Evaluation of Medical Face Masks
BS EN 14683 : 2019 – Medical Face Mask Efficacy Test
EN 14683 assess suitability and effectiveness of face masks for their intended use. This standard is employed to medical face masks designed to curtail transmission of infectious agents between hospital staff and patients, particularly during surgical procedures in operation theaters and similar other situations. To determine medical face mask efficacy, EN 14683 outlines testing requirements and efficacy criteria which ensure level of microbial protection, comfort, breathability, and resilience.
Medical face masks that come within the scope of EN 14683 are classified into the following two groups, Type I and Type II. This classification is based on their Bacterial Filtration Efficiency (BFE).
Type I medical face masks – Intended to be used by patients in order to minimize the risk of infection spread, particularly in epidemic or pandemic situations.
Type II medical face masks – Primarily intended to be used by healthcare professionals in operating rooms or other similar situations/ requirements. Type II masks are subdivided into Type II and Type 11 R according to their ability to protect the wearer against the splashes of potentially contaminated fluids. Herein, R signifies splash resistance.
As per EN 14683 standard, following tests are carried out on finished products or samples cut from finished products.
- Bacterial filtration efficiency (BFE)
- Breathability (delta P)
- Splash resistance (synthetic blood)
- Microbial cleanliness
EN 14683 Test Methods
1. Bacterial Filtration Efficiency (BFE)
The BFE test is performed to determine the resistance of the mask materials and components to bacterial penetration.
Test Requirements and Conditions:
Mandatory test microorganisms – Staphylococcus aureus ATCC 6538.
Test specimen preparation – 5 test specimens of size 100 mm × 100 mm are required for testing. Test specimens should have all layers of the mask in the order in which they are placed in the finished mask. Before testing, each test specimen is held at (21 ± 5) °C and (85 ± 5) % relative humidity for a minimum period of 4 h to bring them into equilibrium with the atmosphere.
Incubation period – 37 ± 2 °C for 20 to 52 h.
Method for Bacterial filtration efficiency (BFE)
- A specimen of recommended size is clamped between a six-stage cascade impactor and an aerosol chamber.
- Aerosolized bacterial suspension (Staphylococcus aureus) is introduced into the aerosol chamber and drawn through the mask material and the cascade impactor under vacuum. The petri plates in cascade impactor collect any aerosolized bacteria which pass through the mask material.
- This procedure is repeated for each test specimen and fresh plates are placed in cascade impactor.
- After all test specimens are tested, a positive control (untreated mask material) and negative control test is performed.
- All the plates are incubated at 37 °C for 20 to 52 h.
- After incubation,viable bacteria from the agar plates are then enumerated using traditional units of bacterial efficiency (CFU) and further converted into a percentage of efficiency.
2. Breathability (differential pressure) Test
This test assesses the breathability of mask materials, specifically evaluating whether wearers can breathe comfortably while wearing them. Breathability of mask is assessed by measuring the pressure differential (also called “pressure drop”) across two sides of a mask.
Sample preparation – 5 test specimens of circular test areas of diameter 25 mm are required for testing. Test specimens should have all layers of the mask in the order in which they are placed in the finished mask. Before testing, each test specimen is held at (21 ± 5) °C and (85 ± 5) % relative humidity for a minimum period of 4 h to bring them into equilibrium with the atmosphere.
Method for determination of Breathability (differential pressure)
- The sample holder is sealed, and the differential manometer is calibrated to zero. The pump is started and airflow rate is adjusted to 8 l/min.
- The holder is opened to clamp up the test specimen in place using a mechanical clamp with a pressure to prevent any air leaks. After specimen placement, it is important to ensure that air flow rate should be 8 l/min as previously adjusted.
- The differential pressure is measured using a differential pressure manometer.
3. Splash Resistance (synthetic blood)
Splash resistance (synthetic blood) helps to determine resistance of medical face masks to penetration by a splash of synthetic blood.
Note – ISO 22609:2004 outlines a test method for measuring the resistance of medical face masks to penetration by a splash of synthetic blood.
When tested in accordance with ISO 22609:2004, EN 14683 recommends that fluid resistance be tested with synthetic blood at pressures 120mm Hg (≥ 16.0).
4. Mask Microbial Cleanliness (Bioburden) Test
The Microbial Cleanliness test helps to measure microbial contamination on the face mask.
Note – ISO 11737-1-2018 specifies requirements and efficacy criteria for sterility testing of product,components, and raw materials intended for use in the medical area. When tested according to EN ISO 11737-1:2018, the bioburden of the medical mask should be ≤ 30 CFU/g.
Method for mask microbial cleanliness (Bioburden)
- Test specimen mask is taken out of packaging aseptically.
- It is further placed in a 500 ml sterile bottle containing 300 ml of extraction liquid. The bottle is placed in an orbital shaker and shaken for 5 min at 250 rpm.
- After the extraction step, 100 ml of the extraction liquid is filtered through a 0.45 μm filter. Filtrate is spread onto the TSA Tryptone Soy Agar (TSA) plate to determine total viable aerobic microbial count.
- Other 100 ml aliquot of the same extraction liquid is filtered and resulting filtrate is plated on Sabouraud Dextrose agar (SDA) with chloramphenicol to enumerate fungal growth.
- Inoculated plates are subjected to an incubation period of 3 days at 30 °C for TSA and 7 days at (20 to 25) °C for SDA plates.
- Number of colonies on TSA and SDA is used to determine the total bioburden of the mask.
5. Biocompatibility Test
Biocompatibility test for medical face masks is performed to determine cytotoxic, allergic or sensitizing reactions of mask materials on the user’s skin.
Note – The biocompatibility of face masks should be analyzed according to ISO 10993-1:2009.
Importance of EN 14683 Test
In medical settings, such as during surgical procedures or similar situations, the transmission of infection through droplets and aerosols is recognised as a potential airborne pathway. The use of face masks is considered to be a strong preventive strategy to mitigate the risk of airborne transmission of infection involving sneezing, coughing, and speaking.
Manufacturers/companies of medical face masks are obligated to provide efficacy data reports to regulatory authorities. EN 14683 is an european standard that specifies performance requirements for medical face masks, ensuring their suitability for intended use. EN standard helps to assess whether tested face masks can effectively block contaminated droplets and other pollutants to protect the wearer from infection, particularly during epidemic or pandemic outbreaks.
Require assistance with EN 14683 testing services for your medical masks! The experts at MIS are ready to assist you.
As a leading global microbiology testing lab, MIS specializes in providing comprehensive medical mask testing services. Our team of proficient professionals excels in devising and implementing test analysis protocols that align with pertinent industry standards and regulations.
The EN 14683 standard specifies the construction, design, performance requirements, and test methods for medical face masks. These masks are intended to minimize the air transmission of infective agents during surgical procedures and in other medical settings with comparable needs.
The EN 14683 test is applicable to evaluate the suitability of medical face masks for use in operating rooms and healthcare settings with similar requirements.
EN 14683 test takes 3-4 weeks to complete.
At Microbe Investigations, we test for EN 14683 using the following bacterial strain: Staphylococcus aureus (ATCC 6538P). Additional strains can be added on customer request.
Contact us for more information
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