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In an opinion published in the scientific journal. marmaladeAccording to American scholars, there is talk of the effectiveness of face shields in contrasting the spread of the Covid-19 epidemic. Remembering like me Centers for disease control and prevention. (CDC) The United States has recommended that everyone wear a cloth mask in public to control the spread of the virus, expressing the belief that face shields (clear plexiglass visors or others) may represent a better option.
Visors duration
Beyond the opinion of the researchers, the disclosed data and some considerations are interesting: let’s start with these. Face shields can be produced and distributed quickly and conveniently – they do not require special materials for fabrication, and production lines can be reconverted fairly quickly. Many companies have already done so (also in Italy), so their availability is currently good. In the United States (it is read in the article) it would be “greater than that of surgical masks”. For optimal protection, the visor should extend below the chin up to the ears laterally and there should be no exposed space between the forehead and the beginning of the barrier. Also, while surgical masks, the authors of the text write, have a limited life and little chance of being recycled, face shields can be reused indefinitely and can be easily cleaned with soap and water or common household disinfectants. They are comfortable to wear, protect the airways and prevent the user from touching their faces. People who wear them do not have to take them off to speak: they remind interlocutors of the need for social distancing, but allow them to see facial expressions and lip movements.
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Barrier from 96 to 68 percent
And let’s go to the protection data: in this case there are still no studies against Covid-19, but the effectiveness of the viewers was tested in 2014 to detect the influenza virus (another respiratory virus that spreads through infected droplets) . In the simulation study, facial displays were shown to reduce immediate viral exposure by 96% when used by a healthcare professional within 46 cm of a “large” drop cough simulator. When a cough simulator with smaller particle production (3.4 µm aerosol) was used, the visor was less effective, blocking only 68% of the particles. If the result was tested after 30 minutes (after which the cough and aerosols had dispersed in the room), the face shield reduced aerosol inhalation by just 23%.
Like cloth masks, but on the contrary.
For comparison, self-produced cotton masks (with a dense fabric) have a filtering power of 90% for large particles (drops) and 24% for small particles (aerosols). When made with a cotton shirt, two coats captured 77 percent of the drops and 15 percent of the sprays. Therefore, the effectiveness of facial displays looks good, although the original study is written: They can substantially reduce short-term exposure to large infectious particles, but smaller particles can stay in suspension longer and flow more. easily around the face shield to be inhaled. They could be an alternative (or an addition) to masks in some workplaces. It should be noted, however, that no study has evaluated the effects or potential benefits of riflescopes in the case of direct emission by those who use them from infected droplets.
May 5, 2020 (change May 5, 2020 | 10:04)
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