Manikin-Based Performance Evaluation of Elastomeric Respirators Against Combustion Particles

Abstract

This study investigated the effects of faceseal leakage, breathing flow, and combustion material on the overall (non-size-selective) penetration of combustion particles into P-100 half and full facepiece elastomeric respirators used by firefighters. Respirators were tested on a breathing manikin exposed to aerosols produced by combustion of three materials (wood, paper, and plastic) in a room-size exposure chamber. Testing was performed using a single constant flow (inspiratory flow rate = 30 L/min) and three cyclic flows (mean inspiratory flow rates = 30, 85, and 135 L/min). Four sealing conditions (unsealed, nose-only sealed, nose and chin sealed, and fully sealed) were examined to evaluate the respirator faceseal leakage. Total aerosol concentration was measured inside (C(in)) and outside (C(out)) the respirator using a condensation particle counter. The total penetration through the respirator was determined as a ratio of the two (P = C(in) / C(out)). Faceseal leakage, breathing flow type and rate, and combustion material were all significant factors affecting the performance of the half mask and full facepiece respirators. The efficiency of P-100 respirator filters met the NIOSH certification criteria (penetration ≤0.03%); it was not significantly influenced by the challenge aerosol and flow type, which supports the current NIOSH testing procedure using a single challenge aerosol and a constant airflow. However, contrary to the NIOSH total inward leakage (TIL) test protocol assuming that the result is independent on the type of the tested aerosol, this study revealed that the challenge aerosol significantly affects the particle penetration through unsealed and partially sealed half mask respirators. Increasing leak size increased total particle penetration. The findings point to some limitations of the existing TIL test in predicting protection levels offered by half mask elastomeric respirators.

Effects of Breathing Frequency and Flow Rate on the Total Inward Leakage of an Elastomeric Half-Mask Donned on an Advanced Manikin Headform

“…The average size-selective TIL values obtained from this study were comparable to those reported in our previous study with a partially sealed (nose or nose–chin area) half-mask donned on a hard plastic manikin headform (He et al, 2013a,b), and 5- to 10-fold lower than those obtained with the unsealed half-mask donned on the plastic headform. This improvement can be attributed to the softness of the manikin skin, which deforms under stress, thus increasing the contact surface area and consequently forming a better seal.…”

“…An elastomeric 3M 6000 series half-mask respirator equipped with two 3M 2091 P100 filters (3M Corp., St Paul, MN, USA) was chosen for the testing to assure the continuity of our previous research (He et al , 2013a,b). The rationale for selecting the above respirator was described in detail by He et al (2013a).…”

“…Aiming at testing the performance of elastomeric half-mask respirators challenged with combustion aerosols, this study is a follow-up to recent studies (He et al , 2013a,b) conducted in the same laboratory. The present study specifically addresses breathing frequency and flow rate as factors affecting TIL of an elastomeric half-mask respirator.…”

Performance of Electret Filters for Use in a Heating, Ventilation and Air Conditioning System and an Automotive Cabin against Combustion and NaCl Particles

“…At least 95% of the particles were in the size range of 20 to 150 nm. This is also consistent with previous studies (Baxter et al, 2010;He et al, 2013). To ensure sufficient particle number concentrations (especially downstream of the tested filters), the particle size-specific collection efficiency values were determined within a narrower range, 20-150 nm, in 8 channels.…”

A Novel Method for Designing and Fabricating Low-cost Facepiece Prototypes

“…This recommendation is aimed at improving the faceseal for the user, as faceseal leakage is the primary source of contaminant infiltration into a facepiece. (8) To accommodate this recommendation, NIOSH developed digital head form models to correspond to the face size categories of the PCA panel. These new head forms are intended to be more representative of the modern work force as they were developed using three-dimensional data collected from a subset of the anthropometric survey used to develop the panel.…”