units and large transport trucks.

Second: the waste gas produced by burning coal for heating in winter in the north.

Third: the waste gas emitted by 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.

Fourth: Dust generated by construction sites and road traffic.

Fog-fog is an aerosol system consisting of a large number of tiny water droplets or ice crystals suspended in the air near the ground.

Haze-Haze (mái), also known as haze, can also make the atmosphere turbid by dust, sulfuric acid, nitric acid, organic hydrocarbons and other particles in the air.

In recent years, with the gradual deterioration of air quality, the phenomenon of haze weather has appeared more and more frequently. They invade the respiratory tract and lungs of the human body unsuspecting, thus causing respiratory diseases, cardiovascular diseases, blood system, reproductive system and other diseases, such as pharyngitis, emphysema, asthma, rhinitis, bronchitis and other inflammation. Long-term exposure to this environment will also induce lung cancer, myocardial ischemia and injury.

The difference between haze and fog

It is because the relative humidity is not large when the smog occurs, but it is saturated in the fog (if there are a lot of condensation nuclei, the relative humidity may not reach 100%, which may lead to saturation).

When the relative humidity is between 80% and 90%, the visibility deterioration caused by blurred vision is caused by the mixture of haze and fog.

cause

"There is actually a difference between fog and haze." Sun Leng, a senior engineer in the Climate System Monitoring Office of the National Climate Center, pointed out that fog refers to the weather phenomenon when the visibility is lower than 1 km due to the condensation of suspended water vapor in the atmosphere. The formation of smog is mainly the result of a large number of suspended particles in the air and meteorological conditions. There are three reasons:

-The phenomenon of static wind in the horizontal direction has increased.

-There is an inversion in the vertical direction.

The increase of suspended particles in the air. With the growth of urban population and industrial development, the number of motor vehicles has soared, and the emissions of pollutants and suspended solids have increased greatly, which directly leads to the decline of visibility.

In fact, dust "smog" will also occur 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. [2]

Danger differentiation

With the deterioration of air quality, cloudy days are increasing and the harm is increasing. In many areas of our country, the smog weather phenomenon is combined with fog as an early warning and forecast of disastrous weather. Collectively referred to as "haze weather". In fact, fog and haze are completely different to some extent.

Haze is harmful to the human body after being inhaled into the human respiratory tract, and long-term severe inhalation will lead to death. [2]

Self - protection

1, open the window less in foggy days.

It is not recommended to open the window for ventilation in the morning and evening in foggy weather. It's best to wait until the sun comes out before opening the window for ventilation.

Step 2 wear a mask when you go out

Step 3 drink more tea

4, the right amount of vitamin D.

5. Eat lightly and drink plenty of water

Eat more vegetables. [3]

ingredient

Haze, fog, haze. There is a great difference between fog and haze. The aerosol system composed of dust, sulfuric acid, nitric acid and other particles in the air causes visual impairment, which is called smog. Haze is haze. When water vapor condensation intensifies and air humidity increases, haze will turn into fog. The difference between haze and fog is that the relative humidity is small when haze occurs, but it is saturated in fog (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur).

Haze weather is a state of air pollution, and smog is a general term for the excessive content of various suspended particles in the atmosphere, especially PM2.5 (particles with a particle size less than 2.5 microns) is considered to be the "culprit" causing haze weather. There are many sources of smog, such as automobile exhaust, industrial emissions, building dust, garbage incineration, and even volcanic eruption. Hazy weather is usually formed by the mixed action of various pollution sources. However, in smog weather in different regions, different pollution sources have different functions.

Many experts in the field of air environmental protection in the United Nations have confirmed that ecological negative ions (small particle size negative ions) can actively capture small particles of dust, make them coagulate and precipitate, and effectively remove dust of 2.5 microns or less, even particles of 1 micron, thus reducing the harm of PM2.5 to human health. The purification effect of ecological negative ions on the air comes from the combination of negative ions with positively charged particles such as bacteria, dust and smoke in the air, which fall into balls to eliminate the harm of PM2.5 Coincidentally, negative ions do Brownian motion (zigzag motion) in the air, and Brownian motion itself is an effective method to eliminate tiny dust. After the combination of negative ions and floating dust, the Brownian motion of floating dust is promoted and the floating dust is eliminated. Experiments show that the smaller the diameter of floating dust, the easier it is to be precipitated by negative ions.

Haze weather has existed since ancient times, and human activities or natural phenomena such as slash-and-burn and volcanic eruption may lead to haze weather. However, after mankind entered the era of fossil fuels, the smog weather really threatened the living environment and health of mankind. Rapid industrialization and urbanization lead to rapid energy consumption, high concentration of population and destruction of ecological environment, which have laid the groundwork for the formation of haze weather.

The formation of smog has both a "source" and an "accomplice", which is a meteorological condition that is not conducive to the spread of pollutants. Once pollutants accumulate for a long time under static meteorological conditions, it is easy to form haze weather.

1. Smog is mainly composed of sulfur dioxide, nitrogen oxides and inhalable particles, which combine with fog to make the sky instantly gloomy. The abbreviation of particulate matter is PM, and what Beijing monitors is fine particulate matter (PM2.5), that is, pollutant particles with a diameter less than or equal to 2.5 microns. This particle itself is not only a pollutant, but also a carrier of toxic substances such as heavy metals and polycyclic aromatic hydrocarbons.

Second, the sources of toxic particulate matter in cities: First, 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.

Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground, which often appears in autumn and winter (which is also one of the reasons for the large-scale haze weather in China in June 20 13), and is the product of water vapor condensation (or condensation) in the air near the ground. The existence of fog will reduce air transparency and worsen visibility. If the horizontal visibility of the target drops below 1000m, the weather phenomenon of water vapor condensation (or condensation) suspended in the air near the ground is called fog. The phenomenon that the horizontal visibility of the target is 1000- 10000 meters is called light fog or mist. When fog is formed, the atmospheric humidity should be saturated (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur). Because the light scattered by fog composed of liquid water or ice crystals has little to do with wavelength, the fog looks milky white or bluish white and gray.

Haze is composed of particles such as dust, sulfuric acid, nitric acid and organic hydrocarbons in the air. It will also make the atmosphere turbid, blur the vision and worsen the visibility. If the horizontal visibility is less than 65,438+00,000 meters, the sight distance obstacle caused by this non-aqueous aerosol system is called haze or dust haze, and the Hong Kong Observatory calls it haze.

Haze difference

Generally speaking, the visibility deterioration caused by atmospheric haze visual blur is caused by haze when the relative humidity is less than 80%, while the visibility deterioration caused by atmospheric haze visual blur is caused by fog when the relative humidity is more than 90%. The visibility deterioration caused by atmospheric haze visual blur is caused by a mixture of fog and haze when the relative humidity is between 80 and 90%, but its main component is haze. The thickness of haze is relatively thick, which can reach about 1-3 km. Haze is different from fog and clouds, and there is no obvious boundary between haze and clear sky. Smog particles are evenly distributed, and the particle size is relatively small, ranging from 0.00 1 micron to 10 micron, with an average diameter of about 1-2 micron. Floating particles are invisible to the naked eye. Because the smog is composed of dust, sulfuric acid, nitric acid and other particles, the longer the scattering wavelength, the more the light ratio, so the smog looks yellow or orange-gray.

There are three elements in the formation of smog: one is the physical basic source of particulate matter. China has the largest loess plateau in the world, and its soil texture is the easiest to produce granular dust particles. Second, poor exercise leads to dust. For example, the mud in the garden in the middle of the road and the soil on the roadside stones will flow to the road after raining or splashing water, which will produce a lot of dust after one hour of drying. Even if these particles fall back to the ground, they will be thrown over the city again because of the continuous passing of cars. Thirdly, the basic source of dust and the process of movement difference gather in a certain spatial range, and particles finally gather with water molecules to form haze. At present, in more than 350 cities in the Loess Plateau of China, the three elements of smog structure are quite rich.

In fact, fog and haze are completely different to some extent. For example, when fog appears, the air is humid; When smog occurs, the air is relatively dry and the relative humidity of the air is usually below 60%. The reason is that a large number of extremely fine dust particles, smoke particles and salt particles float in the air evenly, so that the air with effective horizontal visibility less than 10KM is mixed together. The symbol is "∞". The diurnal variation of haze is generally not obvious. When the air mass changes little and is stable, it lasts for a long time, sometimes exceeding 10 days. Due to the weather phenomena such as smoke, light fog, sandstorm, sand blowing and floating dust, the effective horizontal visibility is less than 10KM due to the influence of a large number of extremely fine dust particles or smoke particles floating in the air. Sometimes it is difficult for meteorological professionals to tell the difference. It is necessary to comprehensively analyze and judge the weather background, sky conditions, air humidity, color and smell, satellite monitoring and other factors to draw a correct conclusion. The weather phenomena of fog and haze can sometimes be converted to each other.

Haze is harmful to the human body after being inhaled into the human respiratory tract, and long-term severe inhalation will lead to death.