Masks with valves and face shields allow spread of COVID-19: Study

The pandemic has given us a few companions like a face mask, a bottle of hand sanitiser, gloves and a face shield. However, a new study reveals that plastic face shields or masks fitted with a valve can spray invisible droplets over a very wide area when they sneeze or cough, making the devices ineffective at preventing the spread of coronavirus when used on their own. 

According to a report published Tuesday in the US journal Physics of Fluids, researchers from the Florida Atlantic University used vertical and horizontal laser sheets to create a simulation model to track tiny droplets of distilled water and glycerin. 

These droplets spread from a hollow mannequin head fitted with a plastic face shield or a mask with a breathing valve on it.

According to the researchers, the face shield initially blocks the passage of the droplets as they move forwards, but "the expelled droplets can move around the visor with relative ease and spread out over a large area".

As for a mask with a valve fitted to make breathing easier, "a large number of droplets pass through the exhale valve unfiltered, which make it ineffective in stopping the spread the COVID-19 virus if the person wearing the mask is infected."

As per the researchers, high-quality cloth or medical masks of plain design are better in helping prevent the spread of the virus.