Table 3. Pore size and cover factor in fabrics in layer I (L1) and layer II (L2) of type II masks.

The mean pore size and cover factor was calculated form ten and five measurements, respectively.

Masks	Layer I pore size (mean ± σ) μm	Cover factor (mean ± σ)	Layer II pore size (mean± σ) μm	Cover factor (mean ± σ)
M13	187 ± 14	87 ± 2	336 ± 21	76 ± 2
M14	245 ± 15	71 ± 2	374 ± 19	68 ± 2
M15	172 ± 16	81 ± 3	723 ± 20	42 ± 6
M16	216 ± 15	83 ± 3	179 ± 38	80 ± 6