Performance of an N95 Filtering Facepiece Particulate Respirator and a Surgical Mask During Human Breathing: Two Pathways for Particle Penetration

Figures & data

FIGURE 1 (A) Experimental setup for testing respirators/masks donned on a human subject; (B) Experimental setup for testing respirators/masks on a manikin equipped with the Breathing Recording and Simulation System.

FIGURE 2 Mean inspiratory flow rates (Q_MIF) recorded with the Breathing Recording and Simulation System for each fit test exercise. Each bar represents the average value of MIF and the standard deviation integrated over 25 subjects of the NIOSH fit testing panel.

FIGURE 3 The exercise-specific breathing patterns recorded by the Breathing Recording and Simulation System from a selected subject exhibiting Q_MIF closest to the average values calculated for 25-subject panel: normal breathing (A), deep breathing (B), head side-to-side (C), head up and down (D), bending over (E).

FIGURE 4 The panel-integrated particle penetration through the N95 facepiece respirator and the surgical mask as a function of particle size. Each point represents the average value and the standard deviation of 75 observations (25 subjects × 3 replicates).

FIGURE 5 The panel-integrated FLTF ratio for the N95 facepiece respirator and the surgical mask. Each point represents the average value and the standard deviation of 75 observations (25 subjects × 3 replicates).

TABLE I Coefficient of Determination, R², of a Simple Linear Regression Between Overall FLTF Ratio and Facial Characteristics

	R^2 Value at a Specific Particle Size
Facial Characteristics	0.05 μm	0.3 μm	1 μm
N95 Respirator
Length (L)	0.0444	0.0437	0.0392
Width (W)	0.0054	0.0007	0.0013
L/W	0.0708	0.0579	0.0560
L×W	0.0072	0.0120	0.0160
Surgical Mask
Length (L)	0.0518	0.1311	0.1635*
Width (W)	0.0518	0.2677*	0.2359*
L/W	0.0176	0.0407	0.0560
L×W	0.1123	0.2773*	0.1879*
Notes: Each cell includes 25 data points, each representing an average of 3 test replicates done for a subject. Statistically significant associations (p < 0.05) are marked with an asterisk.

TABLE II Variability of FLTF Ratios Between Subjects (σ² _B) and Within Subjects (σ² _W)

Particle Size (μm)	σ^2 B	σ^2 W	σ^2 B/(σ^2 B + σ^2 W)
N95 Respirator
0.05	9.92	4.71	0.70
0.3	45.73	22.92	0.67
1	66.81	29.21	0.70
Surgical Mask
0.05	2.98	0.66	0.82
0.3	2.79	0.98	0.74
1	4.21	1.22	0.78

FIGURE 6 The exercise-specific, panel-integrated FLTF ratio for the N95 facepiece respirator and the surgical mask. Each point represents the average value and the standard deviation of 75 observations (25 subjects × 3 replicates).