What does KN95, N95 mean? How long can I wear a mask? Is the higher level of protection better

- Apr 03, 2020-

一. How to choose a mask?

916711a5-6c40-41a0-b1d6-9bae5331815a

At present, China's medical masks are mainly divided into three types: medical protective masks with the highest protection level, medical surgical masks commonly used in invasive operating environments such as operating rooms, and ordinary disposable medical masks.

Medical protective masks: Meet the standards of GB19083-2010 "Technical Requirements for Medical Protective Masks", which can prevent airborne diameter ≤5μm infection factors or close-range (<1m) contact with droplet-borne diseases to cause infection. Important technical indicators include non-oily particle filtration efficiency and airflow resistance:

1. Filtration efficiency: Under the condition of air flow rate of 85L / min, the filtering efficiency of the mask for non-oily particles is shown in the following table 1.

2. Inspiratory resistance: Under the above flow conditions, the inspiratory resistance does not exceed 343.2Pa (35mmH2O).

Medical surgical masks: Comply with YY0469-2011 "Technical Requirements for Medical Surgical Masks", made of non-woven fabric or composite material, the three layers are: outer layer waterproof, middle layer filter adsorption, inner layer moisture absorption, can filter contact diameter> 5μm Infectious agents can prevent blood, body fluids and splashes from providing a physical barrier, and masks worn by medical staff during invasive procedures. Important technical indicators include filtration efficiency, bacterial filtration efficiency, and respiratory resistance:

  1. Filtration efficiency: The filtration efficiency of non-oily particles is not less than 30%;

  2. Bacterial filtration efficiency: The bacterial filtration efficiency is not less than 95%;

Medical protective masks: Meet the standards of GB19083-2010 "Technical Requirements for Medical Protective Masks", which can prevent airborne diameter ≤5μm infection factors or close-range (<1m) contact with droplet-borne diseases to cause infection. Important technical indicators include non-oily particle filtration efficiency and airflow resistance:

1. Filtration efficiency: Under the condition of air flow rate of 85L / min, the filtering efficiency of the mask on non-oily particles is shown in the following table.



Filtration efficiency chart


2. Inspiratory resistance: Under the above flow conditions, the inspiratory resistance does not exceed 343.2Pa (35mmH2O).

Ordinary medical masks: Comply with YY / T0969-2013, and generally lack the filtration efficiency requirements for particles and bacteria, or the filtration efficiency requirements for particles and bacteria are lower than medical surgical masks and medical protective masks. Suitable for general protection of medical and related personnel.



95N95 mask: Effectively filter non-oily particles with high-efficiency electrostatic filter cotton and melt-blown non-woven material, and the filtration rate is greater than 95%. Used to provide respiratory protection. The N95 mask is one of nine anti-particulate masks certified by the National Institute of Occupational Safety and Health. "N" refers to particles that are not suitable for oily; "95" refers to a filtration efficiency of 95%. The N99 mask has a filtration efficiency of 99%. The N95 mask has a filtration rate of> 95% for bacteria in the air of 0.3 μm.

二. The use of masks

      The Beijing Medical Device Inspection Institute recommends that medical surgical masks and medical protective masks can block the pollution caused by blood and body fluid splashing. It is necessary to block the pollution of airborne particles and pathogenic microorganisms. Please choose to wear medical protective masks. To prevent new pneumonia, experts recommend that the public wear it-medical surgical masks or N95 masks! Among them, medical surgical masks are generally sold in pharmacies, and N95 masks are currently only available at certain specialty drug stores or medical device companies. For ordinary citizens, if they go to public places and do not come in contact with patients, it is sufficient to wear medical surgical masks without over-protection. If the patient is in contact, wear a bio-resistant N95 mask. The commonly used N95 masks are actually divided into two types, one is a bio-proof mask (blue-green), model 1860 or 9132; one is a dust-proof mask (white), model 8210.

Recommended index: N95 masks = Medical protective masks > Medical surgical masks > General medical masks

      Rejecting the "three no" masks

      note:

1. N95 is divided into two types with or without exhalation valve. For people with chronic respiratory disease, heart disease, or other conditions with dyspnea, using the N95 respirator may make it harder for the wearer to breathe, so using an N95 mask with an exhalation valve makes it easier to breathe Some and help reduce heat buildup. The presence or absence of an exhalation valve does not affect the respiratory protection of the wearer. Simply put, the N95 with exhalation valve protects the wearer, but not the people around it. If you are a virus carrier, please choose N95 without exhalation valve, and don't spread the virus.

      2. When choosing a mask, do not blindly choose a mask with a high protection level. The higher the protection level, the greater the breathing resistance of the mask, the poorer the experience when wearing, and the comfort will decrease. It has a certain resistance to air flow. When the inhalation resistance is too large, people will feel dizziness, chest tightness and other discomforts. With different physical differences, the feeling of comfort will also be different. Generally, you can choose N95 mask.

      3. KN95 is one of the levels specified in the Chinese standard GB2626-2006, and N95 is one of the levels specified in the US standard 42 CFR 84. The technical requirements and test methods of these two levels are basically the same, and the filtration efficiency reaches 95% under the corresponding standards, so there is no difference in the use effect of KN95 and N95.

三 、 How to wear a mask correctly?

1. Wash hands before wearing a mask, or avoid touching the inside face of the mask during wearing the mask to reduce the possibility of contamination of the mask.

2. Clearly distinguish the inside and outside of the mask, the top and bottom, the light-colored surface is inside, should be close to the mouth and nose, and the dark-colored side is facing outward;

3. Never squeeze the masks by hand, including N95 masks, you can only isolate the virus on the surface of the mask. If you squeeze the masks with your hands, the virus will wet the mask with the droplets, there is still a chance to infect the virus.

4. Be sure to make the mask fit the face as much as possible. The simple test method is: after putting on the mask, exhale hard, and air cannot leak out from the edge of the mask.

Correctly wear medical protective masks / N95 masks, followed by medical surgical masks, wash your hands before wearing a mask, and wear a mask when you go out. No matter what type of mask, the time limit for use is limited, it must be replaced regularly, preferably not 2 Replace every 4 hours. The mask is wet or soiled by secretions, and its protective performance is reduced. It is recommended to replace it immediately. Studies have shown that the N95 mask is worn for 2 days, the filtering efficiency remains above 95%, and the respiratory resistance does not change much; the filtering efficiency is reduced to 94.7% after 3 days of wearing.

四. How to deal with used masks?

★ For ordinary people, the risk is low, you can throw the used mask directly into the trash can, and then wash your hands with running water in time.

★ For people who are suspected of having infectious diseases, they should give the used masks to the corresponding staff when treating or under investigation and treatment, and treat them as medical waste.

★ For people who have fever, cough, sputum, sneezing or other people who have contacted this kind of people, it is recommended to throw the mask to the trash bin first, and then use 5% 84 disinfectant solution according to the ratio of 1:99 , Skim to the mask for processing. If there is no disinfectant, you can also use a sealed bag or fresh-keeping bag to seal the mask and throw it into the trash can.

    At present, from the recent characteristics of the new type of coronavirus, it is mainly transmitted through the respiratory tract. You must wear a mask when you go out. You do not have to blindly pursue medical surgery or N95 protective masks. For ordinary people with low risk of contact with patients, the effect of wearing disposable medical mask Better than not wearing it. For workers who need to commute to and from work, wearing disposable medical surgical masks and N95 / KN95 masks, washing hands frequently, avoiding crowded areas and high-risk areas can prevent new types of coronavirus pneumonia to a great extent.