Document Detail

Penetration of fiber versus spherical particles through filter media and faceseal leakage of n95 filtering facepiece respirators with cyclic flow.
MedLine Citation:
PMID:  23339437     Owner:  NLM     Status:  In-Data-Review    
This study investigated differences in penetration between fibers and spherical particles through faceseal leakage of an N95 filtering facepiece respirator. Three cyclic breathing flows were generated corresponding to mean inspiratory flow rates (MIF) of 15, 30, and 85 L/min. Fibers had a mean diameter of 1 μm and a median length of 4.9 μm (calculated aerodynamic diameter, d(ae) = 1.73 μm). Monodisperse polystyrene spheres with a mean physical diameter of 1.01 μm (PSI) and 1.54 μm (PSII) were used for comparison (calculated d(ae) = 1.05 and 1.58 μm, respectively). Two optical particle counters simultaneously determined concentrations inside and outside the respirator. Geometric means (GMs) for filter penetration of the fibers were 0.06, 0.09, and 0.08% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.07, 0.12, and 0.12%. GMs for faceseal penetration of fibers were 0.40, 0.14, and 0.09% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.96, 0.41, and 0.17%. Faceseal penetration decreased with increased breathing rate for both types of particles (p ≤ 0.001). GMs of filter and faceseal penetration of PSII at an MIF of 30 L/min were 0.14% and 0.36%, respectively. Filter penetration and faceseal penetration of fibers were significantly lower than those of PSI (p < 0.001) and PSII (p < 0.003). This confirmed that higher penetration of PSI was not due to slightly smaller aerodynamic diameter, indicating that the shape of fibers rather than their calculated mean aerodynamic diameter is a prevailing factor on deposition mechanisms through the tested respirator. In conclusion, faceseal penetration of fibers and spherical particles decreased with increasing breathing rate, which can be explained by increased capture by impaction. Spherical particles had 2.0-2.8 times higher penetration through faceseal leaks and 1.1-1.5 higher penetration through filter media than fibers, which can be attributed to differences in interception losses.
Kyungmin Jacob Cho; Leonid Turkevich; Matthew Miller; Roy McKay; Sergey A Grinshpun; Kwonchul Ha; Tiina Reponen
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of occupational and environmental hygiene     Volume:  10     ISSN:  1545-9632     ISO Abbreviation:  J Occup Environ Hyg     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-01-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101189458     Medline TA:  J Occup Environ Hyg     Country:  England    
Other Details:
Languages:  eng     Pagination:  109-15     Citation Subset:  IM    
a Department of Environmental Health , University of Cincinnati , Cincinnati , Ohio.
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