Face shields give no protection from coronavirus: Study
Published: 06:03 PM, 23 September 2020 Updated: 06:05 PM, 23 September 2020
A study has found wearing a plastic face shield gives no protection from coronavirus; Photo: NurPhoto/PA Images
The plastic face shields, which was believed to prevent Covid-19, do not work as nearly 100 percent of tiny airborne droplets released by the coronavirus-infected patients enter through the visors, a recent study conducted by the Riken Centre in Japan has warned.
So far, the industry experts believed that the face masks provided adequate protection from the virus, as a result, the British government has recommended them for hairdressers, barbers, nail technicians and tattooists as a barrier between them and the customer, according to Daily Mail.
But the effectiveness of face shields raised questions after a study revealed almost 100 percent of airborne droplets, smaller than five micrometers in size, released when talking and breathing, allowing them to enter through the visor.
The World Health Organization (WHO) says face shields can help prevent the virus called SARS-CoV-2, however, the agency says they only work in “combination” with other safety measures such as wearing a mask, social distancing, and frequent hand-washing.
Face shields do not completely cover the entirety of the face, leaving room for droplets expelled by the mouth and nose to escape.
“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,” Makoto Tsubokura, team leader of the study carried out by the Riken Centre, told The Guardian.
He said, “This is especially true for small droplets of less than 20 micrometers, at the same time, it also works for the droplets larger than 50 micrometers.”
Those advised not to wear face masks, such as those with underlying respiratory issues or small children, could wear face shields instead, but only in outdoor or indoor settings that are properly ventilated, he added.
The ineffectiveness in halting the spread of coronavirus was also found from the research conducted by the Florida Atlantic University’s College of Engineering and Computer Science on September 1.
In the study, published in the journal ‘Physics of Fluids’, scientists placed fluorescent substances in droplets so that they could monitor their spread. A mannequin was also set up to expel sneeze and cough droplets, with a mixture of distilled water and glycerin to generate a synthetic fog. Face shields were revealed other particles entered through visors.
The British Government’s Scientific Advisory Group for Emergencies (SAGE) has also recommended that hairdressers should wear face masks rather than face shields as there is ‘no evidence’ protection against Covid-19.
Airborne transmission is different from droplet transmission. They can remain in the air for long periods of time, meaning transmission can occur when the contagious person has left the room, and be transmitted to others over distances greater than one meter.