Coronavirus, the confirmation of Science: the masks reduce the aerial transmission of the virus

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Properly worn masks provide an essential physical barrier by reducing the number of viral particles in the breath of asymptomatic individuals who have been infected with the new coronavirus. what they underline in an article in ScienceKimberly Prather and colleagues from the University of California San Diego. Now known: Sars-CoV-2, the new coronavirus, it can be spread by asymptomatic people. A reality that underlines the importance of regularly and widely testing the population, wearing masks and practicing physical distancing. Much of the spread of coronavirus appears to occur through the airborne transmission of aerosols produced by asymptomatic individuals while breathing and speaking. The aerosols can accumulate, remain with their infectious charge in the air in closed spaces for hours and be easily iborn deep in the lungs the authors write. For society to restart – scientists suggest – measures must be implemented to reduce the transmission of aerosols, including wearing all the mask, and carpet testing to identify and isolate infected asymptomatic individuals. Another recent study concluded that the masks reduce the infection by more than 50%.

The delays of the WHO

Many countries have not yet recognized air transmission as a possible route to Sars-CoV-2. Moreover the recommendations of the World Health Organization social distancing and hand washing to reduce viral spread are based on studi on respiratory droplets conducted in the thirties when there was no technology for detecting diffuse particles via aerosol. More recently, measurements show that intense coughing and sneezing that spread the largest saliva droplets can create thousands of aerosol particles that can travel even further. Recent work has estimated that a single minute of talking aloud can generate between 1,000 and 100,000 aerosol particles containing virions or virus particles suspended in the air. Another work just published in Lancet confirms that the transmission of Sars-CoV2 also occurs from small droplets of aerosol in poorly ventilated spaces for this ventilation, and not only the masks, considered crucial. After a long phase of denial by the WHO and the competent authorities, these scientific works finally confirm on the one hand the aerial transmission of the SARS-CoV-2 virus in closed environments, on the other hand also the way to reduce the consequent contagion. In fact, the priority implementation of engineering choices such as adequate ventilation accompanied by the correct use of personal protective equipment makes it possible to reduce the risk even in closed rooms. Giorgio Buonanno professor of technical physics at the University of Cassino and at the Queensland University of Technology in Brisbane, Australia.

How the droplets move

The authors of the work on Science write that little is known about how infectious respiratory droplets move in the air but carry theexample of cigarette smoking: the distance from which I can smell a smoker’s cigarette indicates the distance from which I can inhale infectious aerosols. And in a closed room with asymptomatic individuals, infectious aerosol concentrations can increase over time. The probability of contracting the infection indoors will depend on the total amount of inhaled Sars-CoV 2. The minimum dose of Sars-CoV-2 that leads to the infection is not known, according to the authors, but the transmission into the air through aerosols has been documented for other respiratory viruses including measles, SARS and chicken pox.

The use of masks

The countries that have been most effective in limiting the spread of Covid-19 have universal use of the masks implemented, the experts note in conclusion. particularly important, therefore – they underline – to wear these devices in places where high concentrations of viruses can accumulate, such as healthcare facilities, airplanes, restaurants and other crowded places with reduced ventilation.

May 28, 2020 (change May 28, 2020 | 18:11)

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