Table 3.

Correlation coefficient r and associated p-value between WOB/V_T and breathing resistance at different work rates for inhalation and exhalation by classes of respirators.

Variable	Variable	Correlation coefficient r				p-value for all classes
		Full-facepiece	Half-mask elastomeric	Filtering facepiece	All classes
WOBin/VT Resting	Inhalation resistance	0.84	0.72	0.77	0.26	0.127
WOBin/VT W1		0.81	0.80	0.83	0.71	<0.0001
WOBin/VT W2		0.79	0.83	0.74	0.86	<0.0001
WOBin/VT W3		0.72	0.82	0.46	0.89	<0.0001
WOBin/VT W4		0.80	0.79	0.25	0.90	<0.0001
WOBex/VT Resting	Exhalation resistance	0.66	0.17	0.91	0.79	<0.0001
WOBex/VT W1		0.91	0.80	0.93	0.84	<0.0001
WOBex/VT W2		0.90	0.67	0.92	0.88	<0.0001
WOBex/VT W3		0.81	0.47	0.92	0.73	<0.0001
WOBex/VT W4		0.74	0.54	0.92	0.59	<0.0001