What are ASTM Standards for Medical & Surgical Face Masks? What are the 3 Levels?

What are ASTM Standards for Medical & Surgical Face Masks? What are the 3 Levels?

If you are interested in knowing the ASTM standards for medical masks, you must know ASTM F2100 – 21.

What are ASTM standards for medical face masks?

ASTM standards are important for the medical face mask industry because they provide guidance on how face masks should be manufactured in order to protect people from infection. The most important ASTM standard for medical face masks is ASTM F2100, which provides performance requirements for three different types of masks: Level 1, Level 2, and Level 3. Masks must meet certain filtration and fluid resistance requirements in order to be classified as a medical face mask.

The highest level of protection is provided by Level 3 masks, which are required to have a bacterial filtration efficiency (BFE) of ≥ 98% and a differential pressure of ≤ 160 mm Hg.

ISO 10993-1 is another important standard that provides guidance on the safety of materials that come into contact with human skin.

 

Application of ASTM F2100-21

Standard Specification for Performance of Materials Used in Medical Face Masks

The ASTM F2100 standard is widely used in the United States and other countries as the primary set of guidelines for evaluating the performance of medical face masks, including SARS-CoV-2 (the virus that causes COVID-19). The standard provides three different levels of protection for users, depending on the mask’s intended use:

  • Level 1 for low-risk procedures like drawing blood or administering oxygen;
  • Level 2 for moderate-risk procedures like intubation or dental work;
  • Level 3 for high-risk procedures like open heart surgery.

In order to be certified as meeting one of these levels, a mask must undergo a series of tests designed to measure its ability to protect the wearer from exposure to various airborne contaminants. The most important of these tests is the “filtration efficiency” test, which measures how well a mask can filter out small particles from the air. A mask that passes this test with a filtration efficiency of 95% or higher is considered a “medical grade” face mask.

While the ASTM F2100 standard is primarily designed for use with medical face masks, it can also be applied to other types of personal protective equipment (PPE), such as respirators.

In general, any PPE that is intended to provide respiratory protection (such as against dust, fumes, or chemical vapors) should meet at least the minimum filtration efficiency requirements specified in the standard.

 

How Does the FDA Face Mask Regulation and Policy?

The FDA regulates face masks, medical masks, and surgical masks. They are classified as Class II medical devices. Face masks are designed to protect the wearer from exposure to airborne particles, bacteria, and viruses. Medical masks are designed to protect the wearer from exposure to bodily fluids, including blood, saliva, and mucus. Surgical masks are designed to protect the wearer from exposure to surgical instruments and other objects that may be contaminated with blood or body fluids.

 

How does ASTM test face masks?

ASTM tests face masks by measuring filtration efficiency and breathability. The filtration efficiency is the percentage of particles that are filtered out by the mask. Breathability is the amount of air that can pass through the mask.

  1. To test the filtration efficiency, a standard particle size is used and the mask is placed on a mannequin head. The mannequin is then placed in an aerosol to measure the percentage of particles that are filtered out.
  2. To test the breathability, a mannequin head is placed in a sealed chamber and the air is passed through the mask. The amount of air that passes through the mask is measured. ASTM has different standards for different types of masks.
  3. The standards specify the materials that can be used to make the masks, the performance requirements, and the test methods.

 

Are Surgical Masks Medical Devices?

Classification of surgical masks is based on their design, intended use, and mode of wear. Surgical masks are regulated under 21 CFR 878.4040 as Class II medical devices. A surgical mask must meet certain standards of filtration, breathability, splatter resistance, and splash resistance. Testing and materials used for surgical masks are regulated by ASTM International standards.

Surgical masks are made from a variety of materials, including cotton, polyester, polypropylene, or other synthetic fibers. The material can vary depending on the manufacturer’s preference or the specific requirements for the mask.

ASTM Standards & EN14683Difference between ASTM level 1, 2, and 3 face masks

For EU market, please check out this article about EN 14683.   Let’s take a detailed look at each area and its terminology.

ASTM Standards & it’s Terminology

1. BFE (Bacterial Filtration Efficiency).

BFE is a measurement of how well a medical face mask can filter out bacteria when exposed to a bacteria-containing aerosol.  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%. To determine the BFE rating, some manufacturers use the Modified Greene & Vesley methodology. ASTM does not recommend this method for product comparisons or to evaluate consistency.

2. PFE (Particle Filtration Efficiency)

PFE is a measure of how well a hospital mask filters submicron particles. It is used to predict that viruses will also be filtered in the same way. Higher percentages indicate better mask filtration. ASTM F2100 recommends that testing be done with particles sizes ranging from 0.1 to 5 microns.

It is important to compare test results by looking at the size of the particles.  Larger particles can lead to misleading PFE ratings.

3. Fluid Resistance:

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. ASTM recommends that fluid resistance be tested with synthetic blood at pressures 80, 120, and 160 mm Hg. This allows for the testing to determine if the mask is capable of minimizing fluid transfer from the outer layers to inner layers as a result of a splash or spray. These pressures correspond to blood pressure:

  • 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).

 

4. Delta P (Pressure Differential)

Delta P is an objective measurement of airflow resistance and measures breathability. The Delta P-value is expressed in mm H2O/cm2. The more breathable the mask feels, the lower it will be. ASTM standards require that low-barrier masks have a Delta P less than 6.0.

 

5. Spread the Flame:

Hospitals can contain heat, oxygen, and fuel so ASTM standards require flame resistance testing. All hospital masks must be able to resist flame exposure for at least three seconds.

 

6. ISO Certification:

All medical face masks must pass the above tests and be tested for skin sensitivity (ISO 10993-5, 10) to ensure they are safe. The material used in the construction of the mask comes in contact with the skin.

 

ASTM PROTECTION & INTENDED USAGE

LEVEL 1 (LOW) BARRIER: 80 mm HgLEVEL 2 (MODERATE) BARRIER: 120 mm HgLEVEL 3 (HIGH) BARRIER: 160 mm HgLight / minimum BFE & PFE protection high BFE & PFE protection high BFE & PFE protections for general procedures and respiratory examMore breathable than high barrier mask Designed to resist a splash or spray at venous pressure designed to resist a splash or spray at arterial pressureHighest fluid resistance – designed to resist a splash or spray during tasks like orthopedic surgery or trauma

 

Reference:

  1. 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
  2. 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/
  3. 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/

 

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