Have you chosen the right non-woven mask?

Have you chosen the right non-woven mask?

While paying attention to the government's epidemic prevention and control measures, the most important thing for the public is to protect themselves. According to experts and WHO, wearing a mask and washing hands frequently are among the most important protective measures for the public.

Why are medical staff wearing masks infected?

This is because severe pneumonia or general anesthesia requires intubation, and endotracheal intubation will produce aerosols, and aerosols are the most contagious, and can reach several times or even dozens of times the size of droplets. Coronavirus is usually transmitted by droplets. Many patients who would not infect others would become infectious through aerosols produced during intubation. This is one of the reasons why medical staff accounted for 1/3 of the total number of cases during SARS.

Therefore, medical staff working on the front line of the epidemic must wear isolation clothing.

There are many types of masks on the market, what kind of mask should I choose?

Common masks are as follows: ordinary cotton masks, disposable masks (such as: medical surgical masks, ordinary medical masks), medical protective masks (N95/KN95 masks).

Among them, medical protective masks (N95/KN95 masks) and medical surgical masks are all medical products that have obtained national standardized management after SARS in 2003, and have the function of blocking the passage of liquid and droplet particles. If worn correctly, it can effectively prevent diseases transmitted by droplets. It is our first choice for purchasing masks. They are usually made of multiple layers of non-woven fabrics.

Medical protective masks should meet the mandatory standards of China GB 19083-2010, with a filtration efficiency of ≥95% (tested using non-oily particles). It is required to pass the synthetic blood penetration test (to prevent splashing of body fluids), and it is required to meet the microbial indicators.

The N95 mask is one of the nine anti-particulate masks certified by NIOSH (National Institute for Occupational Safety and Health). "N" means non-oily particles (cooking fumes are oily particles, and droplets produced by people talking or coughing are not oily), "95" means that under the testing conditions specified by NIOSH standards, the filtration efficiency reaches 95% %. Moreover, this kind of mask has a good fit with the wearer's face, can filter particles in the air, and block pollutants such as droplets, blood, body fluids, secretions, etc., and is a commonly used personal protective equipment for airborne diseases.

N95 is not a specific product name. As long as it meets the N95 standard and has passed the NIOSH review, it can be called "N95 mask".

Microorganisms are non-oily particles. In the classification of anti-particulate masks according to NIOSH standards in the United States, category N is suitable for filtering non-oily particles. For example, the cooking fume produced by cooking is oily particles, while the droplets produced by people talking or coughing are not oily.

In China, it is the national standard KN95, which refers to the classification of non-oily particulate masks in China's national standard GB2626-2006. KN type is suitable for filtering non-oily particles, and the digital part has the same standard as the two countries, and 95 means that the filtration efficiency is ≥95%.

The filtration efficiency test methods of the above three standards are the same, so the filtration efficiency levels are consistent.

In addition, there are European standard FFP2 (oily and non-oily particle protection, with virus and bacteria protection function, filtration rate of about 94%~95%) and European standard FFP3 (oily and non-oily particle protection, with virus and bacteria protection function, filtration rate of about 99%).

Medical surgical masks are commonly used in operating rooms and other environments with body fluids and blood splash risks. They can block blood and body fluids from passing through the mask to contaminate the wearer. At the same time, the filtration efficiency of bacteria is more than 95%, but the filtration efficiency of particles is limited. And most of them are rectangular in design, and the tightness with the face is not as tight as that of medical protective masks. Common medical surgical masks include strap type, earhook type, etc.

Viruses are the smallest particle size among the particles we can come into contact with every day. PM2.5, which we are familiar with, refers to particles with a particle size of 2.5 microns or less, while the particle size of viruses ranges from 0.02 to 0.3 microns. The virus is so small, isn't it very dangerous?

This is a common misunderstanding, which is to think that the mask is a sieve, particles with a particle size smaller than the sieve can pass through, and particles with a particle size larger than the sieve are blocked outside. In fact, N95 masks are most effective in blocking large particles and the tiniest particles.

The mask is a multi-layer composite structure. The N95/KN95 mask is composed of the innermost and outermost non-woven layers, the middle electrostatic layer and the melt-blown non-woven layer. The medical surgical mask is composed of a non-woven layer and a melt-blown non-woven layer. Cloth layer. In addition to supporting the mask, the non-woven fabric layer also acts as a part of the sieve, and particles with large particle sizes will be blocked by them. Melt-blown non-woven fabric has a microfiber structure, which has good filterability and can intercept medium-sized particles. The electrostatic layer plays the role of electrostatic adsorption, and the particularly small particles are very light and will be adsorbed.

The larger the particles, the better the filtering effect, the smaller the particles, the better the adsorption effect, and the medium-sized particles are the most likely to slip through the net. According to a large number of experiments, the particle size range is between 0.2 and 0.8 microns. Therefore, in GB2626-2006 "Respiratory Protective Equipment - Self-priming Filter Type Anti-particulate Respirator", the detection of leakage requires that the particle size of the particles is between 0.02 microns and 2 microns, and the median is 0.3 and 0.6 microns.