Types and Classifications
1- Disposable Protective Masks
This is the mask that looks exactly the same as a surgical/medical mask. It is categorized under the Chinese standard GB/T 32610-2016 and it is not very clear in which Europe nor US standards this is included.
GB/T 32610 is a "non-medical" face mask and basically used for civilians and not for doctors, nurses or other medical personal that come in contact with patients that could have been infected with a virus. The mask is used when the air quality is not optimal. The mask is graded based on its Filtration Effectiveness as Level A, B, C and D, all ranked to their protective effect percentage.
- Level A mask is for serious pollution
- Level B mask is for severe and below pollution
- Level C mask is for heavy pollution and below
- Level D mask is for moderate and below pollution
The disposable protective mask is the cheapest of all masks as it is for civilian use, only Level A or B masks are recommended to be used at epidemic time.
There are also 2-layer masks in the market that are cheaper but their filtration rate is not high so it is not very effective compared with other masks. Always perform tests or check the test reports.
2- Disposable Medical Masks
This 3-layer mask must comply with the standard YY/T0969 (China) or EN 14683 (Europe) and is a single-use medical mask, mostly in blue on the outside and white on the inside. It is suitable to use in public places that are not crowded, in an ordinary medical environment for cleaning personal or patients. The filtration efficiency for particles and bacteria are lower than medical-surgical masks and medical protective masks that are used for general protection of medical personnel like doctors and nurses.
3- Surgical Masks
These are the flat ones with a blue, white, green or pink colour on the outside and a white colour on the inside. The colour itself is not of importance but the material that is being used is. Surgical masks follow the YY 0469 standard (China) or EN 14683 (Europe). There are different performance requirements and specification developed by the American Society of Testing and Materials (ASTM) which is indicated with 5 basic criteria:
- BFE (bacterial filtration efficiency) measures how well the mask filters out bacteria when challenged with a bacteria-containing aerosol. ASTM specifies testing with a droplet size of 3.0 microns containing Staph. aureus (average size 0.6-0.8 microns). In order to be called a medical/surgical mask, a minimum 95% filtration rate is required. Moderate and high protection masks have bacterial filtration rates of 98% to greater than 99%.
- PFE (particulate filtration efficiency) measures how well a mask filters sub-micron particles with the expectation that viruses will be filtered in a similar manner. The higher the percentage, the better the mask efficiency. Although testing is available using a particle size from 0.1 to 5.0 microns, ASTM F2100-07 specifies that a particle size of 0.1 micron be used. When comparing test results it is important to note the size of the test particles used, as use of a larger particle size will produce a misleading PFE rating.
- Fluid Resistance reflects the mask's ability to minimize the amount of fluid that could transfer from the outer layers through to the inner layer as the result of a splash or spray. ASTM specifies testing with synthetic blood at pressures of 80, 120, or 160 mm Hg to qualify for low, medium, or high fluid resistance. These pressures correlate to blood pressure: 80 mm Hg = venous pressure, 120 mm Hg = arterial pressure, and 160 mm Hg correlates to potential high pressures that may occur during trauma, or surgeries that include high pressure irrigation such as orthopaedic procedures.
- Delta P (pressure differential) measures the air flow resistance of the mask and is an objective measure of breathability. A controlled flow of air is driven through a mask and the pressure on either side of the mask is determined. The difference in pressure is measured and divided by the surface area (cm2) of the mask segment tested. The higher the Delta P value, the harder it is for the wearer to breathe. The Delta P is measured in units of mm H2O/cm2. The ASTM standard requires that masks have a Delta P of less than 5.0, as a higher value would be considered too "hot" for general medical or surgical use. Masks with a Delta P of less than 4.0 are considered acceptable, while masks with a Delta P less than 2.0 would be considered "cool".
- Flammability: Operating rooms contain sources of oxygen and other gases used for anaesthesia, and there are potential fire hazards from electrosurgical procedures such as lasers or cautery equipment. All products used within the operating room, including face masks, are tested for flame resistance. As part of ASTM F2100 testing, masks must withstand exposure to a burning flame (within a specified distance) for three seconds.
4- Respirator masks
A) N95 masks
There are several names mentioned like N95 and KN95 when it comes to respirator masks. But what do they mean? N95 is not a specific product name but refers to a certain American standard called NIOSH (National Institute of Occupational Safety and Health).
The "N" refers to oil-resistant particles (not resistant to oil, the oil fume produced by cooking is oily particles, and the droplets produced by people speaking or coughing are not oily).
The "95" refers to the NIOSH standard of the detection condition which should have a filtration efficiency of 95% or higher. So an N95 mask is not a product name as many would think. When the product reach the N95 standard under NIOSH only then it can be called a N95 mask.
The US NIOSH 42CFR-84 standard has the highest recognition in the world.
There are 3 different filter materials classifications that ranks the percentage of the filtering efficiency of the middle layer of the mask.
Respirators are rated "N", "R" or "P":
- "N" if they are Not resistant to oil. For example, the oil fume produced by cooking is oily particulate matter, and the droplets produced by people when speaking or coughing are not oily.
- "R" if somewhat Resistant to oil. This can protect non-oily and oily suspended particles. When it is used for oily particles then the usable time should not exceed 8 hours.
- "P" if strongly resistant to oil (oil Proof). Compared with the R series, the P series is used for a relatively long time.
- B) KN95 masks
KN is the Chinese standard that is similar to the N (NIOSH) standard of the United States. It is classified under the GB2626-206 standard and can be divided under KN or KP masks. The numbers behind the "N" or "P" represent the protection level of the mask and the larger the number the better the filter efficiency is.
"KN" refers to oil-resistant particles (not resistant to oil, the oil fume produced by cooking is oily particles, and the droplets produced by people speaking or coughing are not oily). This is same as with the "N" of the NIOSH standard.
"KP" refers to strongly resistant to oil (oil Proof). So it is suitable for preventing non-oily particles and oily particles for a relatively long time.
- C) FFP Masks
"FFP" or Filtering Facepiece Particles is the European equivalent of the N95 and KN95 mask. It is a half-face mask that protects the chin, nose and mouth. The filtration rate, as well as the degree of leakages around the edges must meet certain standards and effectiveness tests. It protects the wearer from inhaling infectious agents or pollutants in the form of aerosols, droplets, or small solid particles. To ensure to have the highest protection it is important to use the mask in a correct way when adjusting it to the face.
- FFP1: The filtration is minimum 80% and is mainly used as a dust mask to filter dust (coal, zinc, aluminium, cement and other) that can cause lung diseases. The mask is marked with yellow elastic bands.
- FFP2: The filtration is not less than 94% and is used is various areas of the industry as it effectively stops powdered chemicals. It also protects against influenza viruses such as avian influenza or severe acute respiratory syndrome associated with the coronavirus (SARS), as well as against the bacteria of pneumonic plague and tuberculosis. The mask is marked with white or blue elastic bands.
- FFP3: The filtration is not less than 99% and is the highest protective mask which filters out very fine particles but does not offer protection against gases as nitrogen oxide. The mask is marked with red elastic bands.
Courtesy of Ronny Verdoodt
Founder at A Heart for China - Charity Volunteer Organisation