Table 4. Test results of particle filtration efficiency of materials for single-layer homemade masks with qualified pressure difference.

Material	$\stackrel{-}{\mathit{X}}\pm \mathit{S}\mathit{D}$	t/T value	P value	Qualified or Not
T-shirt	12%±1%	-34.516	<0.001	No
Fleece sweater	6% c	0.000	0.017	No
Hairy tea towel	23%±1%	-121.000	<0.001	No
Granular tea towel	12%±1%	-13.880	<0.001	No
Non-woven shopping bag	14%±2%	-56.921	<0.001	No
Pillowcase C	0%±0%	-19.124	<0.001	No
Medical non-woven fabric	42%±2%	17.789	1.000	Yes
Medical gauze (4 layers)	2% c	0.000	0.019	No
Medical gauze (8 layers)	3% c	0.000	0.019	No
Medical gauze (12 layers)	6% c	0.000	0.019	No
Medical gauze (16 layers)	14%±1%	-24.422	<0.001	No

^c Median.