Survival of Microorganisms on HEPA Filters

Abstract

High Efficiency Particulate Air (HEPA) filters are required to minimize the release of microorganisms from laboratories and other settings. This study was carried out to assess whether a range of microorganisms captured on HEPA filters would survive under normal operating conditions. Bacillus atrophaeus (NCTC 10073), Staphylococcus epidermidis (NCIMB 12721), MS-2 coliphage, Escherichia coli (NCIMB 9481), Brevundimonas diminuta (NCIMB 11091), and Aspergillus brasiliensis (ATCC 16404) were individually aerosolized using a Collison nebulizer and captured on HEPA filter material. Clean air was drawn through the loaded filters for 6 days at a constant rate (face velocity of 0.4-0.5 m/s -1 ) for all organisms and for 210 days for B. atrophaeus to simulate the use of a HEPA filter. Pre-packed sterile filters were also contaminated with B. atrophaeus which survived on the HEPA filter material for 210 days with no significant loss of viability. MS-2 coliphage and A. brasiliensis survived over the 6 days with no significant loss of viability. There was a 5-log reduction in viability of S. epidermidis over 6 days, while both Gram-negative bacteria, E. coli and B. diminuta, were not recoverable after 48 hours of exposure. This study highlights the need for risk assessments and rigorous guidelines on the use and handling of air filtration membranes exposed to resistant pathogenic agents to minimize the risks of occupational exposure.

Custom solution for personal protective equipment (PPE) in the orthopaedic setting: retrofitting Stryker Flyte T5 PPE system

“…The HEPA filters have a significantly greater life-span compared with respirator masks even with the potential re-sterilization of masks (12,13). This is a pilot study of the potential modification of SS with HEPA filters and would require further testing to confirm a recommended life-span for operating, establishing timing of regular quality assurance checks on the efficacy of the filters, and possible further modification of the inlet to protect the HEPA filter material (16,17).…”

Exploring the potential of electrostatic precipitation as an alternative particulate matter filtration system in aircraft cabins

“…47 Regarding biological matter, it is well documented that mechanical filtration may present a risk of contamination and proliferation because the surface of fibrous filters, where microorganisms and nutrients accumulate, can represent a suitable ecosystem for microorganisms growth. 35,48 For ESP, research has shown that electrical charging could impair the survival rates of bacterial cells and spores, thus limiting their proliferation. 49,50 Consequently, over the last decade, ESPs have gained increasing attention for the removal of particulate matter (mainly dust particles and airborne microorganisms) in confined indoor spaces.…”

Is atomic layer deposition of silver possible on N95 masks?

“…The shortages of supply and high demand may have increased the price significantly, causing consumers to tend to use them for an extended period of time. However, besides the discomfort feeling and the difficulty in adapting the wearing of face masks for a long time, the SARS-CoV-2 virus may oculate and remain viable on the outer side of the respirator for approximately 3−5 days, but can be as long as 14 days [1] , [2] , thereby the extended use of respirators may increase the risk of infection besides causing unexpected health problems, as air-borne bacteria may also be intercepted by respirators’ filter media [2] , [3] .…”

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