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PHOTOSurgical and cloth masks are more effective than visors and exhalation valve masks in preventing the spread of Covid-19 infection: this is indicated by the experiment published in the journal Physics of Fluids of the Florida Atlantic University group led by Siddhartha Verma.
The idea of comparing protective devices was born considering that more and more people choose to wear plastic visors and valve masks. The researchers found the answer in an experiment in which they used laser light and a mixture of distilled water and glycerin to generate a synthetic mist similar to that emitted by coughing and sneezing; then they visualized in the dark the droplets emitted by a mannequin with a visor and an FFp2 mask with a valve.
It emerged with such clarity that the visor is able to initially block the forward movement of the drops, which nevertheless exit and move around the visor with ease, spreading laterally and upwards depending on environmental conditions.
In the case of the valve mask, the experiment indicated that many unfiltered droplets are leaking from the valve, making it an ineffective tool to stop the spread of Covid-19, if the person is positive for the coronavirus. . “We focus on the smallest droplets, which can remain suspended in the air for a long time and contain enough virus particles to infect,” Verma noted.
The propagation of droplets with the visor, in the experiment performed by Florida Atlantic University (source: Florida Atlantic University, College of Engineering and Computer Science)
To minimize the risk of SarsCov2 infection, according to the researchers, it would be better to use high-quality cloth or surgical masks without patterns, rather than visors and masks with an exhalation valve. “Even the best of masks have some degree of leakage – concludes Verma – That is why it is important to maintain physical distance even when wearing the mask, to reduce the risk of transmission”.
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