title: Large particle penetration through N95 respirator filters and facepiece leaks with cyclic flow.
abstract: The aim of this study was to investigate respirator filter and faceseal penetration of particles representing bacterial and fungal spore size ranges (0.7-4 mum). First, field experiments were conducted to determine workplace protection factors (WPFs) for a typical N95 filtering facepiece respirator (FFR). These data (average WPF = 515) were then used to position the FFR on a manikin to simulate realistic donning conditions for laboratory experiments. Filter penetration was also measured after the FFR was fully sealed on the manikin face. This value was deducted from the total penetration (obtained from tests with the partially sealed FFR) to determine the faceseal penetration. All manikin experiments were repeated using three sinusoidal breathing flow patterns corresponding to mean inspiratory flow rates of 15, 30, and 85 l min(-1). The faceseal penetration varied from 0.1 to 1.1% and decreased with increasing particle size (P < 0.001) and breathing rate (P < 0.001). The fractions of aerosols penetrating through the faceseal leakage varied from 0.66 to 0.94. In conclusion, even for a well-fitting FFR respirator, most particle penetration occurs through faceseal leakage, which varies with breathing flow rate and particle size.
authors.affiliation: Center for Health-Related Aerosol Studies, University of Cincinnati, Cincinnati, OH 45267, USA.
authors.forename: Kyungmin Jacob
authors.initials: KJ
authors.lastname: Cho
authors.forename: Tiina
authors.initials: T
authors.lastname: Reponen
authors.forename: Roy
authors.initials: R
authors.lastname: McKay
authors.forename: Rakesh
authors.initials: R
authors.lastname: Shukla
authors.forename: Hiroki
authors.initials: H
authors.lastname: Haruta
authors.forename: Padmini
authors.initials: P
authors.lastname: Sekar
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Grinshpun
mesh_terms: D000328:Adult; D000336:Aerosols / Q000032:analysis; D000383:Agriculture; D000395:Air Pollutants, Occupational / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D019570:Inhalation Exposure / Q000517:prevention & control; D008348:Manikins; D008422:Materials Testing; D016273:Occupational Exposure / Q000517:prevention & control; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis; D010865:Pilot Projects; D012134:Respiratory Protective Devices; D056152:Respiratory Rate
chemical_list: D000336:Aerosols; D000395:Air Pollutants, Occupational; D052638:Particulate Matter
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