COVID-19: Most Efficacious Face Masks /NEW ENGLAND JOURNAL OF MEDICINE
By Amy Orciari Herman
Edited by André Sofair, MD, MPH
Most efficacious face masks: N95, surgical, polypropylene, and handmade cotton face masks all appear efficacious for blocking respiratory droplets, while bandanas and fleeces seem to offer little protection, according to a study in Science Advances. Researchers tested the efficacy of 14 different mask types as follows: A male wearing each mask repeatedly spoke the words "Stay healthy, people" toward a laser beam inside a dark box. Droplets that passed through the laser scattered light, which was recorded with a cell phone camera, and a computer program then counted the droplets in the video. For reference, the speaker did the same while not wearing a mask. N95 masks were most efficacious, followed by surgical masks, then polypropylene masks and handmade cotton face coverings. Other masks were less efficacious. In particular, gaiter-type fleece coverings seemed to spread larger respiratory droplets into numerous smaller droplets. Of this, the researchers write, "Considering that smaller particles are airborne longer than large droplets ... the use of such a mask might be counterproductive."
FROM SCIENCE ADVANCES
