Study: Neck gaiters may INCREASE transmission of COVID-19 versus no mask at all
A Science Enthusiast Staff
With well over 5 million cases and nearly 170,000 deaths from COVID-19 in the United States, it's important to state the obvious right off the bat. As we've discussed before until we're blue in the face, masks work to slow the spread of COVID-19. Period. There is no debate here.
Got it? Good.
But just how well they work is something of an open question. And what about all the different types of makeshift masks people are making at home? A new study published in Science Advances helps shed some light on this.
Researchers at the Duke University School of Medicine used a laser and a cell phone camera to measure the amount of droplets that passed through fourteen different types of masks. N95 masks were the most effective, having under 0.1% droplet transmission. The least effective face covering was a neck gaiter (a neck fleece).
In their experiment, researchers found that neck gaiters actually increase droplet transmission, averaging about 110% the transmission of the control (no facial covering at all). This means that according to their results, wearing a neck gaiter increases transmission of COVID-19 10% more than not wearing any type of facial covering at all.
Bandanas were the second least effective type of facial covering, but unlike neck gaiters, bandanas still offered slightly more protection than wearing no covering at all. Knitted masks were also fairly ineffective, too.
The researchers explained why neck gaiters might be worse than wearing no facial covering at all:
We noticed that speaking through some masks (particularly the neck fleece) seemed to disperse the largest droplets into a multitude of smaller droplets (see Supplementary Fig. S5), which explains the apparent increase in droplet count relative to no mask in that case. Considering that smaller particles are airborne longer than large droplets (larger droplets sink faster), the use of such a mask might be counterproductive.
They also noted that, consistent with current CDC guidance, the valves on N95 masks protect the wearer from particles, however may offer decreased protection for others around the N95 wearer due to the valves not filtering expelled air:
Furthermore, the performance of the valved N95 mask is likely affected by the exhalation valve, which opens for strong outwards airflow. While the valve does not compromise the protection of the wearer, it can decrease protection of persons surrounding the wearer. In comparison, the performance of the fitted, non-valved N95 mask was far superior.
The researchers found that homemade cotton masks, as well as polypropylene masks, indeed were fairly effective in limiting the spread of droplets.
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For her article in Yahoo news, Abby Haglage spoke with Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, who stressed the importance of not just wearing face coverings, but wearing ones that are effective:
“People really don’t understand that not all face coverings are equal, and that there are some that are going to be more or less effective,” says Adalja. “And I think that when you’re making these decisions, it’s important to have data behind them.”
Given the rate of droplet transmission from neck fleeces and bandannas, he suggests that Americans move away from both coverings immediately. “I do think they should be abandoned, especially given that gaiters were shown to increase transmission,” says Adalja. “Not every mask is going to be equivalent. ... I think that many people are just wearing these face coverings to check a box and not realizing that in order to serve a purpose they need to be effective.”