According to the protection level of medical masks to the wearer, medical masks can be divided into four levels:
Minimum respirators are suitable for short procedures or inspections that do not involve liquids, mist spray or aerosols.
usually with earrings, are the general standard for surgical and procedural applications, with a fluid resistance of 80 mmHg. They are suitable for low-risk environments without liquids, mist spray or aerosols.
The two-level mask has a fluid resistance of 120 mm Hg, providing a barrier to prevent mild or moderate aerosols, liquids and spray.
The three-level respirator is suitable for a large exposure to aerosols, liquids and spray. It is resistant to 160 mmHg of liquid.
It should be noted that medical masks and surgical masks are different. Masks are designed to keep out splashes or aerosols (such as the moisture from sneezing), which are loose on the face. The function of respirator is to filter the virus and bacteria in the air and form a seal around the mouth and nose. Their ratings include N95, n99, and N100, depending on the percentage of particles they should filter out (in N100 respirators, 99.97% of particles are blocked by masks). Legal surgical respirators are approved by FDA and NIOSH (National Institute of occupational safety and health). Respirators should be used when the patient has virus infection or particles, steam or gas.
Surgical masks are not the same as surgical masks. Procedural masks are used in hospital clean environment, including ICU and obstetric ward, but they are not suitable for the sterile environment such as the operating room.