Differences between BFE and VFE Testing

Through filtration efficiency testing, masks are given ratings that help determine how effective the materials are at protecting a wearer from aerosols. This gives the wearers a concept of the level of protection they are receiving when wearing a mask.

Filtration efficiency tests are usually stated in terms of the percentage (%) of particles of a certain size that would be stopped and retained by a filter medium. This testing is typically performed on specific types of textiles used in personal protective equipment (PPE), including face masks, medical gowns, air filters. It is necessary to ensure those special types of textiles perform safely and effectively. Manufacturers can also know how well their product works.

What is BFE (Bacterial Filtration Efficiency)?

Bacteria are small single-celled organisms. Bacterial filtration efficiency testing assesses how well a particular material filter out bacteria. It is used to determine compliance with specific standards including ASTM F2100, EN 14683 and ASTM F2101 (ASTM is an organization that sets specific standards for various industries and products). This is the basic standard for the type of material used in medical face masks.

During a BFE test, a part of the fabric is securely clamped between a special cascade impactor and an aerosol chamber. A specific bacterium, usually staphylococcus, is added to the aerosol chamber and is then drawn through the mask using a vacuum.

Test personnel then check the number of bacterial colonies that have passed through the material. This test is repeated several times to determine a comparative average of how the fabric performs. The material is then given a rating based on the test results. Generally, BFE measures how well a material protects against live bacteria particles that measure from one to five microns.

What is VFE (Viral Filtration Efficiency)?

A virus is a small collection of genetic code, either DNA or RNA, surrounded by a protein coat that needs a host to survive. Viruses are also tinier than bacteria. Virtual filtration efficiency (VFE) is nearly identical to BFE. The biggest difference is that a specific virus is used in aerosol form instead of bacteria or particulates.

VFE is exceptionally important in high-grade medical masks when blocking out viruses like COVID-19. The BFE and VFE tests generally go together, with VFE being the lesser-used approach.

When purchasing surgical face masks, it is crucial to take a look at these types of ratings. They can indicate the overall effectiveness of the masks. The VFE and BFE of our masks (ResproShield Surgical Face Mask Level 3 - Blue, ResproShield Kids Surgical Face Mask Level 3 - Blue, ResproShield Surgical Face Mask Level 3 - Black, ResproShield Surgical Face Mask Level 2 - Blue) are reported up to >99.9%. You can rest assured that our products can protect you and your family.