Plastic face shields are all but useless when it comes to defeating the spread of the coronavirus, according to a new Japanese study.
The clear coverings were tested in a simulation by Fugaku, the world’s fastest supercomputer, which found that nearly 100% of airborne droplets less than 5 micrometers in size escaped through the shields, the Guardian reported Tuesday.
One micrometer is the equivalent of one-millionth of a meter.
The shields, typically used by workers in the restaurant industry, were also ineffective at trapping larger droplets measuring 50 micrometers — about half of which were also able to escape.
The study was conducted by Riken, a government-backed researcher center in Kobe, Japan.
In order to reach its results, the Fugaku simulation combined airflow with thousands of particles of various sizes.
Makoto Tsubokura, a team leader at Riken, said regular face masks should be used instead of face shields.
“Judging from the results of the simulation, unfortunately the effectiveness of face guards in preventing droplets from spreading from an infected person’s mouth is limited compared with masks,” he told the Guardian.
Tsubokura said people who are not recommended to wear face masks could resort to donning shields — but only if they were outdoors or in indoor settings with proper ventilation.
Fugaku has conducted other simulations, recently finding that face masks made out of non-woven fabric are more effective at preventing the spread of COVID-19 than those made of cotton and polyester, the outlet noted.
Researchers at Duke University made similar findings last month, concluding that N95 masks are most effective but three-layer surgical masks and cotton masks are good stand-ins as well