A study has found plastic face shields don’t protect against Covid-19 if aninfected person wearing no mask sneezes nearby.

Researchers revealed “vortex rings” produced by the sneeze carry infectiousparticles to the face shield in less than a second and stick to the edgesof the plastic. If the timing of this wave of coronavirus particlescoincides with the face shield wearer breathing in, the person can becomeinfected, they said.

A Japanese computer simulation revealed almost all airborne dropletssmaller than five micrometres in size released when talking and breathingescaped through the visor and half of larger droplets measuring 50micrometres in size, given off by coughs and sneezes, found their way intothe air, posing a risk to others.link

The latest study by researchers at Fukuoka University in Japan andpublished in the journal Physics of Fluids further is yet another proofagainst the use of face shields.

A shocking video published alongside the study illustrates how air flowfrom a sneeze can make its way around and up the inside of a face shieldand into a person’s mouth or nose, rendering the PPE useless without a facemask being worn as well.

Researchers looked specifically at sneezes because of the creation of aphenomena known as vortex rings.

“A vortex ring is a donut-shaped vortex that is generated by aninstantaneous ejection of fluid from a circular orifice,” said study authorDr Fujio Akagi. “This resembles bubble rings made by dolphins.”

“The vortex rings generated by the sneeze capture the microscopic dropletswithin the sneeze and transport them to the top and bottom edges of theface shield.”

“We are currently developing and demonstrating several improved shields,”said Dr Akagi.