Distribution of Faceseal Leak Sites on a Half-Mask Respirator and Their Association with Facial Dimensions

Oestenstad, Riedar K.; Dillion, H. Kenneth; Perkins, Laura

doi:10.1202/0002-8894(1990)051<0285:doflso>2.0.co;2

Cited by 16 publications

(22 citation statements)

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“…2). Face seal leak distributions for FFR utilizing an IRC during fit testing have not been previously reported, but the 26.5% incidence for nasal region leaks in the current study compares favorably with the 32.9% and 36.7% incidences reported in two previous studies addressing leaks in subjects wearing elastomeric half‐mask respirators [Oestenstad et al, 1990; Oestenstad and Bartolucci, 2010]. The nasal region as a major contributor to FFR leakage is recognized [Health and Safety Executive, 2009] and not surprising given its bony prominence and thin skin covering, as well as the variability of nasal features based on such issues as ethnicity, gender, prior trauma, surgery, etc., coupled with the variability in available FFR features (e.g., pliable nose bars, pre‐molded nasal contours, internal flanges, etc.).…”

Section: Discussionsupporting

confidence: 67%

Infrared imaging for leak detection of N95 filtering facepiece respirators: A pilot study

Roberge

Monaghan

Palmiero³

et al. 2011

American J Industrial Med

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Section: Discussionsupporting

confidence: 67%

Infrared imaging for leak detection of N95 filtering facepiece respirators: A pilot study

Roberge

Monaghan

Palmiero³

et al. 2011

American J Industrial Med

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“…The location of faceseal leak sites on a half-mask respirator by the deposition of a fluorescent tracer aerosol during a standard quantitative fit test was observed by Oestenstad et al (1990). The results of this study indicated that faceseal leaks at the nose and chin were of the greatest importance for the half-mask respirator.…”

Section: Revlew Of Previous Workmentioning

confidence: 66%

“…In these models, the flow rate through the leak hole was predicted by the equation, QL = K(AP)"(Do)~, where QL is the flow rate through the leak hole, K, a, and b are constants, A P is the pressure drop across the respirator filter, and Do is the diame- Oestenstad et al (1990) 0.5-1.0~ 2.70 aConstant a ranges from 0.962 for the 0.5-mm leak hole to 0.562 for the 3.2-mm leak hole.…”

Section: Revlew Of Previous Workmentioning

confidence: 99%

Respirator Leak Detection by Ultrafine Aerosols: A Predictive Model and Experimental Study

Liu

Lee

Mullins³

et al. 1993

Aerosol Science and Technology

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The leak performance of half-mask, maintenance-free respirators was studied theoretically and experimentally. A predictive model for the theoretical protection factor and leakage flow has been developed that uses the equation of particle conservation inside and outside the respirator. An experimental study was conducted using NaCl particles of 10 nm in diameter and a condensation nucleus counter as the particle detector. A respirator fitted with controlled leak holes of 20-3000 p m in diameter was tested at steady flow rates of 10, 32, and 100 L/min. Results showed that the aerosol penetration into a respirator was strongly influenced by the filter efficiency, leak hole size, and flow rate through the respirator. The results are in good agreement with theory, but some discrepancy bas been noted at lower flow rates and smaller leak hole sizes. For the dnst/mist respirators, the experimental protection factor for ultrafine 0.01-pm NaCl particles ranged from 3145 to as low as 3. For the high efficiency dust/mist/ fume/radionuclide respirator, a protection factor as high as 4.1 X lo9 was measured on the ultrafine aerosol. For all respirators, the protection factors decreased rapidly with increasing leak hole size and increased as flow rate decreased.The result of the study shows that with ultrafine aerosols, the particle penetration through the respirator filter can be reduced to a small, and in some instances, negligible value. The resulting protection factor is then due almost entirely to aerosol penetration through the leak hole. The ultrafine aerosol test can thus be used to study the characteristics of the face seal leakage, without the complication of the aerosol penetration through the respirator filter.

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“…Tel: 806-742-3563 (extension 229); fax: 806-742-3540; e-mail: james.yang@ttu.edu facepiece leak locations. Oestenstad et al (1990Oestenstad et al ( , 2010 used facial deposition of a fluorescent tracer and black light visualization to photograph leak location and shape on subjects wearing half-mask respirators. They found that facial dimensions were significantly associated with leak location, while gender and respirator size showed a weaker association.…”

Section: Introductionmentioning

confidence: 99%

“…Faceseal leakage of an FFR can be significantly impacted by facial dimensions, breathing intensity, and activity (Han and Lee, 2005 ;Lee et al, 2005;Grinshpun et al, 2009;Oestenstad et al, 1990Oestenstad et al, , 2010. Facial features affect the flow field near the nose or mouth of a breathing human (Anthony et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Simulation and Evaluation of Respirator Faceseal Leaks Using Computational Fluid Dynamics and Infrared Imaging

Lei

Yang

Zhuang

et al. 2012

The Annals of Occupational Hygiene

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This paper presents a computational fluid dynamics (CFD) simulation approach for the prediction of leakage between an N95 filtering facepiece respirator (FFR) and a headform and an infrared camera (IRC) method for validating the CFD approach. The CFD method was used to calculate leak location(s) and 'filter-to-faceseal leakage' (FTFL) ratio for 10 headforms and 6 FFRs.The computational geometry and leak gaps were determined from analysis of the contact simulation results between each headform-N95 FFR combination. The volumetric mesh was formed using a mesh generation method developed by the authors. The breathing cycle was described as a time-dependent profile of the air velocity through the nostril. Breathing air passes through both the FFR filter medium and the leak gaps. These leak gaps are the areas failing to achieve a seal around the circumference of the FFR. The CFD approach was validated by comparing facial temperatures and leak sites from IRC measurements with eight human subjects. Most leaks appear at the regions of the nose (40%) and right (26%) and left cheek (26%) sites. The results also showed that, with N95 FFR (no exhalation valves) use, there was an increase in the skin temperature at the region near the lip, which may be related to thermal discomfort. The breathing velocity and the viscous resistance coefficient of the FFR filter medium directly impacted the FTFL ratio, while the freestream flow did not show any impact on the FTFL ratio. The proposed CFD approach is a promising alternative method to study FFR leakage if limitations can be overcome.

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Distribution of Faceseal Leak Sites on a Half-Mask Respirator and Their Association with Facial Dimensions

Cited by 16 publications

References 0 publications

Infrared imaging for leak detection of N95 filtering facepiece respirators: A pilot study

Infrared imaging for leak detection of N95 filtering facepiece respirators: A pilot study

Respirator Leak Detection by Ultrafine Aerosols: A Predictive Model and Experimental Study

Simulation and Evaluation of Respirator Faceseal Leaks Using Computational Fluid Dynamics and Infrared Imaging

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