Improvement in Fitted Filtration Efficiency of N95 Respirators With Escalating Instruction of the Wearer

Abstract

Introduction: Fitted filtration performance of an N95 respirator may benefit from differing levels of instructions.

Methods: Using a modified Occupational Safety and Health Administration fit test protocol, we measured fitted filtration efficiency for an N95 respirator in 21 screened, healthy participants given 4 levels of escalating instruction: (1) uninstructed (baseline), (2) written/pictorial manufacturer instructions, (3) step-by-step video demonstration, and (4) staff instruction (visual inspection of respirator fit and verbal suggestions to adjust when applicable).

Results: Baseline fitted filtration efficiency was not significantly different between participants with or without previous experience of N95 use. Clear improvements in fitted filtration efficiency were observed progressing from baseline (average=86.1%) to manufacturer paper instructions (93.3%), video instructions (97.5%), and post staff intervention (98.3%). Baseline fitted filtration efficiency values were significantly lower than those after video instruction (p<0.037) and staff intervention (p<0.033) sessions.

Conclusions: Beyond uninstructed wear or provision of manufacturer instructions, efforts to train and instruct users in proper respirator fit principles with visual feedback are likely to yield benefits to public health outcomes in reducing respiratory exposure during air quality emergencies such as airborne viral outbreaks and wildland fires.

Figure 1

FFE (calculated as (100 × [1‒mask/ambient] particle counts) percentages are shown for each participant across escalating instruction conditions (baseline, paper [manufacturer] instruction, video instruction, and staff-recommended intervention). The mean and 95% CI calculated for each condition are shown with blue lines. *=significant difference (p<0.05) from baseline in a linear mixed effect model with subject as a random factor. Paper (#) shows the laminated copy of text and pictorial instructional content from 3M 9200 Series package insert. Video (%) features a U.S. Public Health Officer demonstrating the process of putting on an N95 with audio narration and on-screen text and graphics to reinforce key concepts are shown. Participants could pause and rewind the video as desired to review specific steps or instructions. Each data point summarizes the average performance of a participant who performed the modified OSHA fit test exercises. Anonymized individual participant results are provided as supplementary material. FFE, fitted filtration efficiency.

Figure 2

Exercise-specific FFE percentages shown separately for the top (blue) and bottom (orange) 5 performers from the baseline test. FFE is plotted for these groups per exercise starting from (along x-axis) baseline and progressing across the escalating levels of instruction. Panels correspond to (A) bending at the waist, (B) reading the rainbow passage, (C) moving head side to side, and (D) moving head up and down. Exercises B, C, and D were 30 seconds in duration, whereas A was 50 seconds for a total of about 3 minutes per complete OSHA test per instruction condition. FFE, fitted filtration efficiency.