Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency

Amy V Mueller; Loretta A Fernandez

A rapid testing protocol is presented for evaluation of loose-fitting type masks to provide information to individuals on particle removal efficacy of masks made with different types of fabrics and with different designs/fits. The protocol collects high-resolution particle count data inside and immediately outside of masks to report both mean and time-based standard deviation of particle removal efficiency. The protocol is validated on N95 masks, and a commercial (3M brand) medical-type masks is used as a baseline for evaluation of alternative mask particle removal efficiencies. The 3M brand mask worn as designed had a mean removal efficiency of 75%; with the exception of the Charcoal Air Pollution facemask and Sewn Mask J, which came close to this removal efficiency, all other masks achieved removal efficiencies of less than 60% when worn as loose-fitting masks. The addition of a nylon stocking overlayer improved the removal efficiency for all loose-fitting masks, including commercial medical-type masks, by 15 to 50 percentage points and also decreased the time-based standard deviation (indicating more consistent All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.