Bandannas, gaiters and knit masks are some of the least effective face masks to prevent the spread of coronavirus, according to a new study.
Researchers at Duke University made the discovery while testing 14 different types of masks, according to the study published Friday.
N95 masks, often used by healthcare professionals, work best to stop the transmission of respiratory drops during regular speech.
Other good performers in stopping leakage were three-layer surgical masks and cotton masks, which can be made at home, the researchers found with Duke’s physics department.
But while bandannas and knitted face masks can be a unique look, they did not offer much protection, according to the study.
The scientists also discovered that neck braces, like neck braces, often worn by rounds, were the least effective and in fact allowed more respiratory drops to escape than not wearing a mask at all.
This is because they have been shown to break off larger droplets into smaller particles so that they can slide out the edges of the cover more easily.
“We were very surprised to find that the number of particles measured with the fleece actually exceeded the number of parts measured without wearing a mask,” Martin Fischer, one of the authors of the study, told CNN.
“We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work.”
To test the masks, the scientists used a black box with a laser and a camera for mobile phones.
Someone wearing a face mask would speak in the direction of the laser beam inside the box. Then the amount of respiratory droplets scattered through the tree was picked up by the camera in the back of the box.
A computer algorithm then counted the drops seen in the video to determine how much was leaking through.
The researchers said this was a cheap, effective method to test which face masks worked and which did not.
“This is a very powerful visual tool to make people aware that very simple masks, like these homemade cotton masks, do really well to stop the majority of these respiratory drops,” Fischer told CNN.
“Companies and manufacturers can set this up and test their mask designs before they produce, which would also be very useful.”
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