Face mask selection
1. Masks are not suitable for people
1. People with heart or respiratory problems (such as asthma and emphysema)
3. Dizziness, difficulty breathing and sensitive skin after wearing
2. What are the characteristics of several face masks on the market?
Advantages of cotton masks: repeatable cleaning and use,
Disadvantages: Saliva will remain in the part of the mask that touches the mouth and nose. If you don’t clean it frequently, it will easily breed bacteria, which does not meet the hygiene requirements. The fibers of cotton masks are generally thick and cannot effectively filter smaller particles, and most of them have not passed the international safety certification, and the protective effect is not guaranteed. Gauze masks are almost useless, and the air leakage on both sides of the nostrils is too large.
N95 mask: It is used to prevent the person wearing it from being infected; it is impossible to prevent the patient from transmitting the virus to others.
Surgical mask: Although it is not as effective as N95 to avoid infection, it can prevent patients from transmitting the virus to others.
3. Is the smaller the dust, the harder it is to be filtered by the mask?
We generally think that the smaller the dust, the harder it is to filter, but this is a plausible concept. In terms of filtration theory, there are five main ways to filter dust:
1) Brownian Diffusion-The smaller the particles, the stronger the effect.
2) Interception-The larger the particles, the better the effect.
3) Inertial Impaction-The larger the particles, the better the effect.
4) Gravitationl Settling The larger the particles, the better the effect.
5) Static attraction-The smaller and lighter the particles, the easier it is to be attracted.
It can be seen that the smaller the dust, the stronger the effects of 1, 5 and the greater the dust, the better the effects of 2, 3, 4 are, so the smaller the dust, the more difficult it is to filter. The most difficult-to-filter particles are simply referred to as MPPS (Most Penetrating Particleize). The size of MPPS is generally 0.3 microns (otherwise 0.6 microns). Whether it is the European standard EN149, the American standard NIOSH, and the Australian AS1716 certification standard, MPPS is used for testing. As long as you purchase a certified mask, you can protect the health of your respiratory system.
How to choose the right face mask?
There are three principles for choosing face masks:
First, the dust blocking efficiency of the mask. The level of the dust blocking efficiency of the mask is based on its blocking efficiency for fine dust, especially for respiratory dust under 5 micrometers. Because this size of dust can directly enter the alveoli, it has the greatest impact on human health. In general gauze masks, the principle of dust suppression is mechanical filtration, that is, when the dust hits the gauze, it passes through layers of barriers and blocks some large particles of dust in the sand cloth. However, some fine dust, especially dust smaller than 5 microns, will pass through the gauze mesh and enter the respiratory system. At present, there are some dust masks abroad, and the filter material is composed of fibers filled with permanent static electricity. Those respiratory dusts smaller than 5 microns are attracted by static electricity and absorbed in the filter material during the process of passing through this filter material Dust really plays a role in preventing dust.
Second, the degree of closeness between the mask and the face shape. Air flows like water, wherever resistance is small, it flows first. When the shape of the mask is not close to the face, the dangerous objects in the air will leak into the airway from the non-closed place. Then, even if you choose a mask with the best filter material. Nor can it protect your health.
Third, wear comfortably. Respiratory resistance is required to be small, light weight, hygienic wearing and easy maintenance.
Use of face masks
1. Use of general face masks
The mask must be the right size and the way it is worn must be correct for the mask to be effective. Masks sold on the market are generally divided into two types, rectangular and cup-shaped. A rectangular mask must have a structure of at least three layers of paper in order to have a protective effect. The user needs to press the wire on the mask against the bridge of the nose, and then spread the entire mask along the bridge of the nose to achieve the effectiveness. Let the child wear a rectangular surgical mask because it has no fixed shape, and if it is properly tied, it can fit the child’s face. For cup-shaped masks, make sure that the mask is sufficiently dense after it is applied to the face, so that the air will not leak out when exhaled. When wearing a cup-shaped mask, cover the mask with both hands and try to blow air. Check whether there is air leakage from the edge of the mask. If the mask is not tight, you must readjust the position before wearing it.
Second, the correct way to wear a face mask
1. Place the mask in the palm and position the metal strip at the nose towards the fingertips to allow the headband to hang naturally.
2. Put on a mask, the metal part of the nose is facing upwards, and it is close to the face.
3. Put the upper headband of the mask behind the head, then pull the lower headband over the head, place it behind the neck, and adjust to a comfortable position.
4. Put your fingertips along the metal bar of the nose bridge, from the middle to both sides, and slowly press inward until it is close to the bridge of the nose.
5. Cover the mask with both hands as much as possible and conduct positive and negative pressure tests. Positive pressure test: cover the mask with both hands and exhale vigorously. If the air overflows from the edge of the mask, that is, it is improperly worn, you must adjust the headband and the metal bridge of the nose bridge again; negative pressure test: cover the mask with both hands and exhale vigorously. The mask will sink in the center. If air enters from the edge of the mask, it will be worn improperly. The headband and the metal strip of the nose bridge must be adjusted again.
6. Function of breathing valve: In a working environment with humid heat or poor ventilation or heavy workload, using a mask with a breathing valve can help you feel more comfortable when exhaling. The working principle of the breathing valve is that the positive pressure of the exhaust gas during the exhalation blows off the valve piece to quickly remove the exhaust gas in the body, reducing the sultry feeling when using the mask, and the negative pressure during inhalation will automatically close the valve to avoid Pollutants absorbed into the external environment.
3. When to replace the face mask
1. The mask is contaminated with foreign objects such as blood stains or droplets;
2. The user feels that the breathing resistance becomes greater;
3. The mask is damaged.
4. Dust-proof filter cotton, when the mask and the user’s face are in good contact, when the user feels that the breathing resistance is very large, it means that the filter cotton has been filled with dust particles and should be replaced with a new one.
5. Anti-virus filter box, when the mask is in close contact with the user’s door, when the user smells the poison, it should be replaced with a new one.
4. Face masks should not be worn for a long time
From the point of view of human physiology, blood circulation in the nasal mucosa is very strong, and the channels in the nasal cavity are very tortuous. The nose hairs constitute a filtering “barrier”. When air is sucked into the nostrils, the airflow forms a vortex in the tortuous channel, which heats the airflow sucked into the nasal cavity. Some tests have shown that when cold air at minus 7 degrees Celsius is drawn into the lungs through the nasal cavity, the airflow has been heated to 28.8 degrees Celsius, which is very close to the temperature of the human body. If you wear a mask for a long time, the nasal mucosa will become fragile and the original physiological function of the nasal cavity will be lost, so you cannot wear a mask for a long time. Masks can only be worn in special environments, such as places with many people and no air circulation. Of course, walking in the wild, in order to resist wind and sand and cold, or activities in an environment with air pollution, you need to wear a mask, but the time should not be too long. In addition, in the flu season, go to public places where there may be a large number of pathogens, you should also wear a mask. Wearing a mask is only one of the ways to prevent respiratory infectious diseases. The most important thing is to maintain good living habits.
5. Respirator face mask cleaning
The outer layer of the mask often accumulates a lot of dust, bacteria and other dirt in the outside air, and the inner layer blocks the exhaled bacteria and saliva. Therefore, the two sides cannot be used alternately, otherwise the dirt contaminated by the outer layer will be directly attached When inhaled into the body, it becomes a source of infection. When the mask is not worn, it should be folded and placed in a clean envelope, and the side that is close to the nose and nose should be folded inwards. Do not stuff it into your pocket or hang it around your neck. If the mask is wetted by exhaled heat or saliva, its effect of blocking germs will be greatly reduced. Therefore, it is best to prepare a few more masks for replacement. You should change and wash it once a day. When washing, it should be scalded with boiling water for 5 minutes, and then gently rubbed with hands. After washing with clean water, expose to the sun. However, activated carbon filters and disposable ones do not need to be cleaned.
6. The size of the face mask
After wearing, it should cover most of the area under the mouth, nose and orbit, generally 13 cm wide and 17 cm long. If the mask is too small, germs, dust, and dirt can easily enter through the edges of the mask or the gaps on both sides of the nose, which affects the filtering effect of the mask. The filtering effect of the mask is mainly on the nose, because when the person is not talking, the mouth is generally closed, but when someone wears the mask, the nostril is exposed outside the mask in order to breathe smoothly, which loses the mask to protect the respiratory tract “Barrier” effect.
How to wear N95 face mask correctly:
1. First pull the headband loose every 2-4 cm, pass the mask headband with your hand, and the metal nose is forward.
2. Put on the mask and keep it close to the face. Put the headband on the top of the mask behind the head, then pull the headband over the head, place it behind the neck, and adjust it to a comfortable position.
3. Double fingertips along the metal bridge of the nose bridge, from the middle to both sides, slowly press inward until it is close to the nose bridge.
4. Cover the mask with both hands as much as possible and conduct positive and negative pressure tests. (Positive pressure test: cover the mask with both hands and exhale vigorously. If the air overflows from the edge of the mask, it is improperly worn, you must adjust the headband and the metal bridge of the nose bridge again; The center will sink. If air enters from the edge of the mask, it will be worn improperly, and the headband and the metal strip of the nose bridge must be adjusted again.)
Characteristics of various face masks:
1. Face mask (N95): It conforms to the N95 standard approved by the National Institute of Occupational Safety and Health (NIOSH), and the filtered particles can be as small as 0.3 microns in diameter. In the test, the particles with a diameter of 0.075 microns were blocked, and the success rate was 95%. Coronavirus pneumonia (atypical pneumonia) virus has a diameter of about 0.1 to 0.12 microns.
2. Surgical face mask: made of three layers of “non-woven”, suitable for use in the operating room environment; it can block particles with a diameter of more than 4 microns.
3. Activated carbon medical mask: The added activated carbon material, the main function is to taste odor, not anti-bacterial virus, and respiratory resistance will increase, the function of bacteria isolation is 98%.
4. Dustproof mask: Mainly dustproof and antibacterial.
5. Ordinary paper masks: useful for blocking larger particles. Viruses less than 5 microns in diameter can easily pass through and have limited bacterial isolation.