Short for bacterial filtration efficiency. A spray of droplets carrying Staphylococcus aureus, averaging about 3 micrometers, is pushed through the material and the bacteria that pass are counted against a control. Medical face mask grades typically call for at least 95 or 98 percent, which in practice depends on a charged meltblown layer. It is often reported next to particle filtration efficiency (PFE), which uses much smaller test particles.
Mask media passes BFE at 99 percent but PFE slipped after storage, so the charge is decaying.
Also heard as
- bacterial filtration efficiency
Related terms
Electret
Filter fabric, usually meltblown, carrying a long-lasting electrostatic charge that pulls particles out of the air.
Meltblown
Web of very fine fibers made by blasting molten polymer from a row of tiny die holes with hot, high-speed air.
Air permeability
Rate of air flow through a fabric at a fixed pressure difference, reported per unit area.