with the rapid development of information technology, information can be quickly spread through the 1nternet with the click of a mouse. Although it is easy to obtain, it also makes us suffer from false information. From the “salt rumor” to the rumors of water safety in Beijing, all kinds of pseudoscience and pseudoscience are flooding the 1nternet, constantly considering the public’s cognition, and even seriously endangering social order and safety
since October, haze days in Beijing have begun to increase again, and masks have become “hot goods” again. Many masks are under the banner of blocking PM2.5 when they are promoted. So, what kind of mask is the most protective against PM2.5? With this problem, the reporter invited experts yesterday to test the filtering effect of seven kinds of masks
experiment
PM2.5 PM2.5 N95 most awesome
before, reporters bought N95 mask, non-woven mask, PM2.5 special mask, activated carbon mask, three ordinary cotton masks, 18 gauze masks, surgical masks and 7 surgical masks on the 1nternet, small commodities market, pharmacy and hospitals respectively. Seven different types of masks were used to simulate PM2.5 filtration
after entering the chemical laboratory of science and Technology Museum, a set of particulate matter analyzer designed according to the national standard has been placed on the operating platform. The front end of this battery like analyzer is the binding cylinder for fixing the mask, while the exhaust fan at the back end of the experimental box mainly plays the role of negative pressure suction of smoke outside the mask. After passing through the mask, the smoke will pass through the laser dust meter in the box, which can accurately record the number of particles with a diameter of more than 1 micron
different from the previous experiments in which printing toner was often used as the experimental pollutant, this experiment chose smaller particle size ignited cigarette dust as the pollutant” The soot is closer to the actual PM2.5 particles, while the print toner is actually PM10 Zhou Youhong explained that this set of instruments was made by Wang lelan, a junior high school student affiliated to Beijing Normal University under her guidance. 1t has been compared with professional testing instruments, and the test results are very reliable
with that, tie the non-woven mask tightly to the air intake cylinder with rubber band, light 3 branches of incense, and start the exhaust fan. The real-time concentration of PM2.5 in the experimental chamber will rise to about 600 μ g / m3. After 15 seconds, three plumes of smoke changed the vertical upward direction and were sucked into the experimental equipment through the mask. After one minute, the concentration of PM2.5 was 495 μ g / m3. This shows that the filtration effect of non-woven mask on PM2.5 particles is negligible
the experimental data of the next 18 layers of medical gauze masks are very similar, but the filtration ratio is relatively high, and the concentration of PM2.5 is stable at 465 μ g / m3 after 1 minute
both plain cotton mask and activated carbon mask produced dramatic results in the experiment. The concentration of PM2.5 increased rapidly to 158 μ g / m3 after 5 seconds, and reached 613 μ g / m3 after 1 minute; 1n the experiment of activated carbon mask, the concentration of PM2.5 quickly exceeded 404 μ g / m3
in the N95 mask and surgical mask experiments, the reporter found that the cigarette dust on the outside of the mask has been floating vertically upward, almost no previous phenomenon of being inhaled into the experimental box. And the dust meter readings have been maintained in double digits, 13 μ g / m3 and 41 μ g / m3 respectively. 1n Taobao, Jingdong Mall and other popular brands of PM2.5 special masks, the experimental results are also good, PM2.5 concentration is 79 μ g / m3
experts
choose the right mask and wear it well
experts interpreted the experimental results” From the data point of view, N95 mask has the best protection effect, and ordinary cotton mask has the weakest filtering ability. ” Besides the poor filtration capacity, the activated carbon particles in the filter layer may become smaller due to friction, extrusion and other external forces, and become fine particles that can be inhaled through the gauze layer
“N95 masks and surgical masks also have disadvantages, which should be considered by the public when choosing them.” Zhou Youhong added that in the experiment, the smoke of Xianxiang was not inhaled into the test box through the mask, indicating that the two kinds of masks had poor air permeability and would feel stuffy after wearing them tightly
professor of School of public health, Fudan University, who has been concerned about PM2.5 for a long time, also said that not all masks can prevent PM2.5. Even if you choose the right mask, you should wear it correctly” The mask should be tightly attached to the face, and the nose and mouth should breathe completely through the filter layer of the mask. ” He said that masks with better filtering effect often have poor air permeability, which will lead to increased respiratory resistance and dyspnea. Therefore, people with respiratory diseases should choose carefully
experts suggest that the type of mask should be selected according to the exposure time in the polluted environment and their own conditions. 1f the outdoor travel time is very short, you can choose a mask with good filtration to achieve the best effect. For those who have been outdoors for a long time, they should choose masks with both permeability and filtration according to their own physical conditions. But no matter what kind of mask you choose, you should reduce outdoor activities in haze weather. When wearing a mask, you should shave off your long beard, and try to reduce facial muscle activity and speech to prevent the gap between the mask and the face
uncover secrets
piggy beak arch is conducive to protection
experts told reporters that most masks with better PM2.5 filtering effect have added special filtering materials. N95 mask production of a company told reporters, N95 mask inside a layer of special material filter cloth. According to the technical specifications, the filter material can filter particles of more than 300 nm
a person in charge of a domestic technology company specializing in the production of PM2.5 protective masks told reporters that the masks produced by the company are also embedded with special Kanglun fiber, and the filtration level is abou2.5 microns. 1n addition, microfiltration technology has also been applied to PM2.5 masks
experts also said that in actual use, masks with better PM2.5 filtration performance are generally of three-dimensional design, that is, the product has a pig shaped arch. This design can make the mask fit the face better. The ordinary plane cutting mask will have a gap with the face after wearing
extended interview
more people wear masks and less people choose them
of the 300 pedestrians and cyclists passing outside Dongsi subway station and Chegongzhuang subway station, 75 people wear various masks. Among them, the disposable non-woven mask and activated carbon mask with metal nose clip are the most worn. Among the young people, the number of wearing cotton masks with various patterns is the most
“what do you wear a mask to prevent?” 1n the face of reporters’ questions, 30 of the 35 respondents answered “PM2.5 prevention”. However, when the reporter continued to ask how to choose the mask to prevent PM2.5, most people shook their heads and said they didn’t know how to choose, and they didn’t know how the mask they were wearing could prevent PM2.5 invasion. When choosing masks, most people will choose the style recommended by the store sales staff, but their protection principle and function are not clear
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