ASTM F2100 - 21
This specification covers the classifications, performance requirements, and test methods for the materials used in the construction of medical face masks that are used in health care services such as surgery and patient care. Medical face mask material performance is based on testing for bacterial filtration efficiency, differential pressure, sub-micron particulate filtration efficiency, resistance to penetration by synthetic blood, and flammability. This specification does not address all aspects of medical face mask design and performance, the effectiveness of medical face mask designs as related to the barrier and breathability properties, and respiratory protection, which may be necessary for some health care services.
This test indicates how well a mask filters droplets containing biological agents such as bacteria or viruses. With SARS-CoV-2 thought to be transmitted through droplets, the BFE test is a proxy for the efficacy of a mask in preventing such transmission.
Studies indicate that a cough typically expels droplets between 5 and 20 microns in size. The BFE test measures how effectively a mask filters bacteria-containing droplets about 3 microns in size. (An average human hair is about 70 to 100 microns wide.)
ASTM recommends that the droplet containing Staph Aureus (average size 0.6-0.8 microns) be tested. To be called a medical/surgical mask minimum of 95% filtration is required. High protection and moderate masks should have bacterial filtration rates of at least 98%.
The PFE test is the measurement of how well it filters airborne particles such as pollen or dust. This is measured by filtering particles about 0.1 micron in size.
The higher the PFE of a mask, the more particles it filters. If it can filter particles about 0.1 micron wide, it is likely to be able to filter droplets that are typically much larger, and which might contain SARS-CoV-2.
ASTM F2100 recommends that testing be done with particles sizes ranging from 0.1 to 5 microns.
The masks wearing user experience is related to the differential pressure. The lower the DP of a mask, the more breathable it is.
This test determines how breathable a mask is by measuring how easily air passes through from one side to the other. It is to calculate the difference in pressure across the surface at a flow rate of 8 litres per minute.
ASTM standards require that low barrier masks have a Delta P less than 6.0.
Fluid resistance is the ability of the surgical mask to reduce fluid transfer from outer layers to inner layers as a result of splashes or sprays.
The mask is examined to determine whether any synthetic blood has penetrated the mask. If no synthetic blood has penetrated the mask, the product is deemed to have passed the test.
ASTM recommends that fluid resistance be tested with synthetic blood at pressures 80, 120, and 160 mm Hg.
80mm Hg = vein pressure (Level 1)
120mm Hg = arterial pressures (Level 2);
160mm Hg =Correlates with high pressures that could occur during trauma or surgery that includes high-pressure irrigation, such as orthopedics (Level 3).
ASTM's fire and flammability standards are involved in the testing and evaluation of the ignition, burning, or combustion characteristics of mask.
All medical and surgical masks must be able to resist flame exposure for at least three seconds.
Micro Biological Evaluation
All medical and surgical must pass the above tests and be tested for skin sensitivity, skin irritation and cytotoxicity (ISO 10993-5, 10) to ensure they are safe. The material used in the construction of the mask comes in contact with the skin.
All the information contained in this article is for general reference purposes. Kingfa Medical does not guarantee the accuracy, relevance, and timeliness of any information, and the company does not assume any responsibility for errors or omissions in this article.
ASTM F2100 – 21 Standard Specification for Performance of Materials Used in Medical Face Masks. (n.d.). ASTM. Retrieved August 18, 2021, from https://www.astm.org/Standards/F2100.htm
Bacterial & Viral Filtration Efficiency Tests. (n.d.). Nelson Labs. Retrieved August 18, 2021, from https://www.nelsonlabs.com/testing/bacterial-viral-filtration-efficiency-bfe-vfe/
Particle Filtration Efficiency (PFE) Test | Nelson labs. (n.d.). Nelson Labs. Retrieved August 18, 2021, from https://www.nelsonlabs.com/testing/particle-filtration-efficiency-pfe/