ASTM F2101

ASTM F2101 Test Methods and Requirements:

• Test organism: Staphylococcus aureus is a bacteria, that forms a part of our normal body flora and acts as an opportunistic human pathogen. Staphylococcus aureus is the leading cause of infections contracted within the hospital and hence used for BFE testing.
• BFE testing introduces aerosolized bacteria into an aerosol chamber using a nebulized culture suspension of 5 × 10^5 CFU/mL Staphylococcus aureus.
• The Staphylococcus aureus aerosol is drawn through the medical face mask material within the aerosol chamber by a vacuum attached to the cascade impactor.
• Perform a positive control run without a test specimen clamped into the test system to determine the number of viable aerosol particles generated.
• The aerosol’s mean particle size (MPS) is calculated from the results of these positive control plates.
• For testing, a medical face mask material sample is clamped between a six-stage cascade impactor in an aerosol chamber.
• After cascade impactor sampling, the agar plates are incubated for a period of 48 hours.
  After incubation, the number of viable particles collected on each of the six-stage plates of the cascade impactor is counted.
• The bacteria collected from the agar plates are quantified using traditional bacterial efficiency units (CFU) and then converted into a percentage to represent filtration efficiency.
• The bacterial challenge solution is nebulized at approximately 1700 to 3000 viable particles per test to determine the correct CFU units of bacterial efficiency.
• The challenge delivery rate is based on the results of the positive control plates when the aerosol is collected with no test material specimen clamped into the testing system.
• Perform a negative control sample by collecting a 2-minute air sample from the aerosol chamber. No bacterial challenge should be pumped into the nebulizer while collecting the negative control sample.
• Incubate agar plates at 37± 2 °C for 48 ± 4 h.