TY - JOUR
T1 - Investigation of cut-off sizes and collection efficiencies of portable microbial samplers
AU - Yao, Maosheng
AU - Mainelis, Gediminas
N1 - Funding Information: This research was supported by CDC/NIOSH grant DHHS-CDC1-K01-OH008029. The authors are thankful for the support. The technical assistance by EMD Chemicals, Inc. (Gibbstown, NJ), A.P. BUCK Inc. (Orlando, FL), Veltek Associates, Inc. (Phoenixville, PA), Bioscience International, Inc. (Rockville, MD), Millipore Corp. (Billerica, MA), and Biotest Diagnostics Corp. (Denville, NJ) is appreciated.
PY - 2006/6/1
Y1 - 2006/6/1
N2 - This research investigated the physical collection efficiencies and cut-off sizes of SMA MicroPortable, BioCulture, Microflow, Microbiological Air Sampler (MAS-100), Millipore Air Tester (MAT), SAS Super 180, and RCS High Flow portable microbial samplers when collecting Polystyrene Latex particles ranging from 0.5 to 9.8 μm in aerodynamic size. Traditional collection efficiency measurements often directly compare particle concentrations upstream and downstream of the sampler without considering the particle losses. Here, we developed a new approach which tests collection efficiencies of the sampler with and without agar collection plate loaded. This method thus allows estimating the effective collection efficiency, i.e., the fraction of incoming particles deposited onto the agar collection medium only. The experimental cut-off sizes, or d50 , of the investigated samplers ranged from 1.2 μm for the RCS High Flow, 1.7 μm for the MAS-100, 2.1 μm for SAS Super 180, to 2.3 μm for MAT; for other three samplers they were close to or above 5 μm. In most cases the theoretical d50 was lower than the experimental value, which was likely due to the dissipation of impactor jets and the influence of cross-flow in the multi-nozzle impactors. For most samplers, we observed a notable difference between the collection efficiency obtained by the traditional measurement method and the effective collection efficiency. In general, all samplers collected 10% or less of 0.5 μm particles onto the agar medium. This study indicates that the use of most of the tested bioaerosol samplers may result in a substantial underestimation of bacterial concentrations, especially of single bacterial cells with diameter 0.5-1.0 μm. On the other hand, most of the investigated samplers would be more efficient when collecting larger fungal spores.
AB - This research investigated the physical collection efficiencies and cut-off sizes of SMA MicroPortable, BioCulture, Microflow, Microbiological Air Sampler (MAS-100), Millipore Air Tester (MAT), SAS Super 180, and RCS High Flow portable microbial samplers when collecting Polystyrene Latex particles ranging from 0.5 to 9.8 μm in aerodynamic size. Traditional collection efficiency measurements often directly compare particle concentrations upstream and downstream of the sampler without considering the particle losses. Here, we developed a new approach which tests collection efficiencies of the sampler with and without agar collection plate loaded. This method thus allows estimating the effective collection efficiency, i.e., the fraction of incoming particles deposited onto the agar collection medium only. The experimental cut-off sizes, or d50 , of the investigated samplers ranged from 1.2 μm for the RCS High Flow, 1.7 μm for the MAS-100, 2.1 μm for SAS Super 180, to 2.3 μm for MAT; for other three samplers they were close to or above 5 μm. In most cases the theoretical d50 was lower than the experimental value, which was likely due to the dissipation of impactor jets and the influence of cross-flow in the multi-nozzle impactors. For most samplers, we observed a notable difference between the collection efficiency obtained by the traditional measurement method and the effective collection efficiency. In general, all samplers collected 10% or less of 0.5 μm particles onto the agar medium. This study indicates that the use of most of the tested bioaerosol samplers may result in a substantial underestimation of bacterial concentrations, especially of single bacterial cells with diameter 0.5-1.0 μm. On the other hand, most of the investigated samplers would be more efficient when collecting larger fungal spores.
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U2 - 10.1080/02786820600729146
DO - 10.1080/02786820600729146
M3 - Article
SN - 0278-6826
VL - 40
SP - 595
EP - 606
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
IS - 8
ER -