Evaluation of Sampling Probes for Fit Testing N95 Filtering Facepiece Respirators

Abstract

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™ 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.

Revisiting the Improvement of Respiratory System Protection of Mining Workers

“…The direct application of the obtained technical characteristic of respirators in laboratory conditions may result in the errors caused by the influence of various unpredictable factors. The fact is shown in the numerous researches of protective qualities of respirators in the real conditions [3][4][5][6][7][8][9]. The results of the researches may be generalized as follows:…”

Evaluating the risks of occupational respiratory diseases of coal mine workers

“…[3,4]; -in terms of proper selection of a filter and respirator in general, its efficiency is determined by the penetration of unfiltered air through the gaps between facial part of a half-mask (respirator) and a face which is considered to be the main way of the inhaled air contamination [4]; modern filters are characterized by low penetration coefficient (up to 0.01 %) while in terms of half-masks, suction coefficient should be not more than 2 % (under laboratory conditions); -availability of gaps between a half-mask and a face depends upon great amount of factors (face anthropometry, obturator design, headpiece, resistance of filters, head movements, breathing mode, etc. ); they are unsteady being of different shape and dimensions resulting in the fact that a coefficient of protection may change by ten times just within several minutes -that is an inconstant, random, and unpredictable value [5]; -under working conditions, leakage may me more intense than under laboratory ones (e.g. during certification), there is no clear connection between them [6].…”

“…Luigi, is represented in Table 5. Table 6 represents values of suction through possible gaps along the obturation ling of a half-mask being calculated according to (5).…”