Which is the most effective anti-smog weapon?

From December 16 to 22, many parts of the north suffered the largest regional heavy pollution since the beginning of winter, and Beijing initiated a red warning for heavy air pollution
.

Among them, the haze components represented by PM2.

Fog Cannon Car: The effect of combating smog is actually very limited

Due to its peculiar shape and the shape of a cannon, the fog cannon car was dubbed the "artifact removing haze"
.

In recent years, fog cannon cars have also frequently appeared on the streets of many cities

Working principle: The water is atomized into water mist particles (50 microns-200 microns) the size of dust particles through high pressure, and sprayed from a cannon-shaped air tube.
The wind is strong, the range is long, and the range is wide.
The dust is in the air and the water The fog particles contact and condense and settle, and then achieve the purpose of suppressing dust and purifying the air
.

The large fog cannon can spray water mist 120 meters away and 70 meters high, covering an area of ​​more than 30,000 square meters

Experts say:

Wang Yuesi, a researcher at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, said that the fog cannon car is a water sprayer, which is to spray water efficiently
.

He said that this tool is mainly used for construction sites.

Wang Yuesi believes that the atmosphere is a super fluid with a very fast exchange rate.
Some pollutants will be sprayed down, and other places will soon be supplemented.
The so-called haze control is not understood by atmospheric science
.

If it is used to spray water around the monitoring point, it will affect the monitoring data of the monitoring point and cause the measured data to be untrue

Professor Pan Xiaochuan of the School of Public Health of Peking University said that the smog formed at an altitude of 2,000 meters, and the fog gun vehicle could not reach 200 meters in level
.

Jiang Kejun, a researcher at the Energy Research Institute of the National Development and Reform Commission, believes that sulfides and nitrides, which are originally gases, will chemically react with water to form fine particles and increase PM2.

Indoor air purifier: the efficiency of purifying air is unsatisfactory

The smoggy weather makes more people choose to stay at home without going out, but the indoor air is also not so clean
.

As a result, many people have also purchased indoor air purifiers, but what is the real effect?

Working principle: The common air purifiers on the market are divided into three categories according to their working principles: passive purification, active purification, and double purification
.

Passive purification air purifiers mainly rely on filters to purify
.

The air is drawn into the machine with a fan, and the air is filtered through the built-in filter, which mainly functions to filter dust, peculiar smell, toxic gas and kill some bacteria

Active purification does not rely on filters, but works through ion technology, photocatalyst technology and Plasmacluster plasma technology
.

The main principle is to use static electricity to release negative ions and absorb dust in the air to reduce dust.
At the same time, negative ions also ionize oxygen in the air into ozone, forming "ozone pollution", which is also great for the human body.
Hurt
.

　　Dual purification is to simultaneously purify the air with filters and other technologies
.

　　Experts say:

　　Xie Huaqing, a member of the National Environmental Product Standardization Technical Committee, introduced that air purifiers have two important indicators, one is the amount of clean air, that is, how much air is cleaned by the air purifier
.
The second indicator is "clean life", which is how long it takes to clean indoor polluted air by half
.

　　Xie Huaqing said that it takes a relatively long time for the air purifiers used now to clean out a certain amount of air.
For example, it takes 5-6 hours to get a certain amount of purified air.
"From this process, the role of the air purifier is It's relatively small
.
When the whole nature is haze, the effect is almost weak
.
"

　　N95 protective mask: electrostatic fiber material has better protection effect

　　Anti-smog masks have become a must-have for travel in haze days
.
At present, the universally recognized industry standards for mask protection levels in the world are: NIOSH (National Institute of Occupational Safety and Health) standard; European Union (European Community) EN standard; China GB2626-2006 standard
.

　　However, what is the working principle of anti-smog masks? Can it really play an effective protective role?

　　Working principle: The basic principle of a mask is to filter out harmful substances like a sieve
.
Masks that can protect against fine dust are generally made of non-woven electrostatic materials, and electrostatic fibers are used to absorb inhalable particles in the air
.

　　Experts say:

　　The materials room of the Beijing Institute of Medical Device Inspection has conducted airtightness experiments on several masks in a hospital environment
.
The test results show that ordinary gauze masks have no blocking effect on particles below PM5
.
Ordinary medical masks have an effective effect on the protection of PM4
.
Medical surgical masks and medical disposable masks can block particles larger than 4 microns in diameter
.
The medical protective mask N95 can block most PM2.
5 particles
.
When tested in the airtight laboratory of masks, over 99% of the particles were blocked by medical N95 masks
.

　　However, Yue Weihua, director of the Materials Office of the Beijing Medical Device Inspection Institute, said that their test was a sealing experiment conducted in a hospital environment.
In cities, car exhaust and other emissions are large, and many particles in the air are oily, which will also reduce the mask’s quality.
Actual protection effect
.

　　Since fine dust is also divided into oily and non-oily, the more common 3M masks currently on the market are divided into KR and KN series
.
KR series can filter oily particles, KN ​​series mainly filter non-oily particles
.

　　Urban Ventilation Corridor: Solving the haze problem has only a supporting role

　　Although the wind can blow away the haze, instead of waiting for the wind to come, it is better to build several urban ventilation corridors.
Based on this consideration, the urban air ducts are also placed high hopes in the "anti-haze battle"
.

　　For example, in February 2016, Beijing issued a plan to build five first-level ventilation corridors with a width of more than 500 meters and multiple second-level ventilation corridors with a width of more than 80 meters.
"Road" will be strictly protected, and high-rise buildings are prohibited in the "Wind Road"; Fuzhou City has also planned a ventilation pattern of "One Axis, Ten Corridors, One Door and Multiple Points", and it is clearly written into the "Ecological Fuzhou Master Plan"
.

　　How it works: Rely on the wind blowing into the city under high air pressure to disperse the smog
.

　　Experts say:

　　He Yong, deputy director of the Planning and Research Office of Beijing Urban Planning and Design Institute, said: “The main purpose of the construction of the ventilation corridor system is to improve the wind and heat environment in dense urban areas and alleviate the heat island effect
in the central city .
Under the same premise, ventilation corridors alone cannot solve the haze problem
.
However, it is certain that the formation of a network of ventilation corridors in the central city is effective in improving the microclimate and has a certain auxiliary effect in promoting the diffusion of pollutants
.
"

　　He Yong said that for big cities, it is no longer necessary to re-plan open spaces
.
Therefore, we should try our best to make use of the area with greater ventilation potential, and make it continuous and through
.
Ideal urban air ducts are best combined with natural corridors or natural elements in the city, such as rivers, lakes, ditches and green belts.
The integration of various types of open spaces is conducive to the formation of urban air ducts with sufficient spatial width
.