As masks continue to be a part of everyday life, researchers and scientists from Duke University took a look at all the different types of masks people wear in order to determine which ones are the most effective, and which ones you shouldn’t rely on.
In a new study, researchers used a simple way to evaluate how effective different types of masks are. They analyzed 14 types of masks and found that “some easily accessible cotton cloth masks are about as effective as standard surgical masks,” reports The Washington Post.
However, things like neck gaiters, which are often produced for athletic purposes and made of thin, stretchy material, might actually be worse than wearing no mask at all. Warren S. Warren, one of the study’s co-authors and a professor of physics, chemistry, radiology, and biomedical engineering, said that it’s very easy to tell that masks do work.
“You can really see the mask is doing something,” he said. “There’s a lot of controversy and people say, ‘Well, masks don’t do anything.’ Well, the answer is some don’t, but most do.”
Martin Fischer, a chemist and physicist, used a contraption that “harnesses the power of a laser,” as well as a cell phone camera, to create “a device that allowed his team to track individual particles released from a person’s mouth when they are speaking.”
They had people say the same phrase into a box without a mask on, and then they repeated the process while wearing one. Each of the 14 types of face coverings was tested 10 times. When particles and droplets leave the speaker’s mouth, they pass through a sheet of light created by the laser hitting a lens, and the camera could take a photo of those moments.
“We were able to use the scattering, and then tracking individual particles from frame to frame in the movie, to actually count the number of particles that got emitted,” Warren said.
Of all the masks they tested, a correctly fitted N95 mask was the most effective. On the opposite end of the spectrum, neck gaiters, which are usually made to be breathable for use by runners and other athletes, actually ranked worse than the no-mask control group.
Warren said, “These neck gaiters are extremely common in a lot of places because they’re very convenient to wear. But the exact reason why they’re so convenient, which is that they don’t restrict air, is the reason why they’re not doing much of a job helping people.”
Neck gaiters could be less than effective because the material they use is often too porous. The high droplet count could be caused by larger droplets being broken up by the fabric into lots of little particles that are more likely to hang out in the air for a longer amount of time.
The study found that surgical masks work well, as do some layered cotton face masks, which have become extremely common. Some of the least effective masks were knitted masks and bandanas. But “fleece” neck gaiters fared the worst.
You can perform your own simple test at home to see, generally, if your mask will be helpful. “If you can see through it when you put it up to a light and you can blow through it easily, it probably is not protecting anybody,” Warren said. While he acknowledges that the scope of the study was small, the general takeaway is that masks do work. And we should all be wearing them to protect ourselves and others while out in public.