First. The definition of mask: 1. According to the filt […]
First. The definition of mask:
1. According to the filter material, protective masks are mainly divided into two categories: dust masks and gas masks.
Dust mask: It is a mask that has the ability to protect against harmful dust and aerosols. Anti-virus mask: It is a respiratory protective equipment used to protect the respiratory organs from poisons, biological warfare agents and radioactive dust.
2. According to the model specifications, it is divided into flat type and arch type.
Second. The protective principle of masks: The protective function of masks is based on three principles:
[Filtering]: The material and textile method of the mask make the gap of the mask smaller than the virus volume and filter out the virus. Cotton gauze masks of ordinary materials are mainly protective based on this principle, so their protective efficiency is relatively low. [Adsorption]: The electrostatic effect of the mask will adsorb the virus on the outer layer of the mask, such as adding an electrostatic filter layer. [Killing]: The material of the mask has a sterilization function, which directly kills viruses. This is the titanium dioxide photocatalyst.
Third. Classification of various standard masks:
NIOSH (National Institute for Occupational Safety and Health) selects the particle size range for particle filter material detection:
The calculated median diameter of NaCI aerosol is 0.075±0.020μm, and the standard error is not more than 1.86; The calculated median diameter of DOP aerosol is 0.185±0.020μm, and the standard error is not more than 1.60.
According to the filter material's consideration of various aerosol filtration characteristics and test safety, the relevant standards also adopt oily (DOP, etc.) and non-oily (NaCI) aerosols respectively.
(1) NIOSH 42CFR84 standard:
NIOSH promulgated new standards for dust-type respiratory protection on June 8, 1995. According to the filter materials, they are classified into three series: N-type mask, P-type mask and R-type mask. The features of these three series of masks are as follows:
Type N: the nature of the particles is non-oily suspended particles, which can be used repeatedly, and the use time limit is according to the manufacturer's instructions; Type P: the nature of the particles is oily and non-oily suspended particles, the filtration efficiency will not be significantly reduced for a long time; Type R: the nature of particles It is oily and non-oily suspended particles, which can be reused. The use time limit is according to the manufacturer's instructions.
Each series of masks is divided into 3 levels: 95%, 99%, 99.97% (referred to as 95, 99, 100), a total of 9 sub-types of filter materials. The inspection of high-efficiency filter materials at home and abroad mostly uses particles with a particle size of about 0.3 μm as the standard. This is because research results in many countries have confirmed that due to certain characteristics of the filter material (the filtering effect is based on the combined effect of multiple principles such as filtration and electrostatic adsorption), aerosol particles with a particle size of 0.3 μm are the most Difficult to filter, the larger the aerosol particle size is 0.3 μm or the smaller is 0.3 μm, the more its filtration (protection) efficiency will increase significantly. Therefore, a mask marked NIOSH N95 means that its filtering rate of 0.3μm germs is more than 95%.
(2) European Union EN149 standard:
FFP1: the filtration rate reaches 80% FFP2: the filtration rate reaches 94% FFP3: the filtration rate reaches 97%
(3) Australia AS1716 standard:
P1: The lowest filter effect reaches 80% P2: The lowest filter effect reaches 94% P3: The lowest filter effect reaches 99%
(4) Japan MOL verification standard:
Divided into DS1, DS2, DS3 three levels. Among them, the minimum filtering effect of DS2 masks is 99%, and the minimum filtering effect of DS3 masks is 99.9%.
(5) Chinese national standards:
China issued the latest national standard "Technical Requirements for Medical Protective Masks" (GB 19083-2010) on 2010-09-02, and "Medical Surgical Masks" (YY 0469-2011) on 2011-12-31, in 2003 Released the "Ordinary Degreasing Gauze Mask" (GB 19084-2003). Among them, the "Technical Requirements for Medical Protective Masks" stipulates that the particle filtration efficiency of mask filter materials should not be less than 95%. Such as KN95 mask, KN90 mask. Example of KN95 Mask Specification.
(6) CNS standards in Taiwan:
D1: Protection efficiency is above 80% D2: Protection efficiency is above 95% D3: Protection efficiency is above 99%
2. Various commonly used masks
The masks commonly used in various industries in the society can be divided into medical masks, industrial masks and cotton gauze masks. The specific ones are: dust masks, activated carbon dust masks, dust masks with valves, and dental masks. , Surgical masks, multi-layer cotton gauze masks, gas masks, ordinary paper masks, three-layer non-woven protective masks, special square masks, long tube masks, etc.
3, the choice of masks for various groups of people
(1) People whose masks are not applicable
Pregnant women; children; patients with upper respiratory tract infection; patients with chronic respiratory disease or asthma and other lung function impairment; patients with heart disease; people with dizziness, breathing difficulties and sensitive skin after wearing; people with obvious scars on the face that affect closeness; beards Affect the close person.
(2) Application features of several common masks:
[N95 mask]: Used to prevent the wearer from being infected, and it is impossible to prevent the patient from transmitting the virus to others. [Surgical masks]: Although they are not as effective as N95 masks in preventing infection, they can prevent patients from spreading the virus to others. The standard surgical mask is divided into three layers. The outer layer has a water blocking effect to prevent droplets from entering the mask, and the middle layer has a filtering effect, which can block more than 90% of 5μm particles. The inner layer close to the mouth and nose is used to absorb moisture. [Non-woven mask]: The electrostatically treated non-woven fabric can not only block larger dust particles, but also the electrostatic charge attached to its surface can absorb fine dust through electrostatic attraction, achieving high dust blocking efficiency. However, the thickness of the filter material is very thin, which greatly reduces the user's breathing resistance and provides a better sense of comfort. [Cotton masks]: China’s SARS prevention and control technical plan stipulates that you must wear more than 16 layers of cotton masks to prevent some viruses from attacking. However, this type of mask is thick, stuffy, low in antivirus efficiency, and its structure has poor adhesion to the face. Moreover, as determined by the Beijing Medical Device Quality Supervision and Inspection Center of the State Food and Drug Administration, the filtering effect of 16-layer common material mask is 24%, and the filtering effect of 24-layer common material mask is 36.8%.
In view of the respective characteristics of N95 masks and surgical masks, we should realize that it was wrong to think that patients with respiratory infectious diseases should wear N95 masks to prevent them from spreading the virus. The correct approach is that patients with respiratory infectious diseases should wear surgical masks to prevent viruses or bacteria from spreading to the outside world to protect the surrounding healthy people, and healthy people in close contact with them should wear N95 masks to prevent themselves from being infected.
4. Selection of protective masks for SARS and new coronavirus (2019-nCoV) prevention
According to the actual measurement data published by NIOSH on March 17, 2003, the relationship between different particle size and particle collection efficiency is drawn. The filtration performance curves of various masks show that the filtration rates of the tested masks are: N95 Masks>FFP2 masks>FFP1 masks>activated carbon medical masks>medical masks>gauze masks (the filtering performance of gauze masks is significantly lower than the previous types of masks, and the protective efficiency is extremely low).
In medicine, the infection of bacteria or viruses in the air with a particle size of less than 5 μm is called air infection; the infection of bacteria or viruses in the air with a particle size of 5 μm or more is called droplet infection.
If SARS or the new type of coronavirus (2019-nCoV) is only a droplet infection, as long as the use of surgical masks can effectively prevent virus infection. But if it is transmitted through the air, you must use N95 masks or masks of the same level to effectively prevent inadvertent infection. The medical community generally recognizes three modes of transmission for SARS: ① direct droplet infection; ② "hand-to-mouth infection" in the moist areas of the mouth, nose, and eyes when the hands are infected with the virus; ③not It is ruled out that the virus is transmitted through the air conditioning system, but it is most likely that the virus adheres to the oral and nose secretions, so the particle size is still much larger than the virus itself. The SARS virus has a particle size of 0.08-0.14μm. Whether it is transmitted through any of the above three infection routes, its particle size is much larger than the size of the virus itself. The filtering capacity of N95 masks is nearly 95%. Surgical masks can filter out about 70%. Therefore, wearing masks and frequent hand washing have become the main and effective measures to prevent coronavirus. As long as the mask is sufficient to cover the nose and mouth droplets, most of the chances of infection can be avoided. On April 19, 2003, the United States CDC made recommendations on the use of masks to prevent SARS: (1) For SARS patients and their families, only surgical masks are recommended (enough to prevent oral and nose droplets); (2) For long-term Medical staff who are in close contact with SARS patients are recommended to adopt the most stringent standard for preventing airborne infections, that is, use N95 masks.
5. Precautions for the correct use of masks:
Never wear a mask in a space where the virus may exist. Try to wear a mask before entering the indoor space (because the outdoor virus concentration is low, it is usually low enough to cause infection). Never press the mask with your hands. Including N95 masks, they can only isolate the virus on the surface of the mask. If you squeeze the mask with your hands and make the virus soak through the mask with droplets, there is still a chance of infection. Make sure that the mask fits well with the face as much as possible. The simple test method is: After putting on the mask, exhale forcefully so that air cannot leak from the edge of the mask.
6. Post-use disposal measures
Disinfect discarded masks and put them into special containers after they are simply damaged (torn or cut) to prevent criminals from recycling and selling. Among them, the masks used by people in home quarantine. For people with fever, cough, sputum, sneezing symptoms, or people who have been in contact with such people, it is recommended to use 5% 84 disinfectant for the mask in a ratio of 1:99, and then sprinkle it on the mask for treatment. Throw it into other garbage (dry garbage) bins; if there is no disinfectant, you can also use airtight bags or fresh-keeping bags to seal the mask and throw it into other garbage (dry garbage) bins. Masks used by ordinary residents should be directly put into the "other garbage (dry garbage)" collection container. Medical institutions and surrounding areas can coordinate the corresponding management departments to implement the collection of medical waste containers in accordance with the medical waste management regulations. Wash hands promptly after placing.
7. Protective measures for transportation and disposal of discarded masks
Wear rainproof overalls with long sleeves (cuffs can be closed or tight), rain caps (caps can be closed), and sufficient number (not less than 2 sets) for rotation. Wear long rubber shoes of the right size. Wear disposable latex gloves or protective gloves against chemical and biological damage (reusable), and a sufficient number (not less than 2 sets) of protective gloves should be provided for rotation. Wear disposable surgical masks (at least two layers) or N95 masks. Disposable masks need to be replaced every 4 hours at most, or when they are soaked and lose their protective effect. Wear suitable size protective glasses (medical protective glasses or chemical protective goggles). Special changing places or locker rooms can be set up, so that reusable work clothes, rubber shoes, protective gloves, protective glasses and other items can be cleaned and disinfected collectively. For cleaning and disinfection of labor protection protective equipment, chlorine-containing disinfectant (such as 84 disinfectant), peracetic acid disinfectant, etc. can be used, and use according to the instructions. Equipped with hand sanitizer, wash hands frequently, thoroughly, and clean, and pay attention to personal hygiene. After the disposable protective equipment is used, it is discarded in the garbage truck and transported to the garbage incineration plant for disposal. After the operation is completed, the garbage collection container, collection and transportation vehicle and loading tools are washed and killed.