Relationship of sampling efficiency for manikin-mounted personal samplers to efficiency measurements made independent of manikin

Smith, Jerome P.; Bird, Aaron J.

doi:10.1016/s0021-8502(02)00068-x

Cited by 7 publications

(9 citation statements)

References 38 publications

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“…Smith and Bird (2002) found that velocity was decreased and reached a minimum in the chest region, but in the face region there was less deceleration of velocity. Topp et al (2003) also noted velocity increases in the chest region but not as large increases in the head region.…”

Section: Discussionmentioning

confidence: 93%

“…One study found that the use of a simplified torso (fashioned from a wastebasket) resulted in aspiration efficiencies 35% that of the samplers placed on a human-shaped mannequin with torso truncation (Kennedy et al, 2001). Sampler studies conducted by Smith and Bird (2002) identified a decrease in vertical velocity in the chest region, with a smaller decrease in the facial region using a full-sized, tailor's mannequin, again truncated at the waist. However, like the thermal studies, these investigations lacked inhalation at the mouth, so the influence of these flow differences near an inhaling mannequin is unknown.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Anderson

Anthony

2012

The Annals of Occupational Hygiene

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Computational fluid dynamics (CFD) has been used to report particle inhalability in low velocity freestreams, where realistic faces but simplified, truncated, and cylindrical human torsos were used. When compared to wind tunnel velocity studies, the truncated models were found to underestimate the air's upward velocity near the humans, raising questions about aspiration estimation. This work compares aspiration efficiencies for particles ranging from 7 to 116 µm using three torso geometries: (i) a simplified truncated cylinder, (ii) a non-truncated cylinder, and (iii) an anthropometrically realistic humanoid body. The primary aim of this work is to (i) quantify the errors introduced by using a simplified geometry and (ii) determine the required level of detail to adequately represent a human form in CFD studies of aspiration efficiency. Fluid simulations used the standard k-epsilon turbulence models, with freestream velocities at 0.1, 0.2, and 0.4 m s −1 and breathing velocities at 1.81 and 12.11 m s −1 to represent at-rest and heavy breathing rates, respectively. Laminar particle trajectory simulations were used to determine the upstream area, also known as the critical area, where particles would be inhaled. These areas were used to compute aspiration efficiencies for facing the wind. Significant differences were found in both vertical velocity estimates and the location of the critical area between the three models. However, differences in aspiration efficiencies between the three forms were <8.8% over all particle sizes, indicating that there is little difference in aspiration efficiency between torso models.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Anderson

Anthony

2012

The Annals of Occupational Hygiene

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“…Turbulence intensity at the inlets and within the sampler, provided it is less than about 10%, should have little effect on the sampling efficiency for aerosol particles with Stokes numbers less than 1 (Vincent et al 1985;Wiener et al 1988), which is the case for these simulations. Turbulence intensity in the simulations was maintained at 5% at the inflow of the computational domain, and 3% inside the sampler based on experimental values of similar flows (Smith and Bird 2002). The range of potential length scales was defined by estimates of the Kolmogorov microscales and experimental values (Vincent et al 1985).…”

Section: Boundary and Operating Conditionsmentioning

confidence: 99%

Use of Numerical Calculations to Simulate the Sampling Efficiency Performance of a Personal Aerosol Sampler

Bird

2005

Aerosol Science and Technology

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Numerical calculations were conducted to simulate air and particle behavior near and into the inlet of an aerosol sampler in order to determine sampling efficiency performance. This was done with the pre-verified commercial computational fluid dynamics (CFD) software package, FLUENT (Fluent, Inc., Lebanon, NH, US). Air flow behavior was calculated for steady-state conditions approaching and flowing into 3D geometries of an aerosol sampler free in the air that was similar in dimension to two commercial samplers, namely the Gesamtstaubprobenahme sampler (GSP) and the conical inhalable sampler (CIS). Particle trajectories were calculated in a Lagrangian reference frame on the resulting velocity fields. Based on the particle trajectories, sampling efficiencies were calculated and compared to those reported in the literature for a CIS aerosol sampler. They were found to have similar overall trends for particle sizes up to 21 µm. Using a correction factor, agreement The findings and conclusions in this report are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institute for Occupational Safety and Health. Mention of a commercial product or trade name does not constitute endorsement by the Centers for Disease Control and Prevention or the National Institute for Occupational Safety and Health.Address correspondence to Aaron J. Bird, M/S 3030, Exposure Assessment Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1095 Willowdale Road, Morgantown, West Virginia 26505, USA. E-mail: ABird@cdc.gov was observed to be very good for smaller particles, but less so for larger particles.

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“…In order to compare the sampling efficiency of the different coating materials with a standard method the GSP 3.5 filter system with fibrous cellulose nitrate filters was used which is well investigated and recommended as reference system by various authors (Spaan et al 2006;Predicala and Mahhirang 2003;Witschger et al 1998;Smith and Bird 2002;Kenny et al 1997). The cellulose nitrate filters gained wide acceptance as collection surface because they appeared to have reduced particle bounce (Hu 1971;Rao and Whitby 1978;Sahu et al 2005).…”

Section: Reference Filter Systemmentioning

confidence: 99%

Effective Collection of Airborne Micro-Organisms by Direct Impaction on Silicone Sealants—Comparison of Different Adherent Surfaces

Clauß¹,

Springorum²,

Hartung³

2010

Aerosol Science and Technology

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For effective sampling of airborne micro-organisms different techniques such as impingement, filtration and impaction are commonly used. Impaction is the method which allows best for direct collection on adhesive surfaces for immediate microscopic analysis. The efficiency of collection largely depends on the quality of the sampling surface to retain particles. This article compares the suitability of some traditional and new adhesive coatings to collect and retain airborne micro-organisms efficiently for subsequent fluorescence microscopy. Sacharomyces cerevisiae yeast cells were aerosolized in a test tubing system in the laboratory. Samples were collected by a round jet impactor in a defined round deposition area on glass slides coated with different adhesive materials. Particle distribution in the deposition area and collection efficiency as well as particle losses were estimated. Fluorescent staining with Mycoval and DAPI was used to quantify the amount of collected cells and cell losses due to the staining procedure. Filtration was taken as reference system. The collection efficiency of the tested adhesive surfaces ranged from 2 to 97%. Silicone sealants showed with 97% the highest collection efficiency. All particles were located in the central region of the deposition area. Cell losses due to the staining procedure were very small (<1%) and no background fluorescence was observed after DAPI staining. Even after sampling times of 45 min the collection efficiency was still above 90%. Longer collection (>50 min) resulted in increasing cell losses. Collection efficiency was little influenced by relative humidity of the air between 20% and 100%.

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Relationship of sampling efficiency for manikin-mounted personal samplers to efficiency measurements made independent of manikin

Cited by 7 publications

References 38 publications

Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Use of Numerical Calculations to Simulate the Sampling Efficiency Performance of a Personal Aerosol Sampler

Effective Collection of Airborne Micro-Organisms by Direct Impaction on Silicone Sealants—Comparison of Different Adherent Surfaces

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