BFE (Bacterial Filtration Efficiency) Test

The purpose of the Bacterial Filtration Efficiency (BFE) Test, in which Staphylococcus aureus is used as the challenge organism, is to determine the performance of medical masks. During testing, the S. aureus suspension is aerosolized and supplied to the filtration media at a constant flow rate of 28.3 liters per minute (LPM) or 1 cubic foot per minute (CFM).

With the BFE test, resistance to bacterial penetration can be measured. The test stages are as follows:

• The mask sample is compressed between a six-stage cascade impactor and an aerosol chamber.
• A staphylococcus aureus aerosol is introduced into the aerosol chamber and withdrawn from the mask material and impactor under vacuum.
• Bacterial filtration efficiency (BFE) of the mask is determined by the number of colony-forming units that pass through the medical face mask material, expressed as a percentage of the number of colony-forming units present in the staphylococcus aureus aerosol.

BFE in medical face masks must be at the minimum value in accordance with the relevant standards and regulations. BFE testing is performed on products such as face masks, surgical gowns, headgear, and air filters.