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Large Particle Penetration through N95 Respirator Filters and Facepiece Leaks with Cyclic Flow

2009; Oxford University Press; Linguagem: Inglês

10.1093/annhyg/mep062

1475-3162

Kyungmin Jacob Cho, Tiina Reponen, Roy T. McKay, Rakesh Shukla, Hiroki Haruta, Padmini Sekar, Sergey A. Grinshpun,

Burn Injury Management and Outcomes

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 μm). 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.