It has been discovered that plastic face shields are not as effective in preventing the spread of the coronavirus as initially thought.
A simulation using the world`s fastest supercomputer known as Fugaku has shown that plastic face shields are almost completely ineffective at trapping respiratory aerosols. Thousands of people working in service industries have been making use of plastic visors as face coverings.
However, according to the simulation modelling in Japan, nearly 100% of airborne droplets of less than 5 micrometres in size escaped through the plastic visors of the kind often used by service industry workers.
A government-backed research institute in the western city of Kobe, Riken, added that almost half of the larger droplets measuring 50 micrometres (1 micrometre is 1 million of a metre) escape into the air.
The team leader at the Riken`s centre for computational science, Makoto Tsubokura, said: “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.
“This is especially true for small droplets of less than 20 micrometres,” he said, adding that all the smaller aerosol particles find their way into the air through the gap between the face and the face shield. “At the same time, it somehow works for the droplets larger than 50 micrometres.”
Senior scientists in Britain have blasted the government for putting more emphasis on hand-washing and inadequately stressing on aerosol transmission and ventilation. Japanese health authorities have been stressing on these factors since the beginning of the pandemic, after using simulation.
In light of the modelling, world governments should put sufficient emphasis that people should not rely on plastic face shields as their ineffectiveness has been proven.