Study on the relationship between the fitness of three types of N95 respirators and facial dimensions

Figures & data

Table 1. The definition of face parameters.

Parameters	Definition
Face length	Vertical distance from the midpoint of two eyes to the midpoint of the chin
Face width	Face width in the cheekbone plane
Jaw length	Length from the lower lip to the midpoint of the chin
Jaw width	Width of the chin in the plane of the mandibular angle
Nose length	Distance from root to tip of the nose
Nose width	The width of the widest part of the nose
Profile face width	Distance from ear to face plane
Mouth Width	Distance between two corners of the mouth

Table 2. Sequence of exercises performed in fit testing.

Exercises (duration)	Method
Normal breathing (60 s)	Sit normally and breathe as usual
Deep breathing (60 s)	Sit normally and take long, deep breaths
Side-to-side head movement (60 s)	Breathe normally and slowly turn the head to the left and right sides with a short stay at the extreme position of each side Repeat the action until the end of this step
Up-and-down head movement (60 s)	Breathe normally and slowly raise your head until you can see the roof, and then lower your head until you can see the ground Repeat the action until the end of this step
Talking (60 s)	Sit normally and read a prepared paragraph aloud, it could be heard clearly at a distance of 5 m
Normal breathing (60 s)	Sit normally and breathe as usual

Table 3. Basic characteristics of participants.

Characteristics	Male (mean (SD))	Female (mean (SD))
Age (years)	37.32 (10.16)	36.61 (10.74)
Height (cm)	174.21 (6.13)	161.72 (4.68)
Weight (kg)	74.86 (12.06)	59.29 (10.57)
BMI (kg/m^2)	24.63 (3.42)	22.65 (3.85)

Table 4. Summary of comparison results of facial dimensions between the "pass" and "fail" groups (independent sample t-test).

N95 (style)	Facial dimensions *Indicates a statistically significant difference.	Pass (cm) (mean (SD))	Fail (cm) (mean (SD))	p-value
3M 9132 (Folding)	face length	11.34 (0.35)	11.31 (0.31)	0.53
	face width	9.79 (0.07)	9.78 (0.06)	0.28
	chin length	4.10 (0.10)	4.1 (0.09)	0.46
	chin width	7.43 (0.14)	7.44 (0.13)	0.69
	*nose length	4.65 (0.08)	4.62 (0.08)	<0.01
	nose width	3.32 (0.07)	3.32 (0.06)	0.53
	*nose height	2.04 (0.05)	2.02 (0.05)	0.05
	profile face length	10.68 (0.15)	10.67 (0.15)	0.40
	mouth width	5.62 (0.26)	5.64 (0.25)	0.54
NTPN95N (Flat)	face length	11.31 (0.32)	11.33 (0.33)	0.63
	face width	9.78 (0.06)	9.78 (0.07)	0.87
	*chin length	4.11 (0.09)	4.08 (0.09)	<0.01
	chin width	7.45 (0.13)	7.43 (0.13)	0.28
	nose length	4.63 (0.08)	4.62 (0.08)	0.66
	*nose width	3.33 (0.07)	3.31 (0.06)	0.04
	nose height	2.03 (0.05)	2.02 (0.05)	0.30
	profile face length	10.68 (0.15)	10.66 (0.15)	0.11
	mouth width	5.64 (0.26)	5.64 (0.25)	0.81
WN-N95 (Arched)	face length	11.31 (0.31)	11.34 (0.34)	0.37
	face width (mean (SD))	9.79 (0.06)	9.78 (0.07)	0.23
	chin length (mean (SD))	4.10 (0.09)	4.10 (0.09)	0.66
	chin width (mean (SD))	7.43 (0.13)	7.45 (0.13)	0.20
	nose length (mean (SD))	4.63 (0.08)	4.62 (0.08)	0.10
	nose width (mean (SD))	3.32 (0.06)	3.32 (0.07)	0.75
	nose height (mean (SD))	2.03 (0.05)	2.03 (0.05)	0.54
	profile face length (mean (SD))	10.67 (0.14)	10.68 (0.16)	0.45
	mouth width (mean (SD))	5.62 (0.27)	5.66 (0.23)	0.28

Table 5. Summary of Spearman’s rank correlation coefficients of FF values and face dimensions.

N95 (style)	Facial dimensions *Indicates statistical significance.	Spearman’s rank correlation coefficient	p-value
3M 9132 (Folding)	face length	0.01	0.82
	*face width	0.12	0.03
	chin length	0.06	0.27
	chin width	0.05	0.38
	*nose length	0.13	0.02
	nose width	0.10	0.08
	*nose height	0.14	0.02
	profile face length	0.03	0.59
	mouth width	−0.01	0.92
NTPN95N (Flat)	face length	0.00	0.99
	face width	−0.04	0.45
	*chin length	0.18	<0.01
	chin width	0.08	0.15
	nose length	0.01	0.88
	*nose width	0.16	<0.01
	nose height	0.06	0.33
	*profile face length	0.13	0.02
	mouth width	−0.00	0.95
WN-N95 (Arched)	face length	−0.03	0.65
	face width	0.07	0.23
	chin length	0.02	0.75
	chin width	−0.02	0.71
	*nose length	0.13	0.03
	nose width	0.01	0.89
	nose height	0.09	0.13
	profile face length	−0.03	0.66
	mouth width	−0.09	0.12