Professional instrument measurement report filter PM2.5 9 masks which is good

At present, PM2.5 index frequently pops up in many places, air pollution has become a topic of concern to everyone, but it also whipped up the “mask economy,” and the variety of masks on the market has been varied. The Shanghai traffic police has recently issued a new one. "Invisible mask" - U-shaped stuffy nose, known as the filter can clean air.

So, what kind of mask filter PM2.5 effect is the most reliable? This month's "Curious Lab" selected 9 kinds of masks commonly used in the market to conduct PM2.5 filter evaluation.

Mask anti-PM2.5 heavy material rather than the thickness of 4 layers of cotton gauze surgical mask most practical

The masks currently on the market are generally divided into four categories:

The first type is an ordinary mask: it is generally a 3-layer type. Now there are many that are advertised as capable of preventing PM2.5 type, and generally have 5 layers;

The second category is medical masks: There are disposable three-layer non-woven masks (blue masks worn by doctors and nurses at present), four-layer gauze masks and twelve layers of thick gauze masks worn by old doctors. White thick gauze masks are now largely unused);

The third category is professional masks: N95 masks and KN90 masks, respectively, are basically 6 layers thick (N95 and KN90, representing the effect of filtering PM2.5 particles reached 95% and 90%, respectively);

The fourth category is a new type of special-shaped masks: U-shaped stuffy nose “invisible masks” and gas mask masks.

The instrument for this experiment is a "microcomputer laser dust meter" that mainly detects PM2.5 concentration. The test site was in Ningbo Huaxuan Detection Technology Co., Ltd. – in a 15-m2 conference room, all doors and windows were closed, cigarettes lit, and the PM2.5 concentration accumulated to 600 μg/m3 (almost equivalent to the extremely heavy pollution level in Beijing. ) After wrapping the various masks on the collection port of the microcomputer laser dust meter, compare the gap between the data before and after to see how many masks can block the PM2.5. The result is as follows -

(Note: The measured KN90 rejection rate of 6 layers is only 37.21% because the KN90 mask is curved and is not densely packed with the inspection instrument collection port, resulting in inaccurate measured data.)

From the data point of view, different masks can filter PM2.5 more or less, but it does not depend on the thickness; for example, the thickest 12-layer gauze masks are the worst, only 17.7. %.

Wang Limin, deputy director of the Respiratory Department of Hangzhou First People’s Hospital, said that the mask filter PM2.5 is heavy in material. “The disposable three-layer non-woven masks and 12-layer gauze masks in the hospital can only block some viral bacteria with respiratory infections, but they are powerless for PM2.5. Professional masks have a special layer of filtering material. There is also a nose clip, which is tightly attached to the nasal cavity and is tightly sealed. When doctors enter SARS and other infectious wards, they wear N95 masks."

"Curious Lab" cut a variety of masks found, 5 layers of anti-PM2.5 general masks, 4 layers of cotton gauze medical masks, professional masks, etc., there is a layer of N95 filter cloth, while other masks only added a few layers Gauze, or add a layer of sponge, or add a layer of activated carbon, filtering PM2.5 effect is not good.

Although professional masks such as the N95 and KN90 have good protective effect, they are not comfortable and may feel boring over time.

"Practically speaking, N95 masks are poorly breathable, and the toxic and harmful gases exhaled by the lower respiratory tract cannot be discharged outside. This is equivalent to repeated breathing and is not suitable for long-term wear," Dr. Wang Limin said.

As for the U-shaped stuffy nose 'invisible mask', although the blockage data also looks okay, but the blocker does not block the mouth, the actual effect is to be greatly reduced, and it needs to change often, otherwise it is easy to breed bacteria; and gas mask masks, The shape is too exaggerated and wears like a "biochemical warrior."

Therefore, the comprehensive comfort, filtration PM2.5 effect and price and other factors, "Curious Lab" believes that in daily life, 4-layer cotton gauze medical mask is the most economical and practical.

Windows in the house are not safe at home under ventilation of indoor and outdoor PM2.5 is almost no difference

When the haze is serious, the most commonly heard advice is to go out and many people think that hiding in the interior, PM2.5 concentration will be less than the outdoor - this is actually a big misunderstanding, unless you never open the window!

"Curious Lab" and Dr. Li Jintao from the CDC of Hangzhou City carried out a monitoring of the living environment with a professional portable PM2.5 tester.

On the day of the test, the concentration of PM2.5 in the Dengxin District of Hangzhou’s Xiacheng District was 146 μg/m3, which was classified as “heavy pollution” in accordance with national standards for air quality; we randomly selected a 15-m2 bedroom in Wick Lane District. , In the window ventilation conditions, the measured indoor PM2.5 concentration of 142 micrograms / cubic meter - the gap between the house and the outside is almost negligible!

Dr. Li Jintao said that at present, the country does not have uniform regulations for indoor PM2.5. Under normal circumstances, outdoor air must account for more than 55% of the indoor impact. “With doors and windows unobstructed, there is little difference between indoor and outdoor.”

Water basin adsorption method:

That is, put a pot of water in the room and rely on water to absorb the tiny PM2.5 in the air. This principle is just like spraying water to attract dust.

Dr. Li Jintao from Hangzhou CDC said that this method increases the air humidity through volatile water vapor and speeds the deposition of dust. However, the indoor air flow is slow and the evaporation of a pot of water is very slow. The actual effect is not obvious. It is better to use a humidifier.

Plant adsorption method:

Put a pot of plants indoors, relying on the leaves of plants to attract dust.

"The Curiosity Lab" has done experiments, using green plants to adsorb the formaldehyde of the room is not reliable. Dr. Xu Bingjun of Zhejiang Provincial Environmental Monitoring Center also believes that the effect of plant adsorption is not great, because PM2.5 is very small, it can stay in the air for more than ten days, and it wants to rely on green plants to absorb PM2.5, the effect is not obvious.

Open air conditioning method:

Some netizens said that the air conditioner is like a vacuum cleaner. Its filter can absorb indoor dust.

In the same bedroom of 15 square meters, the PM2.5 content was measured at 142 micrograms/cubic meter; five minutes after the air conditioner was turned on, the indoor PM2.5 was reduced by 17 micrograms/cubic meter.

Dr. Li Jintao from Hangzhou CDC said that there is a layer of filter in the air conditioner. Although this filter is not enough to block PM2.5, there is still a part of PM2.5 adsorbed on it.

However, the air-conditioning continued to open for one hour and the PM2.5 concentration in the bedroom remained at around 120 micrograms/cubic meter. The decrease was not significant. In other words, it takes about 5 minutes for air conditioning and 1 hour for air conditioning.

Closed window method:

The window closure method is the most recommended by Dr. Li Jintao.

Dr. Xu Bingjun from Zhejiang Environmental Monitoring Center said that PM2.5 in Hangzhou has obvious seasonal characteristics, with a particularly low concentration in summer and a relatively high concentration in autumn and winter. From a single day, PM2.5 concentrations will be higher at morning and evening peaks. Avoid window opening at this time.

The two experts all said that the window closing method must be effective to withstand outdoor PM2.5, but the doors and windows have been closed and the indoor air quality is not much better. It is best to choose to open the doors and windows for ventilation in the afternoon PM2.5 trough, after the indoor smell has been emitted, then close the doors and windows.