Months after the COVID-19 pandemic started there's still some debate over which face-covering works the best. Kalispell Regional Medical Center Chief Medical Officer Dr. Doug Nelson told MTN News that a recent study at Duke University showed the effectiveness of different types of face coverings.
"There was a study out of Duke earlier this summer that basically measured how many respiratory droplets came through a whole variety of different face coverings," said Nelson. "And the best for preventing respiratory droplets coming through were the N-95 masks."
Dr. Nelson said that N-95 masks work the best, while others -- such as "neck buffs" -- may be as bad as not wearing anything. "The worst were the polypropylene neck gaiters or buffs," said Nelson. "In this particular study, they had more respiratory (droplets) come through than if people weren't wearing anything at all."
Dr. Nelson says that study didn't examine different kinds of neck buff fabrics and their effectiveness, but only tested a single layer polyester neck buff. He explained that the important thing is to wear a mask with multiple layers.
"Have fibers going in different directions. A droplet may be absorbed into the first layer but then may not pass through the second and third layers," Dr. Nelson said. He added that if you can't get an N-95 mask, a paper surgical mask or a multi-layered cotton mask is the next best thing.
Here is the video produced by Duke University, with this summary: "Dr. Martin Fischer, Ph.D., from Duke University, developed a simple, low-cost technique to visualize the effectiveness of different face coverings on droplet emissions during normal wear. Testing several face coverings, the researchers found that the particles can be blocked by some, but not all recommended face coverings. N95s without valves, and surgical, and polypropylene masks worked best. Cotton face coverings provided some coverage. Bandanas and neck fleece didn’t block the droplets very much."
The Washington Post, however, recently reported that in response to the Duke study, some aerosol scientists conducted their own experiments, which showed that when a single-layer gaiter is worn doubled-up, it is "highly effective at blocking a range of particle sizes," according to the results of tests done by Linsey Marr, a civil and environmental engineering professor at Virginia Tech who studies aerosols. “Gaiters are as effective as a mask made out of a similar material,” Marr said. “If you double-over a neck gaiter, you can get very good protection.”