Researchers from Duke University, in the United States, conducted a study to verify the level of effectiveness of the different types of chinstraps. Public health experts determined that masks are a fundamental tool to reduce the spread of covid-19, but that not all are equally effective and some may even be counterproductive.
According to the study published in the American journal Science Advances
, chinstraps N95 without valve -reserved in the United States for hospital staff- they are the most effective, while makeshift homemade face masks with fleece collars provide no protection and increase the spread of the virus.
The study measures the amount of saliva droplets filtered by different types of masks. N95s reduce droplet transmission by 99.9 percent protection, closely followed by surgical chinstraps (99.5). Pleated cotton and propylene chinstraps have 85-95 percent protection.
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The study states that the worst masks are bandanas and fleece collars. This cloth, the researchers note, increased the number of droplets ejected, possibly because the material helped disperse the larger droplets into many smaller ones. The bandanas have an average protection of 50 percent, while the fleece collar does not filter any drops from the speakers.
“The notion that ‘anything is better than nothing’ proved not to be true”said Eric Westman, one of the study’s co-authors. The US government discouraged the private purchase of medical masks – due to the shortage – and recommended to the population the purchase of cloth masks.
“We need to increase the production and distribution of surgical masks,” tweeted Tom Frieden, former director of the Centers for Disease Control and Prevention (CDC) during the administration of President Barack Obama, after the study was published. Between 30% and 40% of infected people may show no symptoms, but they still transmit the virus unknowingly by coughing, sneezing, or just talking.
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Researchers at Duke University designed the study to determine how many drops of saliva pass through the chinstrap when the wearer coughs, sneezes or talks. For that, they asked different people to come into a room and say “Stay healthy, people” and “Take care” in the direction of a laser beam wearing a mask. The laser allowed to see the quantity of drops expelled.
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