A new study from Duke University, measuring the efficacy of various masks and face coverings, suggests that some neck gaiters may be ineffective in slowing the spread of COVID-19.
However, the neck gaiter tested, which was made out of a lightweight 'polyester spandex material,' ranked worse than the no-mask control group, according to the study.
Martin Fischer, Ph.D., an associate research professor in the departments of chemistry and physics at Duke University, told TODAY Health that the study does not say that "all neck gaiters are bad" but only "measured data of one gaiter with one speaker" and "does not represent all neck gaiters."
The study analyzed 14 masks and coverings by using a tool that allowed researchers to track individual particles released from a person's mouth when they spoke the phrase "Stay healthy, people." Speakers said the same phrase while wearing the different models of masks, and no masks at all, to compare. Each face covering was tested 10 times.
In a video of the study, created and shared by researchers, Fischer, warned that the neck gaiter used might actually be "counterproductive": There were more particles in the air after speaking through the gaiter than after wearing no mask at all. Fischer said that the porous fabric seems to break bigger particles into smaller particles, which are more likely to linger in the air.
"It’s not the case that any mask is better than nothing," he said. "There are some masks that actually hurt rather than do good."
Dr. Scott Segal, a professor at the Wake Forest School of Medicine, agreed with Fischer's assessment of the gaiters, calling the conclusion "a reasonable speculation" and adding that a study he conducted himself showed similar concerning results.
"We are all sort of in agreement that gaiters are probably not your best choice," Segal told TODAY. "They’re super convenient, they’re easy to put up and down, but they’re probably not the best face covering."
Neck gaiters weren't the only mask whose efficacy was called into question: The study showed that masks made from bandanas, knitted masks and N95 masks with ventilation valves were also less effective than others.
"Bandanas don’t work," Segal said. "Even a doubled-up bandana is a poor filter. It's a very open weave and thin material, and are considerably less effective even against large particles. They don’t seem to perform terribly well."
Segal said that for most cloth or fabric masks, people should try to use a material known as 'quilting cotton,' or cotton with a flannel inner layer, since it's thicker and particles will not pass through as easily.
"As best we can tell, the difference between different cloth masks or face coverings really comes down to the tightness of the weave of the fabric," Segal said. "We believe that the better performing masks have a tighter weave. That's not just thread count — it also depends on the thickness of the fibers themselves. Higher quality cottons made from thicker yarns leave less gaps between the fibers on the cloth."
Fischer emphasized to TODAY Health that he doesn't want to discourage mask use.
"Our demonstrations simply show that there is a wide range of mask performance, and hope that everyone realizes that there is a trade-off between comfort and protection," Fischer said. "A mask that lets through air with very little resistance might not filter emitted particles very well."
CORRECTION (August 25, 2020, 12:43 p.m.): The headline on this article misstated the study's finding on bandanas. They were not shown to be worse than wearing no mask at all so we removed the reference. This story was also updated to clarify that only one specific type of neck gaiter was used in the study. The data does not represent all neck gaiters.