How to choose sugical medical masks and KN95 masks in China

 China produces 50 percent of the world's masks. There are six types of masks KN95 alone. Choosing the right mask is not the most expensive or cheapest. This is a good article to teach us how to choose masks.

Several large-scale infectious diseases in recent years, such as SARS, MERS, H7N9, and the recent new coronavirus in Wuhan, are all infectious diseases mainly based on the respiratory tract and mucous membranes. In addition to frequent hand washing and disinfection, precautions must be taken when entering and exiting public places. Wear a mask to prevent droplet transmission. There are many types of masks on the market, which one is anti-virus, which one is not, and what is N95? Is it necessary to stock N95?

1. Which mask can prevent viruses?

The masks available on the market are:

Thermal cotton mask

Starproof paparazzi mask

Activated carbon mask

Disposable medical mask

Medical-surgical mask

N95 mask

N95 medical protective mask

The first three types of masks are not anti-virus. The only ones that can prevent viruses are disposable medical masks, medical-surgical masks, N95 masks, and N95 medical protective masks.

Academician Zhong Nanshan’s suggestion is that you don’t have to wear N95, because these viruses are not, in fact, separate, they often exist in droplets. Ordinary masks, surgical masks, etc. can still prevent most of them from carrying droplets. The virus enters the respiratory tract. If you are going to the general open-air public place and do not contact the patient, you can choose to wear medical surgical masks without over-protection, but if you will contact patients with suspected respiratory infections, wear N95 masks.

2. What is a medical-surgical mask

The medical mask has a three-layer structure. The outer layer blocks liquids, the middle layer blocks germs, the inner layer absorbs moisture, and the nose is fixed with aluminum strips. Only one layer cannot be called a medical mask, and it has no protective effect. Whether it is a blue, green or pink medical mask, the dark side is the outer layer and the light or white side is the inner layer. Do not wear it upside down.

In the United States, medical masks are classified into three levels: ASTM Level 1, ASTM Level 2, and ASTM Level 3. The higher the level, the better the protection. Level 1 and level 2 masks are often called procedure masks; Level 3 masks can be used in the operating room, also called surgical masks. For daily protection in public places, Level 1 masks are actually sufficient, and its filtration efficiency against bacteria has reached 95%. The greater your exposure to the virus, the higher the level of protection you choose

ASTM refers to the American Society of Testing and Materials, which sets the following standards for medical masks:

BFE (Bacterial Filtration Efficiency): BFE is used to measure the ability of medical masks to filter out bacteria when attacked by bacteria-containing aerosols. ASTM uses 3.0-micron droplets containing Staphylococcus aureus for testing. The average size of Staphylococcus aureus is 0.6-0.8 microns. Medical/surgical masks require a minimum 95% filtration rate (level 1), and moderate (level 2) and highly protective masks (level 3) must have a bacterial filtration rate greater than 98%. PDF (Particulate Filtering Efficiency): PFE is used to measure the filtering effect of medical masks on sub-micron particles to simulate the filtering effect of viruses. The higher the filtration percentage, the better the filtering effect of the mask. It is generally possible to use 0.1 to 5.0-micron particles for testing, but the ASTM F2100-11 standard specifies the use of 0.1-micron particles. Level 1 medical masks have a minimum PFE of 95% and Level 2 and Level 3 have a minimum of 98%.

Fluid Resistance: Fluid resistance reflects the ability of medical masks to block fluids. ASTM requires testing with synthetic blood at pressures of 80, 120, or 160 mm Hg to meet low, medium, or high fluid resistance requirements. These pressures are related to blood pressure, 80 mm Hg = venous pressure (Grade 1), 120 mm Hg = arterial pressure (Grade 2), and 160 mm Hg = arterial pressure (Grade 3).

Delta P (pressure difference): Delta P measures the airflow resistance of medical masks and is an objective measure of breathability. Delta P is measured in mm H2O / cm2. The lower the value, the more breathable the mask feels. ASTM standards require that Delta P be less than 5.0 for moderate and high protective masks and Delta P be less than 4.0 for low-grade medical masks.

Open flame tolerance: Oxygen and other flame-producing medical tools are used in hospitals. The ASTM F2100-11 standard includes flame resistance testing. Testing requires that all medical masks be able to withstand exposure to a burning flame (within a specified distance) for three seconds

Key points: the dark side facing outwards, the light side facing inwards; side with nose clips facing up, wrinkles down; adjust nose clips to fit the face; change once every 4 hours

3. What is N95 mask

According to the NIOSH air filtration rating standard, the letters “N”, “R”, and “P” indicate resistance to oily particles. “N” does not apply to oily particles. “R” has a certain resistance, and “P” is For strong resistance to oily particles. Subsequent numbers are the percentage of particles that can be filtered, 95 will block 95% of the particles. Therefore, the N95 mask is a mask that can block 95% of non-oily particles (including PM2.5) with a diameter of 0.3 microns and above. Similarly, there are N99 and N100, which means that the blocking rate is 99% and 100%.

N95 masks are more protective than medical masks. Because the medical mask does not cover the nose and mouth in all directions, there is still a large gap at the edge of the mask. N95 masks cover the nose and mouth in all directions without leaving gaps and have better protection for people exposed to germ environments. However, the N95 mask will cause the wearer to breathe uneasily and cannot be worn for a long time. Therefore, it is recommended to wear only those with severe haze or medical personnel exposed to the germ environment. If you wear N95 and breathe freely, you can only say that you are wearing it incorrectly

Key points: the convex side facing outwards, nose clip side facing. Attach the lower strap first and then the upper strap. Squeeze the nose clip to fit your face. No air leakage when blowing or inhaling

4, N95 mask identification

We are most familiar with 3M brand masks. But not all 3M masks are N95 masks, and not only 3M brand N95 masks.

N95 masks from regular manufacturers, each mask should have the following identification:

NIOSH approved manufacturer name or registered trademark.

Uppercase NIOSH letter or Logo.

NIOSH test and certification approval number, such as TC-84A-XXXX.

NIOSH filter series and filter efficiency grades such as N95, N99, N100, R95, P95, P99, P100.

Mask model, such as 9010, 1860.

Precautions for attaching a mask:

1. When used for the protection of oily particulate matter, the cumulative use time of Class R is not more than 8 hours; the cumulative use time of Class P is not more than 40 hours, or the cumulative use time reaches 30 days from the beginning, whichever comes early.

2. Protective masks cannot be washed, because washing will damage the filter material and mask structure of the mask; when it is not contaminated and damaged, and it meets the hygienic requirements, it can be considered to be used again.

3. N95 masks are not product trademarks or brands. N95 is the lowest requirement of American NIOSH (National Occupational Safety and Health Research Institute) for the filtration efficiency level of American occupational anti-particulate respirator. The filtration efficiency of particulate matter (such as dust, paint mist, acid mist, microorganisms, etc.) is at least 95%.

4. The higher the filtering efficiency of the mask, the greater the resistance to breathing. Therefore, wearing an N95 mask for a long time is not good for the body, do not wear it for a long time.

5. With regard to the frequency of mask replacement, there is no clear conclusion at present, and there are no relevant regulations on the use time of masks in China. Some researchers have done research on the protection efficiency and wearing time of KN95 medical protective masks. The results show that the filtration efficiency of KN95 masks is still above 95% after 2 days of wear, and the respiratory resistance does not change much. The filtration efficiency is reduced to 94.7 after 3 days of wearing %.

China is a country with a very complete industrial system. As the world’s largest mask manufacturer and exporter, China’s annual output accounts for about 50% of the world’s total. As an injection mold supplier in Shanghai, China, we specialize in the production of injection molds, injection processing, and medical product parts.

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