The world’s fastest supercomputer of Japan — Fugaku — found that plastic face visors are almost 100 per cent ineffective at trapping respiratory aerosols.

Fugaku used a simulation to find out that droplets that are less than 5 micrometers in size could easily escape through face visors. The visors are extensively used by corporate staff, and airline staff, among others.

Researchers also said that half of the droplets of 50 micrometers in size could escape the valve.

Researchers warned people against using face visors as an alternative to face masks.

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Tsubokura told the Guardian: “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 further added that small droplets easily escape through the small gap between the face and the visor.

Tsubokura recommended visors only for those who face difficulty in breathing after wearing a face mask. Small children can also sport a visor but only in properly-ventilated outdoors or in indoor settings.

Fugaku also discovered that non-woven fabric face masks are more effective at trapping the droplets and containing the transmission of the virus than those made of cotton and polyester.

Another study corroborates that face visors are infective in controlling the spread of the pandemic. The study was carried out by scientists at Florida Atlantic University where researchers showed, through their model, that aerosol droplets spread around visors and pass through mask valves.

They added that such coverings are not as reliable as masks made of cloth and medical masks, Sky News reported.