Wear activated carbon mask to block PM2.5 particles
Which mask is best for blocking PM2.5? The reporter passed the professional test to draw conclusions Wearing activated carbon masks These days, Beijing suffered the fourth smog weather this month. In order to be healthy, people began to adopt protective measures, and various masks were also popular. So, which mask can effectively block PM2.5 particles? Yesterday, the reporter walked into the Environmental Measurement and Control Optimization Research Center of the China Academy of Building Research with four kinds of masks purchased from the market. After conducting professional tests, the masks with activated carbon filter screens are more suitable for wearing in foggy weather. On the contrary, the gauze mask has almost no blocking effect on the fine particles. Investigation: gauze masks sold out of stock "Sorry, the gauze mask has been out of stock for several days." Yesterday afternoon, at a pharmacy in South Beach, a salesperson answered the reporter. According to her observation, in the past few days, there have been a lot of people who bought masks. "Thick gauze masks are the most popular." By contrast, disposable masks are not so popular. In some online stores, the N95 and the KN90 mask with activated carbon filter are not popular. The reporter saw that some online stores actually sold 78,454 N95 masks in 30 days. Experience: Masks with activated carbon filter have poor comfort Before the experiment began, the reporter purchased four kinds of masks: 24 layers of gauze masks, disposable medical masks, N95 masks, and KN90 masks with activated carbon filters. The reporters wore the experience of wearing these four masks. It was found that wearing N95 masks and KN90 masks would result in poor breathing, and the comfort would be worse than gauze masks and disposable medical masks. Measuring barrier efficiency compared to 4 masks Yesterday afternoon, the reporter went to the Environmental Measurement and Control Optimization Research Center of the China Academy of Building Research in North Third Ring Road to test the PM2.5 barrier efficiency of four masks. The instrument used for testing was an intelligent dust monitor manufactured by TSI, USA, model number 8532. According to Li Ming, a technician, this is an internationally widely used instrument for monitoring inhalable particulate matter. It can quickly monitor inhalable particulate matter in the air with a sensitivity of 1 μg/m3. Li Ming designed a test plan for the reporter, first measuring the PM2.5 value of the room where the instrument is located, and then separately covering the metal probe of the instrument with different types of masks, simulating the situation of wearing a mask, comparing PM2.5 The change in value. The test time for each mask was set to 3 minutes, and the test results were averaged over three minutes. After the metal probe for measuring the PM2.5 value was subjected to filtration purification treatment, it was found that the indoor PM2.5 value was 400 μg/m 3 . As the monitor starts, the numbers on the dashboard are constantly changing. Li Ming said that the test results of the four masks were divided by the indoor PM2.5 value to obtain the barrier efficiencies of the four masks. Conclusion: Masks with activated carbon are the most resistant to PM2.5 After 20 minutes, the intelligent monitor automatically calculated the test results. Somewhat surprisingly, the best effect of blocking PM2.5 particles is not the N95 mask, but the KN90 mask with activated carbon filter; on the contrary, the worst barrier effect is not only a thin two-layer disposable medical mask. It is a gauze mask with a total of 24 "defense lines". The reporter noticed from the figures of real-time monitoring that the PM2.5 value measured by the simulated gauze mask experiment has been maintained at around 282, and the highest value even reached 390. That is to say, the gauze mask has almost no barrier to PM2.5 particles. It can be seen that the effect of blocking PM2.5 has nothing to do with the number of layers of gauze. In this regard, Wang Zhiyong, an engineer at the Institute of Building Materials, China Academy of Building Research explained that the 24-layer gauze mask looks much thicker than the N95 and KN90 masks, but the gap between the gauze fibers is large. Therefore, the mask is only It can filter out larger particles, and the filtration effect will be much worse for fine particles like PM2.5. He said that the key to the effectiveness of masks to block PM2.5 is the material used to make the mask. Li Ming said that he originally thought that the N95 mask should be the best barrier in the four masks, but he did not expect the filter effect of this mask to be different from the KN90 mask. “This is because the activated carbon in the mask absorbs some organic particles in the air.†According to Wang Zhiyong, according to data from the environmental protection department, more than 22% of the PM2.5 particulate sources in Beijing are from motor vehicle emissions. The exhaust contains organic matter, and activated carbon has a good adsorption effect on this organic matter, which explains why the isolation effect of the N95 mask is not as good as that of the KN90. Wang Zhiyong said that when wearing N95 and KN90 masks, the breathing will feel boring, which is because the mask has a good barrier effect. The better the barrier effect, the more laborious the breathing will be. 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