Bacterial Filtration Efficiency, to BS EN14683:2019+AC:2019 Section 5.2.5, is a measure of the resistance of a material to bacteria penetration. The results are reported as percent productivity and are related to the fabric's ability to resist bacterial penetration.
The test is used to determine the amount of infective agent that is retained by the face mask.
A six-stage cascade impactor and an aerosol chamber are used to carry out this testing. An aerosol pathogen of Staphylococcus Aureus is introduced into the aerosol chamber and drawn through the mash material, and the impactor under the vacuum. The results are given as a percentage. The higher the percentage, the more the mask prevents the passage of bacteria.