Above information is published by Mrs. Neenu Jacob, Sr. Consultant (Medical Device Regulations) email: nj@i3cglobal.in
Barrier Performance Classification of Medical Face Masks – An Overview
The medical face masks are protective clothing designed to protect portions of the wearer’s face, including the wearer’s nose and mouth, from contact with blood and other body fluids during healthcare services such as surgery and patient care. The ASTM F2100 standard includes testing and requirements for materials used in the construction of medical face masks. This standard ensures minimum performance requirements by the materials used for the construction of the medical face masks.
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The medical face masks are classified into Level 1, Level 2 or Level 3 based on the barrier performance properties of the materials used in the construction. Different tests are performed and the results are evaluated for classifying the masks. The tests performed are as listed below:
- Bacterial Filtration efficiency (BFE) test measures the efficiency of the medical mask material to prevent the passage of aerosolized bacteria as per the standard ASTM F2101-19.
- Particulate Filtration Efficiency (PFE) test measure the effectiveness of the filter material in stopping aerosolized part as per the standard ASTM F2299-03.
- Fluid Resistance measures the mask’s ability to resist penetration of synthetic blood under pressure (in mmHg) and potentially coming into contact with the wearer as per the standard ASTM F1862.
- Differential pressure test measure the pressure drop across the medical face mask, which is an indication of the ease with which air flows from one side of the mask to another, as per the standard EN 14683 (Annex C) or MIL-M-36954C. Higher values indicate that it is more difficult for air to pass through.
- Flammability test pertains to characteristic of the mask material’s ease of ignition and the sustenance of combustion. This test is performed as per 16 CFR 1610.
The results of these determine the barrier protection level of the medical face mask according to the standard ASTM F2100. The acceptance criteria for each level is given in the table below:
| Characteristic Evaluated | Level 1 | Level 2 | Level 3 | |
| 1 | Bacterial filtration efficiency | ≥ 95% | ≥ 98% | ≥ 98% |
| 2 | Particulate filtration efficiency | ≥ 95% | ≥ 98% | ≥ 98% |
| 3 | Fluid resistance (minimum pressure in mm Hg for pass result) | 80 | 120 | 160 |
| 4 | Differential pressure (in mm H2O/ cm2) | <5.0 | <6.0 | <6.0 |
| 5 | Flammability | Class I | Class I | Class I |
For a mask to claim as having a particular barrier performance level, all the tests should meet the criteria for that particular level. If even a single test do not pass the criteria for the claimed level, the lower barrier performance level is assigned to the medical face mask.
List of Standards
- ASTM F2100- Standard Specification for Performance of Materials Used in Medical Face Masks.
- ASTM F2101-19- Standard Test Method for Evaluating the Bacterial Filtration Efficiency (BFE) Of Medical Face Mask Materials, Using a Biological Aerosol of Staphylococcus Aureus.
- ASTM F2299-03- Stand test method for determining the initial efficiency of materials used in medical face masks to penetration by particulates using latex spheres.
- ASTM F1862/ F1862M-17- Standard Test Method for Resistance of Medical Face Masks To Penetration By Synthetic Blood (Horizontal Projection Of Fixed Volume At A Known Velocity).
- EN 14683 (Annex C): 2019- Medical Face Masks – Requirements And Test Methods.
- MIL-M-36954C- Method 1 Military Specifications: Surgical Mask disposable.
- CFR 1610- Standard for the Flammability of clothing textiles
