Informing Homemade Emergency Facemask Design: The Ability of Common Fabrics to Filter Ultrafine Particles

Eugenia O'Kelly; Sophia Pirog; James Ward; P John Clarkson

All materials blocked some ultrafine particles (see Figure 1 ). HEPA vacuum bags from Kenmore blocked the most ultrafine particles, with the N95 mask from 3M blocking the second greatest percentage of particles. Other materials, such as the denim jeans and windbreaker blocked a high proportion of ultrafine particles but were very difficult to breathe through (see Figure 2 ) and are thus ill-suited for face mask construction. These materials may be suited to a loose fitting face mask which protects from splashes. When taking into account breathing resistance and filtration efficiency, the most suitable fabrics for face mask construction were thickly felted wool, quilting cotton, and cotton flannel. A single sock held flat also compared well with the above and, when pressed tight against the nose and mouth, is a good emergency substitute for a mask.