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Duke study: Wearing neck gaiter as mask ‘offers very little protection’ for spread of coronavirus

Limited study of droplet dispersement finds single-layer gaiter like a Buff or Pandana performs poorer than other mask options. Authors caution that more studies are needed.

As mask-wearing to prevent the spread of coronavirus has become commonplace, many cyclists have taken to using something they already had — a stretchy polyester neck gaiter. But a recent study by Duke University indicated that pulling a thin gaiter over the nose and mouth does not limit the projection of droplets that could contain coronavirus as effectively as other options.

“We compared a variety of commonly available mask types and observed that some mask types approach the performance of standard surgical masks, while some mask alternatives, such as neck fleece or bandanas, offer very little protection,” read the study’s abstract.

After this study made international news, with many people focusing on the gaiter portion of the findings, the study’s authors held a briefing for reporters on Thursday, where they acknowledged that the study was intended to serve as “proof-of-principle” of a way that many labs could test the relative effectiveness of masks rather than provide definitive findings on how effective various masks are.

Further, the authors said more testing was needed on gaiters, and that they were not the ones to do it.

Dr. Martin Fischer, Ph.D. developed a technique to visualize the effect of face masks on droplet emissions with laser light and a camera. Photo: Duke University

Dr. Eric Westman, a Duke professor of medicine, said there were two major findings from their study. “People do expel particles when they speak. You don’t have to cough to spread Covid-19,” he said. “The second finding is that some masks work really well, and other masks don’t work as well.”

The Duke study included 14 masks, from hospital-grade N95 to common cotton masks to the one neck gaiter, which the study initially referenced as a ‘neck fleece’. Dr. Martin Fischer, a Duke chemist, clarified that the neck gaiter was a standard polyester/spandex gaiter, not actually a fleece material.

The test used a laser field and a camera to measure the number of droplets projected by a speaker wearing various types of masks.

“We used a laser beam expanded into a light sheet,” said Dr. Martin Fischer, explaining the composition of their test box that a test subject spoke into, projecting droplets as they spoke. “When droplets go through the light sheet, it scatters the light into the camera. By counting the droplets, you can get an idea of how many droplets you emit when you speak.”

Droplets were captured by a camera and counted. A single neck gaiter was found to generate more, smaller particles than other masks. Photo: Duke University

The Duke study found that the “majority of masks worked just fine,” Fischer said. “Everything from N95, which emitted no droplets, to cotton masks, which caught about 80 percent of droplets, which of course is perfectly fine for everyday use.”

The neck gaiter, however, was found to disperse larger particles into a greater number of smaller particles. Fischer said they found that concerning because smaller droplets might linger in the air longer than larger particles.

However, the Duke study authors noted that their proof-of-principle study was done indoors, and did not take into account air movement outdoors. Furthermore, the study’s authors were quick to point out that they only studied one gaiter — “because we just had this mask lying around” — and that they did not test it doubled up, only as a single layer.

Asked if people should be concerned about wearing a gaiter when exercising, Fischer said “absolutely not.”

“There are plenty of other gaiters out there. There are some that have thicker materials. If you double them up, or wear two, we haven’t tested that, but it’s likely that that would be better,” he said.

Duke tested a number of masks, including a single neck gaiter and a bandana. Photo: Duke University

For its part, the company Buff released a statement that its original product was not designed as a mask but as a thermal-regulating layer. However, the company has developed a Filter Mask and Replacement Filter kits specifically for health concerns.

Fischer and Westman said that they do not intend to do more testing.

“I’m inundated with emails. I don’t have the resources to do more mask testing,” Fischer said. “We developed a simple technique, and we hope other people would go out there and replicate this. We did not do a systematic study, but other people can. That is why we published this.”

Westman challenged others to take up the testing of gaiters.

“The burden of proof is on people who say that you can use [a gaiter] and it will protect you, to show that it really does protect,” Westman said. “You realize that we have very little evidence that even cotton masks or bandanas [can protect] – there is very little testing on that at all. Which is really why this investigation I think has gotten so much interest, is because it is just starting the research on this with people wearing these different sorts of things.”

The website ScienceNews was quick to counter that the Duke study should not be blown out of proportion, with an article, “4 reasons you shouldn’t trash your neck gaiter based on the new mask study.”

Westman said that while their study was not conclusive on all the factors of wearing a gaiter outside to prevent the spread of the coronavirus, it should at least give people pause.

“It should tell people to at least take a pause and consider what you are doing,” he said. “If you can blow out a candle through it, this is not going to be protecting people very well, we think.”