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

Amy V Mueller; Loretta A Fernandez

The effectiveness of cloth masks to protect wearers from airborne particles, when studied previously, has been shown to be a function of both materials and fit. Anticipating the need to produce face coverings from readily-available materials, several studies used standard methods for materials testing to compare the filtration efficiency of materials such as cotton t-shirts, sweatshirts, handkerchiefs, and towels with the filtration efficiency of facepiece respirators (N95 masks) and surgical masks (Cooper et al. 1983a; OSHA 1998; van der Sande et al. 2008; Rengasamy et al. 2010; ASTM 2017b; a; 2019a; b) . While none of these materials produced filtration efficiency close to respirators such as N95s, cotton cloth facemasks were found to provide about half the protection of standard surgical masks against airborne particles (van der Sande et al. 2008) , while an elastic layer (e.g., nylon stocking) placed over the mask material was found to improve filtration efficiency of loose-fitting masks by minimizing air flow around the cloth layers (Cooper et al. 1983b ).