With much of the public around the world depending on fabric face masks to protect themselves and others, it is essential to understand how the protective ability of fabric masks can be enhanced. This study evaluated the protection offered by eighteen fabric masks designs. In addition, it assessed the benefit of including three design features: insert filters, surgical mask underlayers, and nose wires. Measurements of protective ability were taken by measuring the percentage of sodium (NaCl) particles blocked by fabric face masks. As expected, the fabric masks offered low degrees of protection; however, alterations in design showed significant increase in their protective ability. The most effective designs were multi-layered masks that fit tightly to the face and lacked dead space between the user and mask. Also, low air-resistance insert filters and surgical mask underlays provided the greatest increase in protection.

The data set file 'Fabric Mask Design Data Set.xlsx' contains the fit factor scores obtained by testing a selection of fabric masks. Fit factor scores were generated by a quantitative fit tester, the Portacount 8038+ manufactured by TSI. Activities listed, such as "Normal Breathing" and "Talking", represent the activities undertaken during fit testing as prescribed by OSHA protocol 29CFR1910.134. INDIVIDUAL SHEETS: "Range of Face Mask & Performance" displays the fit factor scores achieved by the fabric masks tested. Photos of these masks can be found in the dataset. "Surgical Underlay" shows fit factors achieved by wearing a fabric mask over a surgical mask. "Filter Size & Type" compares the benefit to fit factor achieved by inserting various filter sizes and types. "Nose Wire" shows the impact of a flexible wire to help mold the top of the mask to the bridge of the nose.