Surgical masks. Requirements and test methods (UNE-EN 14683: 2019 + AC).

Test not accredited in our laboratory.

The transmission of infectious agents can occur in several ways: air, direct contact, inoculation, ingestion, insect or other arthropod bites, animal bites, etc. The most frequent source of infection is the airway through secretions from the upper respiratory tract, such as those coming from the nose (nostrils and nasopharynx) and from the mouth (oral, pharynx or other deeper airway locations). When a person speaks, coughs, sneezes, etc., he releases droplets (Wells´ droplet nuclei) of secretions from the mucous membranes of the mentioned locations. The diameter of most of the droplets is between 0.5 µm and 12 µm, with the largest droplets especially being those that may contain microorganisms from the mucous membranes. The droplets can spread through the air to a location reaching an open surgical wound, sterile surgical instruments, or the mucous membranes of the airways, conjunctiva, and even the skin of another individual.

A surgical mask is a medical device that covers the mouth and nose, providing a barrier to minimize the direct transmission of infectious agents between the surgical staff and the patient. The main intended use of surgical masks is to protect the patient from infectious agents that may be emitted by healthcare personnel. In addition, in certain circumstances, they can also protect the user against splashes of potentially contaminated liquids from a patient or another person in their environment. They can also be used for patients and others to wear to reduce the risk of spreading infection, particularly in epidemic or pandemic situations.

Document UNE-EN 14683: 2019 + AC, specifies the construction, design, operating requirements and test methods of surgical masks intended to limit the transmission of infectious agents from medical personnel to patients during surgical procedures or in other medical settings with similar requirements.

Surgical masks are classified into two types (I and II), depending on their Bacterial Filtration Efficiency (BFE) and their Breathability. Type II is further subdivided depending on whether or not the mask is splash resistant (Type IIR: splash resistant).

The BFE measures the effectiveness of a surgical mask to capture aerosol droplets that can be emitted by health professionals, or others who wear the mask. Thus, type I masks, with a lower BFE, are recommended only to be used by patients or others to reduce the risk of spreading infections in epidemic or pandemic situations and are not indicated for use by health professionals in operating rooms or other medical settings. Type II masks, with increased filtration efficiency, are intended for use by healthcare professionals in an operating room or other medical environment with similar requirements.

Breathability is an indicator of wearing comfort, and is measured as differential pressure. It is used to measure the air exchange pressure of the material of the surgical mask. Finally, resistance to splashes aims to assess the protection offered by masks against exposure to blood and other body fluids, by analyzing the resistance of the masks to the penetration of synthetic blood.

Performance requirements and test methods

Listed below are the operating requirements for different types of surgical masks and test methods.

Operating requirements for surgical masks

Assay

Type I

Type II

Type IIR

Bacterial filtratio efficacy (BFE)

EN 14683: 2019 standard

≥ 95%

≥ 98%

≥ 98%

Breathability or differential pressure

EN 14683: 2019 standard

< 40

> 40

> 60

Splash resistance pressure

EN 14683: 2019 standard

ISO 22609 /ASTM F1862

Not required

Not required

≥ 16 KPa

Microbial cleaning or biological load

UNE-EN 14683: 2019 standard

EN ISO 11737-1: 2018 standard

≤ 30 CFU/g

≤ 30 CFU/g

≤ 30 CFU/g

In addition to these performance requirements, the Biocompatibility of the mask must be evaluated, following EN ISO 10993-1: 2009, for surface devices with limited contact (ENAC accredited tests in our laboratory).

In vitro Determination of Bacterial Filtration Efficiency (BFE)

In this test, a sample of the mask material is attached to a six-stage cascade impactor. The cascade impactor is located between an aerosolization chamber in which an aerosol containing the Staphylococcus aureus bacteria is generated and a vacuum generating sucker. In this way the aerosol with the bacteria is passed through the mask material. The bacterial filtration efficiency of the mask is given by the number of colony forming units (CFUs) that pass through the material of the surgical mask, expressed as a percentage of the number of CFUs present in the inoculation spray.

To perform the test, test samples must be cut from full face masks. A full mask can be used in place of a cut sample, provided that by removing the ends the mask can be laid out flat and all of its layers incorporated. In the case of being folded masks, the mask must be unfolded to test a surface as flat as possible. Each sample should be 100 mm x 100 mm in size and should include all layers of the mask in the order in which they are placed on the entire mask. The test must be carried out at least five times (5 samples), but this number can be greater and must be increased if necessary to allow obtaining an acceptable quality level (AQL: Acceptable Quality Level) of 4%. All samples tested should be taken from representative areas to incorporate all possible variations in filtration depending on the area of ​​construction. Unless otherwise indicated, the assay should be performed with the interior of the surgical mask in contact with the bacterial inoculation material.

All tests must be carried out using finished products or samples cut from finished products. For thick and rigid masks such as rigid or cup-shaped duckbill masks, this test method may not be suitable since complete adaptation cannot be achieved in the cascade impactor used in the evaluation of filtration efficiency Bacterial (BFE: Bacterial Filtration Efficacy). In these cases, another valid equivalent method must be used to determine the BFE.

When a mask consists of two or more areas with different characteristics or different layer composition, each part or area must be tested individually. The part or area whose characteristics offer the lowest level of performance should determine the BFE value of the complete mask.

Determination of Breathability (differential pressure)

To determine Breathability, a device is used that measures the pressure difference necessary to pass a constant air flow through an area of the material of the surgical mask. For this, the test sample is placed on a support, through a 25 mm diameter hole, perpendicular to the air flow. The sample is subjected to a constant flow of air and the pressure difference on both sides of the test sample is determined by means of manometers. Unless otherwise indicated, the test should be performed so that the direction of air flow is from inside the mask to the outside.

Test specimens are full face masks or must be cut from full face masks. If a full mask is used, the extremities are removed and the mask is placed flat so that all layers are incorporated. At least 5 samples must be analyzed, but it can be higher and should be higher if an AQL level of 4% is required. Each sample must be capable of providing at least 5 test areas 25 mm in diameter. If a sample cannot provide 5 test areas, the number of test areas should be representative of the mask size. For thick and rigid masks, this test method may not be suitable as they will not allow a proper seal on the specimen holder. All samples to be tested must be taken from representative areas of the masks that incorporate all/any variations in their construction.

Determination of the splash resistance pressure

ISO 22609 and ASTM F1862 standards, on which the former is based, describe the test method for determining the resistance to penetration of synthetic blood under high-speed liquid contact for a short period of time. To perform this test, a surgical mask sample is placed on a holder and a volume of synthetic blood is sprayed horizontally to simulate the scene of a mask spattered by a perforated blood vessel. ISO 22609/ASTM F1862 describes the volume of fluid to be used, the distance to impact, the size of the hole and the speed of the fluid to be consistent with this healthcare scenario. Any evidence of synthetic blood penetration into the side of the medical mask in contact with the user´s face implies the mask does not pass the test.

According to ISO 22609/ASTM F1862, medical mask samples are evaluated at a total of three different rates corresponding to human blood pressures of 10.6 kPa, 16.0 kPa and 21.3 kPa. Test results are reported at each speed and the surgical mask is rated with the highest blood pressure for which surgical mask samples demonstrate an acceptable quality limit (AQL) of 4.0%. According to the UNE-EN 14683 standard, surgical masks must, at least, pass the test with the average speed, demonstrating resistance to a pressure of 16 KPa.

Full face masks should be used for this test as a test sample. If different materials or material thicknesses are specified in different locations in the design of a medical mask, each area of ​​the sample should be tested separately. If seams are claimed to offer the same protection as base materials in the design of a medical mask, these areas of the mask should be analyzed separately.

A sufficient number of samples taken at random for each type, design, or batch of masks should be tested to achieve an AQL of 4.0%, at each selected test pressure (about 32 samples for a single analysis).

Microbial cleaning (biological load)

The biological load of a surgical mask is evaluated according to EN ISO 11737-1: 2018 and must be ≤ 30 CFU/g. In the microbial cleaning test, the entire mask must be weighed to include it in a volume of liquid culture medium in which it is kept under agitation to extract the microorganisms that it may contain. The liquid medium is subjected to duplicate filtration to retain the microorganisms in the respective filters and then the filter is cultivated, both in culture media for bacteria and fungi. From the cultures, the counts in CFU of the total biological load of each mask are expressed. In the test report, the total biological load per individual mask and the total biological load per gram based on the mask weight are indicated.

The number of masks to be evaluated is a minimum of 5 from the same batch. The samples of the mask used for must be sent in their original primary packaging (dispenser box or equivalent), as offered to the end user. To carry out the test with 5 samples from the same batch, the upper sample, the lower sample and 3 randomly selected masks are taken. If the mask contains a visor or other accessories, these should be included in the tests.

Cost of the tests (with 5 units evaluated by the test from the same batch)

  • Basic price for bacterial filtration efficiency (BFE): Consult to ivami@ivami.com. 
  • Basic price for determining the total biological load (bacteria and fungi): Consult to ivami@ivami.com. 
  • Basic price for breathability (differential pressure): Consult to ivami@ivami.com. 
  • Basic price for determining the splash resistance pressure: Not currently performed. 

Basic price

It is applied for each sample submitted to the test/s with 5 units from the same batch evaluated per test.

Form with the characteristics of the product and material necessary to carry out the tests

The applicant must provide a complete container for each requested test containing the product (masks) under evaluation, so that the laboratory takes the 5 units necessary to perform each requested test, following the selection system recommended by the standard. At the same time it will provide the completed form with all the characteristics that you want to appear in the report.

Results delivery

It will be approximately 10 working days, from the reception in our laboratory of the sample and the form with the requested conditions for the test. If we have the results before we will notify you. The time is based on the tests that are being carried out at the time of receiving the samples.