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We would like to thank Primed for the comprehensive questions and answers below regarding medical earloop masks.


What is ASTM?

ASTM refers to the American Society of Testing and Materials American Society of Testing and Materials (ASTM). ASTM is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services—including those in healthcare.



What are ASTM standards for medical face masks?

ASTM standards are referenced by the Food and Drug Administration (FDA), as the endorsed standard in the United States. ASTM F2100 specifies the performance requirements for Medical Face Masks with five basic criteria:

1. BFE (Bacterial Filtration Efficiency):

BFE measures how well the medical face 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 must have bacterial filtration rates greater than 98%.

Some manufacturers use the Modified Greene & Vesley method to determine the BFE rating. This method is NOT recommended by ASTM for product comparison or evaluating consistency.



3. Fluid Resistance:

Fluid resistance reflects the surgical 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 (Level 1), 120 mm Hg = arterial pressure (Level 2), and 160 mm Hg (Level 3) correlates to potential high pressures that may occur during trauma, or surgeries that include high pressure irrigation such as orthopedic procedures.



2. PFE (Particulate Filtration Efficiency):

PFE measures how well a hospital 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 filtration.


Although testing is available using a particle size from 0.1 to 5.0 microns, ASTM F2100 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.


4. Delta P (Pressure Differential):

Delta P measures the air flow resistance of the medical mask and is an objective measure of breathability. The Delta P is measured in units of mm H2O/cm2 and the lower the value the more breathable the mask feels.


The ASTM standard requires that masks have a Delta P of less than 6.0 for moderate and high barrier masks, whereas low barrier masks must have a Delta P of less than 5.0.


5. Flame Spread:

As hospitals contain sources of oxygen, heat, and fuel the ASTM standards include testing for flame resistance.


Testing dictates that all hospital masks must withstand exposure to a burning flame (within a specified distance) for three seconds. All PRIMED masks meet this requirement.



5.5 ISO Certification:

In addition to the above tests, all medical face masks must be tested to an international standard (ISO 10993-5, 10) for skin sensitivity and cytotoxic tests to ensure that no materials are harmful to the wearer. Tests are conducted on materials used in construction of the mask which come in contact with the user's skin.



Are there different levels of protection with ASTM-rated medical masks?

Yes, there are three unique levels of protection with ASTM-rated medical masks.


Level 1 masks have the lowest barrier of protection, while Level 3 masks have the highest barrier of protection. For greater clarity on the differences, refer to the information below:



80 mm Hg

  • Light / minimum BFE & PFE protection
  • Used for general procedures and respiratory etiquette
  • Designed to resist a splash or spray at venous pressure


120 mm Hg

  • High BFE & PFE protection
  • More breathable than high barrier mask
  • Designed to resist a splash or spray at arterial pressure


160 mm Hg

  • High BFE & PFE protection
  • Highest fluid resistance – designed to resist a splash or spray during tasks like orthopedic surgery or trauma





80 mm Hg


120 mm Hg


160 mm Hg

BFE (Bacterial Filtration Efficiency)
at 3.0 micron ASTM F2101


≥ 95% ≥ 98% ≥ 98%

PFE (Particulate Filtration Efficiency)
at 0.1 micron ASTM F2299


≥ 95% ≥ 98% ≥ 98%

Delta P (Differential Pressure)
MIL-M-36954C, mm H2O/cm2


< 5.0 < 6.0 < 6.0

Fluid Resistance to Synthetic Blood ASTM 1862, mm Hg


80 120 160

Flame Spread
16 CFR part 1610


Class 1 Class 1 Class 1



What tests or ratings should I rely on to ensure my mask is safe?

Specifications developed by the American Society of Testing and Materials (ASTM) are generally accepted as the industry standard. Beware of mask ratings that do not follow ASTM guidelines.


Some manufacturers may refer to “filtration rates” or the “number of layers” as an indication of effectiveness. These vendors may not be adhering to the ASTM standards and should be questioned for specific test data.


What is the difference between a medical mask and a respirator?

Medical masks (surgical/procedure masks) are loose fitting masks that cover the mouth and nose. They are designed to stop large droplets and splashes or sprays, but are not designed to seal tightly to the face or filter small airborne contaminants.

A respirator is an item of PPE designed to reduce exposure to airborne contaminants. Known airborne pathogens include TB, SARS, Anthrax, and Hantavirus.


Respirators must be individually selected to fit the wearers face and shown to provide a good seal. They also must be certified by NIOSH, and used within a comprehensive respiratory program including fit testing and training.




How long is my medical face mask effective?

The filtration efficiency and protective ability of a face mask is compromised when the mask becomes wet, torn or dislodged.


Generally speaking, the higher protection value of a mask, the longer it will maintain filtration; however, there is no set rule for how long a mask should be worn as it depends on humidity levels, respiration rate, nasal discharge, talking, etc.


A medical face mask should be worn for only one patient procedure or visit. If a mask gets wet or soiled it should be replaced.


What is the difference between a surgical mask and a procedure mask?

A surgical mask is used inside the operating room or within other sterile procedure areas to protect the patient environment from contamination.


It also protects the clinician from contaminated fluid or debris generated during the procedure. Surgical masks have ties so that they can be adjusted for fit, and are tied over top of a surgical cap or a bouffant cap.


A procedure mask is used for performing patient procedures, or when patients are in isolation to protect them from potential contaminants. Procedure masks are used to protect both patients and staff from the transfer of respiratory secretions, fluids or other debris.


Procedure masks are used for generally "respiratory etiquette" to prevent clinicians, patients and visitors from spreading germs by talking, coughing, or sneezing. Procedure masks have earloops for quick donning, and since they do not slide on the hair, they can be worn without a surgical cap.




Why is the fit of a medical face mask important?

A mask is only as effective as its fit.


There should be no gaps along the side, around the nose or under the chin that would allow air and droplets to bypass the filter medium. The mask should always be properly adjusted to fully cover both the mouth and nose.


A well-fitting mask stays in place over the nose and cheeks and even a regular mask will prevent fogging of eyeglasses if it fits properly. Masks should not be worn underneath the nose or dangling around the neck – they should either be fully on, or disposed of.