Level 3 Masks Are the Highest Level Medical ASTM Masks
With so many types of masks out there, it can get a bit confusing what all the specifications and labels mean. In this article, we tackle the confusing world of surgical/medical ASTM masks and the ASTM standards that determine if a medical mask meets the stringent testing needed to be called a level 3 mask.
First, what is a medical mask?
How does the FDA judge a medical masks' performance?
It is recommended by the FDA, who regulate the marketing and sale of medical devices, that medical masks are tested for the following criteria:
- Differential Pressure
- Particulate Efficiency
- Bacterial Filtration Efficiency
- Fluid Resistance
This is where the ASTM enters the picture.
The FDA endorses ASTM tests as the standard used in the United States for medical masks. This means in order to be categorized as a medical mask, masks must satisfy the following ASTM tests listed below.
Bacterial Filtration Efficiency (BFE) of ASTM Masks (ASTM F2101)
ASTM masks are tested to see the filtration rate when encountering aerosol particles that contain bacteria. The test uses 3.0-micron droplets that contain Staph. Aureus bacteria, which are 0.6-0.8 microns on average. Medical masks need to have a minimum filtration rate of 95% to be considered an ASTM Level 1 mask. Level 2 and level 3 masks need to filter at least 98%.
Particulate Filtration Efficiency (PFE) of ASTM Masks (ASTM F2299)
This ASTM test determines the filtration rate of particles that are 0.1 microns in size to simulate performance against viruses that are similar in size. Once again, to be considered a level 1 medical mask, a filtration rate of 95% must be achieved and a filtration rate of 98% or over must be reached for level 2 and level 3 mask categorization.
Mask Fluid Resistance Testing of ASTM Masks (ASTM F1862)
To determine how resistant the medical masks are to fluid penetration, the tests use synthetic blood at different pressures to see if the fluid will pass through the outer layer. This simulates splashing or spraying that may occur in a medical environment. Masks must withstand the pressure of 80 mm Hg to be considered Level 1 medical masks, 120 mm Hg for level 2 masks, or 160 mm Hg to be called a level 3 mask.
Flame Resistance of ASTM Masks (16 CFR Part 1610)
Medical masks must be able to withstand brief exposure to heat and flame at a certain distance as set by the ASTM to mitigate flammable risks inside a hospital or health clinic, where heat, oxygen, and other flammable sources exist. To be considered a medical mask, the test must determine that the mask is Class 1.
Face Masks Pressure Differential (Delta P) of ASTM Masks (MIL-M-36954C)
The Delta P test is measured by mm H2O/cm2, and determines the breathability of the masks and how much airflow is restricted. Masks that score low values on this test will feel more breathable. Level 1 masks must have a Delta P of less than 4.0, while level 2 and level 3 masks which are more protective have a slightly less restrictive measurement and must be below 5.0.
Why Level 3 Masks are the highest standard for ASTM Masks.
Level 1: Although considered medical masks, they are considered low barrier and are suitable for procedures with low amounts of fluids or aerosol exposure. Examples of use include making dental impressions, performing patient exams, cleaning the operatory, or orthodontic procedures.
Level 2: These medical masks would fall into the moderate barrier category. They would be used for procedures where light or moderate amounts of blood, fluid, and spray are produced, such as endodontic work, sealants, prophylaxis, and some limited surgeries.
Level 3: Level 3 masks are considered a high barrier. They are ideal for procedures with a moderate or high amount of fluid, blood, aerosols, or spray exposure. Common procedures where level 3 masks are suitable will include implant placement, complex surgery, and crown preparation.
Medical masks that meet the level 3 ASTM standard are highly resistant to fluids, offer the highest level of bacterial and particulate filtration, mitigate flammable risks, and meet breathability tests for extended wear during medical and dental procedures. As procedures always present unknown factors, it is not uncommon for many to choose to exclusively use level 3 masks when they are available to have the best protection.