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Table 3 Comparison of the filtration performance of masks made of different materials [16]

From: Addressing the worldwide shortages of face masks

Sample Flow rate: 1.2 CFM
Filter efficiency (%) Pressure differential
< 300 nm average ± error > 300 nm average ± error ΔP (Pa)
N 95 85 ± 15 99.9 ± 0.1 2.2
Surgical mask 76 ± 22 99.6 ± 0.1 2.2
Cotton quilt 96 ± 2 96.1 ± 0.3 2.7
Quilter’s cotton (80TPI), 1 layer 9 ± 13 14 ± 1 2.2
Quilter’s cotton (80TPI), 2 layers 38 ± 11 49 ± 3 2.5
flannel 57 ± 8 44 ± 2 2.2
Cotton (600TPI), 1 layer 79 ± 23 98.4 ± 0.2 2.5
Cotton (600TPI), 2 layers 82 ± 19 99.5 ± 0.1 2.5
Chiffon, 1 layer 67 ± 16 73 ± 2 2.7
Chiffon, 2 layers 83 ± 9 90 ± 1 3.0
Natural silk, 1 layer 54 ± 8 56 ± 2 2.5
Natural silk, 2 layers 65 ± 10 65 ± 2 2.7
Natural silk, 4 layers 86 ± 5 88 ± 1 2.7
Cotton/chiffon 97 ± 2 99.2 ± 0.2 3.0
Cotton/silk 94 ± 2 98.5 ± 0.2 3.0
Cotton/flannel 95 ± 2 96 ± 1 3.0
  1. TPI = Threads per inch