Bacterial Filtration Efficiency (BFE) Testing

Scope

BFE testing evaluates face masks, respirators, and filtration media against a standardized bacterial aerosol challenge. The test is conducted in a sealed aerosol chamber with defined airflow, and results are compared against acceptance thresholds specified in the applicable standard. The primary standard is ASTM F2100, which defines three performance levels for medical face masks:

• Level 1 — BFE ≥95%, for low-barrier general use
• Level 2 — BFE ≥98%, for moderate-barrier surgical and procedural use
• Level 3 — BFE ≥98%, for high-barrier use in high-fluid-exposure environments

Additional standards that reference or incorporate BFE testing include:

• ASTM F2101 — the core test method for BFE measurement using S. aureus
• EN 14683 — European standard for surgical masks, incorporating bacterial filtration efficiency requirements
• FDA guidance for surgical masks — references BFE performance data for 510(k) submissions
• ISO 22609 — resistance to penetration by synthetic blood, often evaluated alongside BFE for full surgical mask characterization

Applications

• Medical face mask manufacturing — BFE testing is a mandatory performance requirement for surgical masks sold in the US and EU markets; manufacturers need test data before market entry
• Respirator and PPE development — evaluation of new filtration materials or mask designs during R&D, before committing to full production tooling
• Nonwoven and filtration media suppliers — material-level BFE testing to characterize filter layers and support customers making mask procurement or design decisions
• Healthcare procurement — hospitals and GPOs sourcing masks from new suppliers use BFE data to verify performance claims independently
• Industrial and occupational safety masks — BFE evaluation for masks used in environments with biological aerosol risk, such as animal handling, food processing, or waste management
• Custom and reusable mask evaluation — testing of novel or reusable mask designs where no established performance data exists

Benefits

• Directly relevant to clinical use conditions, the S. aureus aerosol at 3 µm MAD models the droplet size range associated with respiratory transmission in healthcare settings, making BFE results meaningful for infection control decisions
• Required for market access in key regulated markets — US and EU surgical mask requirements reference BFE as a core performance parameter; without it, a mask cannot be marketed for surgical or medical use
• Fast, clear pass/fail output — BFE results are expressed as a single percentage value against a defined threshold, making them straightforward to interpret and communicate.
• Complements PFE and fluid resistance testing — BFE is one component of a complete mask characterization package; labs that run BFE typically also run PFE, differential pressure, and fluid resistance on the same samples.
• Identifies filtration layer performance early — material-level testing catches underperforming filter media before it gets incorporated into finished mask production