Survival of Microorganisms on HEPA Filters

HEPA filters are crucial components of laboratory air filtration systems, safeguarding personnel and the environment by capturing airborne contaminants like bacteria and viruses. Maintaining a sterile environment is critical in various settings beyond laboratories, such as hospitals, cleanrooms, and pharmaceutical production facilities. This study investigated the survival of various microorganisms collected on HEPA filters under simulated real-world conditions to assess the effectiveness of these filters in minimizing microbial release from these sensitive environments.

Microorganisms tested:

  • Bacillus atrophaeus
  • Staphylococcus epidermidis
  • MS-2 coliphage
  • Escherichia coli
  • Brevundimonas diminuta
  • Aspergillus brasiliensis

These microorganisms were aerosolized using a Collison nebulizer and then collected on HEPA filter material.

Testing:

  • Clean air was passed through the loaded filters for 6 days at a constant rate for most organisms.
  • B. atrophaeus was tested for 210 days to simulate extended use.
  • Additionally, pre-packed sterile filters were contaminated with B. atrophaeus and monitored for survival over 210 days.

Results:

B. atrophaeus exhibited remarkable resilience, surviving for 210 days with no significant loss of viability in both tests. MS-2 coliphage and A. brasiliensis also demonstrated extended survival, persisting for 6 days with minimal viability loss. This highlights the importance of proper HEPA filter maintenance and replacement schedules to ensure their effectiveness in capturing and preventing the release of even highly resilient microorganisms. Other organisms like E. coli and B. diminuta showed reduced viability after 2 days, while S. epidermidis viability declined within 6 days.

HEPA Filters in Labs:

HEPA filters play a critical role in laboratory safety by capturing and preventing the release of airborne pathogens from the HVAC system. They are regularly tested for integrity and efficiency to ensure proper performance.

Handling HEPA Filters:

When handling or replacing HEPA filters for testing or removal, there is a potential risk of exposure to microorganisms that may have been trapped on the filter surface. This highlights the importance of appropriate safety protocols during filter maintenance.

Resources: https://www.researchgate.net/publication/291598124_Survival_of_Microorganisms_on_HEPA_Filters

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