Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks

As we know, filtration efficiency (FE) is one of the most important concepts when it comes to selecting a High-Efficiency mask. It is a measure of the mask’s ability to protect the user from droplets and aerosols that can penetrate through the filter material. The higher the FE for smaller aerosols, the safer you are. The table below outlines the FEs for different types of mask materials, as well as for hybrid masks (masks made up of 2 different materials). The data is based on the FE for particles sized 0.3 microns or larger. This is because 0.3 microns is the particle size hardest to catch, whereas sizes bigger or smaller than 0.3 microns are easier, depending on the material of the mask. 

 

For more information on the other components of high-efficiency masks, see PPE Selection

Face mask %FFE (SEM) for particles >300nm
N95 (no gap) 99.9 ± 0.1
N95 (with gap) 12 ± 3
surgical mask (no gap) 99.6 ± 0.1
surgical mask (with gap) 44 ± 3
flannel 44 ± 2
cotton (600 TPI), 1 layer 98.4 ± 0.2
chiffon, 1 layer 73 ± 2
natural silk, 1 layer 56 ± 2
hybrid 1: cotton/chiffon 99.2 ± 0.299.6 ± 0.1
hybrid 2: cotton/silk (no gap) 98.5 ± 0.2
hybrid 2: cotton/silk (gap) 32 ± 3
hybrid 3: cotton/flannel 96 ± 1