Plastic face shields, which are mainly used by healthcare workers, have proven to be ineffective, according to a simulation by Japan's fastest supercomputer Fugaku.

One-hundred percent of airborne respiratory droplets smaller than five micrometers can pass through plastic visors according to a governmental research institute, Japan’s Riken.

The smallest aerosol droplets are becoming airborne and some larger droplets, measuring up to 50 micrometers, are escaping into the air behind the mask, according to the Guardian.

A member of Riken’s computational science team, Makoto Tsubokura, said the simulation combined air flow with tens of thousands of different-sized droplets amd proved that these faceguards are useless in fighting COVID-19.

Tsubokura suggests allowing individuals with respiratory problems and younger children to wear face shields in open spaces and well-ventilated areas.

Fugaku recently found that non-woven face masks are more effective in terms of blocking airborne droplets than cotton or polyester facemasks.