A new American study has proven that visors and valve masks are not effective in the fight against Covid-19.
People wearing plastic visors or masks with valves can still cover a wide area with droplets after a sneeze or a cough, as depicted in the laser visualisation experiment carried out by researchers at Florida Atlantic University. The study showed that such products are ineffective in stopping the spread of coronavirus.
In the study, published on Tuesday by American review journal Physics of Fluids, researchers used a mannequin to simulate sneezing and coughing, observing the manner in which fluids spread by filming how droplets passed through horizontal and vertical green laser beams positioned near the mannequin.
Although visors block the initial forward motion of the action, the expelled droplets can pass around the visor with relative ease and spread out over a large area depending on light ambient disturbances.
When testing valve masks, the research team stated that a large number of droplets pass through the exhale valve unfiltered. This type of mask is designed only to filter the air which is inhaled, rather than exhaled.
In conclusion, the study deems both items to be ineffective albeit comfortable, and recommends the wearing of a surgical or fabric mask as per the sanitary recommendations made by the USA and other countries.