N95, kn95, N90, medical surgical masks. Are you right about these masks?
If you ask what is the biggest shortage in 2020? You must say it's a mask! Yes, since the novel coronavirus pneumonia outbreak, it is simply "hard to get".
From February 2, Shanghai launched the supply mode of "appointment registration of village committee + purchase of designated Drugstore". Before that, Xiamen, Hangzhou, Guangzhou, Nanjing and other places also implemented measures such as booking registration to buy masks. For example, Xiamen carried out online lottery to buy masks, and Hangzhou decided to uniformly deliver the masks successfully reserved by citizens to their homes. In Beijing, you can only take the chance to line up for three hours in front of some drugstores selling masks, and then buy three masks! It's just too hard. But would you choose a mask? Have you been wasting the masks you snatched?
During the novel coronavirus infection novel coronavirus infection, the guidelines for the prevention of new coronavirus infection were developed by experts from the national health and Health Commission to guide the scientific and rational selection and use of masks by different populations.
In this guide, masks are divided into four categories: disposable medical masks, medical surgical masks, kn95 / N95 and above particulate protective masks, and medical protective masks. The guide reminds that novel coronavirus is an important defense line for preventing respiratory infectious diseases, and can reduce the risk of new coronavirus infection. The mask can not only prevent the patient from spraying droplets, reduce the amount and speed of the droplets, but also block the droplets containing virus and prevent the wearer from inhaling.
But do you really know about masks? What kinds of masks are there? What's the difference?
What's the difference between N95 and kn95?
In China, affected by the epidemic, "N95 / kn95 mask" has become a hot commodity. However, most of the public do not know what is "N95 / kn95 mask", "N95" and "kn95" are different.
Kn95 respirator is mainly classified according to the national standard gb2626-2006 respiratory protective equipment self suction filter type particulate matter respirator. According to the efficiency level of filter elements, masks are divided into kn and KP categories. Kn is suitable for preventing non oil particles, such as all kinds of dust, smoke and microorganism. KP is suitable for preventing non oil and oil particles. Typical oil particles, such as oil smoke, oil mist, asphalt smoke, particles contained in diesel engine exhaust and coke oven smoke, etc.
According to the filtering effect, three levels are divided: 95%, 99%, 99.97% (referred to as 95, 99100). The common oil resistant particle masks are divided into three grades: kp100, kp95 and kp90. Dust masks are divided into kn100, kn95 and Kn90. Among them, kn95 respirator should have a filtration efficiency greater than or equal to 95% when tested with sodium chloride particles.
N95 respirator is one of nine kinds of particle respirators certified by NIOSH (National Institute of occupational safety and health). "N" means not resistant to oil. "95" means that the filter efficiency of mask material shall be ≥ 95% when exposed to special test particles with specified concentration and particle size distribution.
In fact, the filtering effect of the mask is mainly determined by the filter material in the mask. The filter material commonly used for mask is melt blown cloth, and the main raw material is microfiber formed by polypropylene. This material is characterized by good air filtration, low resistance, high efficiency and high dust capacity.
Generally speaking, the higher the protective performance of the mask, the greater the impact on the comfort performance. When people wear masks to inhale, they have some resistance to air flow. When inspiratory resistance is too large, some people will feel dizzy, chest tightness and other discomfort. Therefore, the basic principle of wearing masks is scientific and reasonable wearing, standardized use and effective protection.
Can PM2.5 mask prevent virus infection?
In recent years, the public is more and more worried about air pollution (such as the concentration of PM2.5 exceeds the standard), and the outbreak or epidemic of respiratory infectious diseases caused by new emerging pathogenic viruses also occur from time to time. Many people will spontaneously choose to wear masks to protect themselves when they go out, so that particle masks have a more extensive application.
Particle respirator is one of the main categories of professional respirators. It is designed to protect dust, smoke, smoke and other particulate air pollutants, and provide respiratory protection for the wearer. At present, the particle respirators produced in China shall comply with the requirements of GB 2626-2006 self-priming filter respirator for respiratory protective equipment and GB / T 32610-2016 technical specifications for daily protective respirators.
Among them, GB / T 32610-2016 technical specification for daily protective masks is the first national standard for civil protective masks, which was officially implemented on November 1, 2016. Before the new national standard came into effect, there was no standard for protective masks for ordinary people. Many masks use "filter efficiency" to express their anti haze performance, and often call themselves "filter efficiency is more than 90%".
In fact, "filter efficiency" does not fully reflect the protection ability of the mask. Even if the filtering effect of the filter element can reach 99%, if the sealing of the contact part between the mask and the face is not good, its protection ability will be greatly reduced. Therefore, the new national standard uses the comprehensive index of "protective effect" to define the performance of the mask, which is the intuitive effect of "air quality inhaled into the body after wearing the mask".
Can PM2.5 mask prevent virus infection? PM2.5 refers to particles with a diameter of 2.5 microns or smaller. Different haze masks should be analyzed in detail.
For example, our commonly used 3m9001 and 3m9002 foldable valved particle respirators meet the standard of G