As states continue to reopen schools. restaurants and more, a group of researchers looked at which masks are most effective in helping to stop the spread of the coronavirus.
The study, conducted by researchers at Duke University, found that not all masks are created equal. In order to determine which face covers best contain transmission of droplets, the team used a model that included a laser beam and a cellphone.
The researchers used a black box with a hole where a speaker can talk into and placed a cellphone camera to record it.
“The laser beam is expanded vertically to form a thin sheet of light, which we shine through slits on the left and right of the box,” researcher Martin Fischer told CNN.
An algorithm then determines the amount of times the light was scattered by respiratory droplets cutting through the laser beam.
The researchers found, perhaps not surprisingly, that fitted N95 masks are the most effective. However, since the N95 masks are mostly reserved for health care and front-line workers, the researchers also note that three-layer surgical masks and cotton masks that can be made at home or purchased online are also effective in containing the spread of droplets.
“This is a very powerful visual tool to raise awareness that a very simple masks (sic), like these homemade cotton masks, do really well to stop the majority of these respiratory droplets,” Fischer told CNN. “Companies and manufacturers can set this up and test their mask designs before producing them, which would also be very useful.”
However, there are also some masks to avoid wearing. The Duke team found that gaiter masks, or neck fleeces, were the least effective.
“We were extremely surprised to find that the number of particles measured with the fleece actually exceeded the number of particles measured without wearing any mask,” Fischer told CNN. “We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work.”
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