Testing the Effectiveness of Cloth Face Masks
Zangmeister and Vicenzi were part of a team at NIST that analyzed how well 32 natural and synthetic fabrics, including cotton, wool, synthetic, synthetic blends and synthetic/cotton blends, filter particles of a similar size to the coronavirus. Their findings, which were published in the journal ACS Nano last June, determined that three of the five most effective materials at blocking materials were 100% cotton with visible raised fibers or nap, such as that found in flannels. Meanwhile, four of the five lowest performers were synthetics.
To analyze the effectiveness of the fabrics, the team tested swatches (not complete masks) and flowed a stream of particles through it. They then counted the number of particles in the air before and after it passed through the fabric. They did not use real samples of the coronavirus in their experiment, as they are dangerous, and instead used salt as their “stand-in” particles, which is the substance recommended in these situations by the National Institute for Occupational Safety and Health.
