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Bioaerosol collection efficiency for different filter materials using Bacillus atrophaeus and MS2 bacteriophage as bioterrorism surrogates.

Burton NC; Adhikari A; Grinshpun SA; Reponen T
Proceedings of the Seventh International Aerosol Conference, September 10-15, 2006, St. Paul, Minnesota. Biswas P, Chen DR, Hering S, eds. Mount Laurel, NJ: American Association for Aerosol Research, 2006 Sep; :959
The environmental sampling conducted during the 2001 anthrax bioterrorism events in the United States showed a need to characterize the efficiency of filter sampling against bioterrorism agents (CDC, 2002). We conducted a laboratory study to investigate the collection efficiency of various filter media for bacterial and viral bioterrorism surrogates. METHODS: Aerosolized Bacillus atrophaeus (Bacillus subtilis subsp. niger endospores, also known as Bacillus g/ogigii rBG]), were used as a surrogate for B. anthracis. MS2 bacteriophages were utilized as a viral surrogate in the testing. B. atrophaeus endospores have an aerodynamic diameter of 0.9 /lm (Clark Burton et aI., 2005) whereas the peak mobility diameter of the MS2 virions was 30 nm. Monodisperse 0.35 /lm polystyrene latex (PSL) particles were also used in the testing. The test particles were aerosolized using a Collison 6-jet nebulizer. The following filters were tested: gelatin filters (3 /lm pore size), poly carbonate (PC) (I and 3 /lm pore size), and polytetrafluoroethylene (PTFE) filters (of 0.3, I, and 3 /lm pore sizes). All filters except the 0.3 /lm PTFE were used in conjunction with Button Inhalable Aerosol Samplers operated at a flow rate of 4 Llmin. The 0.3 /lm PTFE filter was preloaded in a 37-mm 3 three-part styrene cassette, which was operated at a flow rate of 2 Lpm. Physical collection efficiency (PCE) was determined by measuring the concentration of endospores and MS2 particles upstream and downstream of the filter sampler with an optical particle counter (Grimm Technologies, Inc.) or a WideRange Particle Spectrometer (MSP Inc.), respectively. RESULTS AND DISCUSSION: As shown in Table I, the tested filters had PCEs of 94% or more for endospores. High collection efficiency was also measured for 0.35 /lm PSL particles, with the exception of the 3 /lm PC filter. The PTFE and gelatin filters had PCEs of 95% or more for the MS2 bacteriophage. In contrast, both of the two PC filters had much lower PCEs. Qualitatively, the data are in agreement with the model accounting for the filter collection mechanisms such as impaction, interception, and diffusion. One observation that was found consistently throughout the study was that the gelatin filters became brittle and were difficult to handle after extended sampling.(Clark Burton et al., 2005). CONCLUSIONS: The PTFE filters had the best performance among the tested filters and are expected to be effective for the collection of both B. anthracis and viral particles.
Environmental-exposure; Environmental-hazards; Aerosols; Aerosol-sampling; Aerosol-particles; Laboratory-testing; Filters; Bacteria; Bacterial-cultures; Exposure-levels; Biological-weapons; Biological-warfare-agents; Biological-agents; Biological-effects; Particulates; Models; Sampling; Author Keywords: Bioterrorism; Filters; Collection Efficiency
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Biswas P; Chen DR; Hering S
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Proceedings of the Seventh International Aerosol Conference, September 10-15, 2006, St. Paul, Minnesota
Page last reviewed: June 15, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division