Face shields offer no protection against coronavirus if an infected person nearby sneezes without a mask on, a study shows.
Researchers used computer models to visualise the spread of droplets around a face shield ejected by a human sneeze from 3ft (1m) away.
It reveals ‘vortex rings’ produced by the sneeze carry infectious particles to the face shield in less than a second and stick to the edges of the plastic.
Researchers say if the timing of this wave of coronavirus particles coincides with the face shield wearer breathing in, the person can become infected.
Many people have opted for the face shields in preference to masks as they are less restrictive and claustrophobic.
They also allow people to see a person’s mouth, which assists with lip-reading and non-verbal communication and is beneficial for people who are hard of hearing.
Throughout the Covid-19 pandemic they became popular with many groups, including beauticians and hairdressers.
A separate scientific paper published in July also found face shields are not protective against Covid-19 — but masks are.
Swiss officials investigated an outbreak of ‘several’ coronavirus cases that occurred at a hotel in a village in the Alps — even though employers took precautions.
Experts revealed only those who wore plastic visors were infected. But no-one who wore a mask, either alone or in addition to a face shield, caught the coronavirus, according to the study