NIOSHTIC-2 Publications Search

Evaluation of sampling probes for fit testing N95 filtering facepiece respirators.

Bergman MS; Viscusi DJ; Zhuang Z; Newcomb WE
Ann Occup Hyg 2013 May; 57(4):507-518
Previous studies have shown a sampling probe bias for measuring fit factors (FFs) in respirator facepieces. This study was conducted to evaluate three sampling probes for fit testing NIOSH-certified N95 filtering facepiece respirators (FFRs). Two phases of fit test experiments were conducted incorporating 'side-by-side' probe mounting: (i) flush probe versus deep probe and (ii) flush probe versus disc probe. Seven test subjects in Phase 1 and six subjects in Phase 2 were fit tested with one to three N95 FFR models for a total of 10 subject/FFR model combinations for each phase. For each experimental condition, induced faceseal leakage (IFSL) through an induced leak was measured using a PORTACOUNT Plus model 8020A Respirator Fit Tester with a model 8095 N95-Companion (TM) accessory. For Phase 1, the mean IFSL of all flush probe measurements (3.6%) was significantly greater than (P < 0.05) the mean IFSL of all deep probe measurements (3.3%). For Phase 2, the mean IFSL of all flush probe measurements (8.5%) was not significantly greater than (P > 0.05) the mean IFSL of all disc probe measurements (8.3%). Results indicate that some leak site and subject/FFR model/leak site combination comparisons (flush probe versus deep probe or flush probe versus disc probe) were statistically different (P < 0.05). The overall mean IFSL for subject/FFR model/leak site combinations differed by 14 and 4% for the flush probe versus deep probe and the flush probe versus disc probe, respectively; however, from a practical standpoint, there is little difference between the flush probe tests compared with the deep probe or disc probe tests. Overall, IFSL measured using the flush probe is higher (resulting in a more conservative measure of faceseal leakage) compared with either the deep probe or disc probe. The more conservative results obtained using the flush probe provide support for its common usage for fit testing cup-shaped FFRs in the USA and potential use for fit testing FFRs in Europe.
Respirators; Respiratory-protective-equipment; Personal-protective-equipment; Performance-capability; Sampling; Sampling-methods; Face-masks; Air-purifying-respirators; Testing-equipment; Measurement-equipment; Laboratory-techniques; Laboratory-testing; Humans; Anthropometry; Leak-detectors; Leak-prevention; Author Keywords: filtering facepiece respirator; fit test; flush probe; N95 respirator; probe bias; respirator probe
Michael S. Bergman, National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, 626 Cochrans Mill Road, Pittsburgh, PA 15236, USA
Publication Date
Document Type
Journal Article
Email Address
Fiscal Year
Identifying No.
Issue of Publication
NIOSH Division
Source Name
Annals of Occupational Hygiene
Page last reviewed: March 25, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division