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Post-BFE Testing (custom)

Purpose and Goals

  • Evaluate and compare the antimicrobial efficacy of filter samples (such as HVAC filters, face masks, and other filtration media) after bacterial filtration efficiency (BFE) testing. 
  • Determine how well an integrated antimicrobial agent acts on filtration-captured aerosolized droplets of bacteria, as this effect differs from that on liquid bacterial suspensions (such as AATCC TM 100, ASTM E3160, ISO 20743 or JIS L 1902).


  • This custom test will be performed after the standard BFE testing is used to deposit aerosolized bacteria onto the filter sample.
    • Standard BFE Test Methods include ASTM F2101-22, ISO 14683:2017, & BS EN 14683:2019.
  • The filter sample is then placed into a test tube with sterile nutrient solution and incubated for 24 hours.
    • This incubation step allows any bacteria captured within the filtration material to grow, but also allows the antimicrobial agent contact time to affect any such growth.
  • Each test sample is then neutralized and any remaining bacteria are recovered into a solution which is dilution-plated onto nutrient agar to provide quantifiable bacterial burden results.
  • The results from a filter sample with the antimicrobial agent are compared with the results from a filter sample without any antimicrobial agent (untreated control).
  • Testing will include 12 total data points:
    • 2 materials (filter with antimicrobial agent and untreated control filter)
      • Please provide materials with the same base composition and structure to achieve similar filtration rates (BFE %) and consistent initial captured bacterial burden in each material.
    • 2 time-points (0 and 24 hours Post-BFE)
    • 3 replicate swatches at each test condition

Data Analysis

  • Data will be calculated to determine the quantifiable bacterial burden in colony-forming units per sample remaining on each test sample.
  • Data will be analyzed to determine the consistency between replicate filters (sample size n=3).
  • Data will be analyzed to determine the percent reductions and log reductions of bacterial burdens on each test material compared to the negative control at each test condition.

Turn Around Time

  • 2-4 weeks