N95 face-mask

N95 face-mask

N95 face-mask is one of nine particle respirators certified by NIOSH (National Institute for Occupational Safety and Health). N95 is not a specific product name. As long as the product meets the N95 standard and gets approval of NIOSH, it can be called N95 face-mask. The filter efficiency of N95 face-mask can reach over 95% for particles with aerodynamic diameter of 0.075 µ m ± 0.020 µ m.

Foreign name: N95 face-mask

Certification authority: NIOSH

Category: Respirator

Classification: Cup cover, folding

Function: Its filter efficiency can reach over 95% for particles with aerodynamic diameter of 0.075 µ m ± 0.020 µ m

Introduction of N95 face-mask

N95 face-mask is one of nine particle respirators certified by NIOSH. “N” means “not resistant to oil”. “95” means that when the mask is exposed to a specified number of special test particles, the particle concentration inside the mask is over 95% lower than that outside the mask. 95% is not an average, but a minimum. N95 is not a specific product name. As long as the product meets the N95 standard and gets approval of NIOSH, it can be called “N95 face-mask”. The protection level of N95 indicates that under the testing conditions of NIOSH standard, the filter efficiency of mask filter material to non-oily particles (e.g. dust, acid mist, paint mist, microorganism) reaches 95%.

Function and use

The filter efficiency of N95 face-mask is over 95% for particles with aerodynamic diameter of 0.075µm±0.02µm. The aerodynamic diameter of aerobacteria and fungal spores varies between 0.7-10µm and is within the protection range of N95 face-mask. Thus, N95 face-mask can be used as a respiratory protection product to filter some particulate matters, such as dust generated during grinding, cleaning, processing minerals, flour and some other materials, and is suitable for preventing liquid due to spraying, or non-oily particles that do not generate harmful volatile gases. N95 face-mask effectively filters and purifies the inhalation of unusual smells (except toxic gases) and helps reduce exposure to certain inhalable microbial particles (e.g. mold, anthrax, tuberculosis), but it can not eliminate the risk of contact infection, illness or death.

The US Department of Labor recommended that medical staff wear N95 face-masks to prevent microbial airborne diseases such as influenza and tuberculosis.

Common types

According to the shape, masks are usually divided into cup cover type and folding type.

Safety standard

Other NIOSH-certified particle respirator levels include: N95, N99, N100, R95, R99, R100, P95, P99, P100, a total of 9 types. All these protection levels can cover the protection range of N95.

“N” means “not resistant to oil” and is suitable for non-oily particles.

“R” means “resistant to oil” and is suitable for oily or non-oily particles. If used for the prevention of oily particles, the particle respirator shall not be used for more than 8 hours.

“P” means “oil proof” and is suitable for oily or non-oily particles. If used for the prevention of oily particles, the particle respirator should be worn according to the manufacturer’s recommendations.

“95”, “99” and “100” levels refer to the filter efficiency when tested with 0.3 micron particles. “95” means that the filter efficiency is above 95%, 99 means that the filter efficiency is above 99%, and 100 means that the filter efficiency is above 99.7%.

Suitability test

In addition to the filter efficiency of N95 face-mask, the tightness between mask and face is one of the important factors that determine the effectiveness of mask. There are great differences in the suitability between different types of masks and faces. Therefore, before wearing a mask, the suitability of the mask should be tested first. When doing the wearer’s cheek tightness test, make sure that air passes through the mask when the mask is tightly attached to the face edge.

Dustproof and medical

Cao Xuejun, deputy director of the Consumer Goods Industry Department of the Ministry of Industry and Information Technology, said at a press conference on the 2nd that N95 face-masks refer to those with a filter efficiency of 95%, which are divided into industrial dust-proof and medical masks, and medical N95 face-masks are more protective.

Step Close to N95 Mask Production Line reported: “Workers pack medical protective N95 masks (taken on February 8). In recent days, Shenyang Shengshi Medical Technology Co., Ltd., the only medical protective N95 mask manufacturer in Liaoning Province, had continuously produced masks more than 20 hours a day to ensure the daily output of over 20,000 masks to supply the front-line epidemic prevention in Hubei Province and Liaoning Province.”


  1. Wash your hands before wearing a mask. During wearing a mask, please be careful not to touch the inside of the mask, which will reduce the possibility of contamination of the mask.
  2. Distinguish the inside, outside, up and down of a mask.
  3. Don’t squeeze the mask with your hands. N95 mask can only isolate the virus on the surface of the mask. If you squeeze the mask with your hands, the virus will soak the mask along with the droplets and easily cause virus infection.
  4. Try to fit the mask well on your face. The simple test is that after wearing a mask, exhale forcefully. If air cannot leak from the edge of the mask, the mask is proved to fit the face well.
  5. The protective mask must be tightly attached to the user’s face, and the user must shave off his beard to ensure that the mask can be close to the face. Beards, and anything between the mask gasket and the face can cause the mask to leak.
  6. After adjusting the mask, press the nose clip along the upper edge of the mask with the forefinger of both hands so that it is close to the face.

Replace the mask in time when:

1. Respiratory impedance increased obviously;

2. A mask is damaged;

3. A mask and face cannot be tightly attached.

4. A mask is contaminated (such as stained with blood or droplets and other foreign bodies);

5. A mask has been contaminated (used in individual wards or or in contact with patients);

5. A mask is one containing activated carbon and the mask has peculiar smell;

6. The use time of mask exceeds the recommended duration.

Performance limitation

1. Respiratory infectious diseases are not only transmitted through respiratory tract;

2. The preventive measures should be taken before the exposure of novel coronavirus.

3. The tight-fitting structure and high-efficiency filtration of the mask will increase respiratory resistance and reduce comfort.

4. If the mask does not apply to the user’s face, it will affect the suitability and cause leakage.

5. The protective mask can effectively reduce the concentration of harmful substances by 90% when it is suitable and used correctly.

6. The government has not established a safe exposure limit for pathogenic microorganisms. Respiratory protection can only reduce the risk of disease, but cannot eliminate the risk.

Selection of masks

  1. Select a suitable mask

A medical mask should be the first choice for medical workers, and an ordinary absorbent gauze mask should be the first choice for ordinary citizens. In special occasions, such as seeing a doctor and visiting patients, ordinary citizens had better  wear a medical mask.

  • Select a qualified mask

When selecting a mask, it is necessary to see whether the trade name is printed on the outer package, whether there is information about the manufacturer or supplier, whether there is a certificate of approval or instructions for use. A disposable mask must be marked with a disposable label and a method of sterilization must be indicated for a reusable medical mask. Generally speaking, an ordinary gauze mask should be marked as ordinary or sterile. The mask materials should be odorless and harmless to health, especially the materials contacting our face should be non-irritating and non-allergic.

  • Check the appearance of a mask

It is easy to ignore this when selecting a mask. We should check whether the packaging of mask is complete and damaged. There shall be no holes or stains on the surface of mask. A medical mask shall not have exhalation valves. The transverse diameter of the closed arch mask shall not be less than 14cm, and its longitudinal diameter shall not be less than 14 cm. The length and width of the medical rectangular mask shall not be less than 17cm. The length of an ordinary absorbent gauze mask after being unfolded shall not be less than 17cm, the width shall not be less than 13cm, and the number of layers shall not be less than 12. In addition, it must be noted that if a medical mask is selected, it must be provided with a nose clip, which is made of bendable plastic material and is not less than 8.5cm in length.

Expert advice

The N95 mask, which is sold well online, has a filtering effect of 95% after testing. But for the N95 mask, the doctor reminded the public that “theoretically, the more airtight the mask’s protective material, the better the effect of blocking particles.” However, the more airtight the mask is, the more difficult it is for the wearer to breathe. For patients with cardiovascular diseases, if they do not wear a mask properly, they may suffer from dizziness and dyspnea due to lack of oxygen. Wearing a mask should be prudent.”

N95 face-mask

Leave a Reply

Your email address will not be published. Required fields are marked *

Scroll to top