Masks block 99.9% of large COVID-linked droplets

Face masks reduce the risk of spreading large COVID-linked droplets when speaking or coughing by up to 99.9 percent, according to a lab experiment with mechanical mannequins and human subjects.

A woman standing two meters (yards) from a coughing man without a mask will be exposed to 10,000 times more such droplets than if he were wearing one, even if he is only 50 centimeters away, they reported in the journal Royal Society Open Science. "There is no more doubt whatsoever that face masks can dramatically reduce the dispersion of potentially virus-laden droplets," senior author Ignazio Maria Viola, an expert in applied fluid dynamics at the University of Edinburgh's School of Engineering, told AFP.

Large respiratory droplets—which act like projectiles before being pulled toward the ground by gravity—are thought to be the main driver of SARS-CoV-2 transmission, he noted. The study focused on particles larger than 170 microns in diameter—roughly two to four times the width of a human hair. Aerosol particles, which tend to follow currents in the air, are generally described as smaller than 20 or 30 microns.

Read more at Phys.org

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