EN 14683

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.