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]]>People who’ve tried to exercise outside wearing a mask other than a neck gaiter have come to the unsurprising conclusion that they find it harder to breathe. The neck gaiter, made of very thin, stretchable material, addresses that problem, allowing exercisers to get as much air as they need. Unfortunately, investigators with Duke University also found that neck gaiters provide no protection against coronavirus disease 2019 (COVID-19) and that wearing them may be worse than wearing no face covering at all when it comes to stopping the spread of the virus. The findings were published in a study in Science Advances.
Neck gaiters weren’t the only face coverings tested: in all 14 were analyzed, from N95s (unsurprisingly judged to be the most effective in containing COVID-19 spread) to bandanas (not much more effective then neck gaiters, according to the study).
As a news release from the university explains, the disconcerting discovery about neck gaiters came about as a result of a Duke professor wanting to find out what are the most effective face coverings. That professor needed the information in his effort to provide masks and other face coverings to an underserved population in Durham, N.C.
Enter Martin Fischer, a chemist and physicist at the university. He constructed a simple testing device using a laser (you can find them online for about $200), a cell phone camera, a cardboard box, and a lens. Fisher was able to track particles emitted by individuals.
The investigators noted that “In brief, an operator wears a face mask and speaks into the direction of an expanded laser beam inside a dark enclosure. Droplets that propagate through the laser beam scatter light, which is recorded with a cell phone camera. A simple computer algorithm is used to count the droplets in the video.”
After testing the 14 masks that were considered commonly available, they found some fascinating tests. First and—again—not surprisingly, N95 respirators and surgical masks provided the most protection/containment of droplets.
Cotton masks performed quite well, which is reassuring as they are frequently used in the community. Two important findings were also reported: “We noticed that speaking through some masks (particularly the neck fleece) seemed to disperse the largest droplets into a multitude of smaller droplets … 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. Furthermore, the performance of the valved N95 mask is likely affected by the exhalation valve, which opens for strong outwards airflow.” The emphasis on valved N95s is a good reminder about the role of exhaust valves and how they not only provide poor source control, but also cannot be used in sterile environments.
The findings of this study are not only informative in terms of the potential amplification done by neck fleece masks but reiterates the importance of infection preventionists making informed decisions for the community in terms of masks. Ideally, surgical masks would be helpful as they offer protection for not only those around the wearer, but also for the person wearing them.
As hospitals consider more sustainable approaches to ensure masking compliance in visitors but also want to support employees beyond the walls of the healthcare facility, cloth masks might pose a viable option. Moreover, providing the public with better guidance on masks that offer more protection while not impacting healthcare supply chains, is beneficial to all. More insight into the efficacy of widely available masks is immensely important.
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]]>Using thin, stretchy neck gaiters as a face covering might be ineffective at stopping the spread of the coronavirus, and could even spread the virus further than not wearing a covering at all, according to a new study. Researchers from Duke University found that the neck gaiter they tested was “worse than nothing.”
“The neck gaiter that we tested did essentially nothing, and worse than nothing, because it appeared to make large droplets into small droplets,” Isaac Henrion, the study’s co-author, told CBS News. Henrion is also the coordinator of Cover Durham, a community project to distribute tens of thousands of masks to vulnerable people.
The experiment involved only a small number of speakers and face coverings, and the researchers stressed that more testing is needed — some gaiters might work better than others, depending on how they’re made.
The neck gaiter is a circular piece of fabric that sits around a person’s neck and can be pulled up to cover their mouth and nose. The issue with the convenient cover-up is likely not with its design, but with the fabric it is typically made from.
According to Henrion, the study tested a neck gaiter made of a thin, stretchy polyester, which is a commonly sold style. Instead of stopping droplets that can contain the virus from escaping into the air, the fabric appeared to turn large droplets into smaller ones known as aerosols.
Niklas Halle’n / Getty
Aerosols are microscopic droplets that are produced when people cough, sneeze or talk, but they do not fall to the ground in the same way larger, visible droplets do. Henrion described an aerosol’s path like that of a paper airplane flying through the air and getting caught on currents that are invisible to the naked eye.
“They’re really tiny, they’re really invisible, they’re buoyant, they don’t fall to the ground, gravity doesn’t act on them,” Kimberly Prather, distinguished chair in atmospheric chemistry at UC San Diego and an expert on aerosols, told CBS News chief medical correspondent Dr. Jonathan LaPook in June.
“And so when (aerosols are) released by someone who’s infected, doesn’t know it, and is talking in a room, they can just build up in a room over time and whoever’s in that room can inhale those and become infected,” according to Prather.
The danger of creating aerosol droplets is that it’s harder to protect ourselves from aerosols than from larger droplets.
“If you inhale tiny aerosols, those go deep into your lungs and can bypass your immune system … that’s why you don’t have symptoms [at first],” Prather explained. “The virus just takes off and your body is under attack, and you don’t know it for five days until it grows up in your upper respiratory tract, then it triggers your immune system, and then you have symptoms.”
“Aerosols are increasingly considered to be a major source of transmission, especially in unventilated and crowded spaces where a strong concentration can build up over time,” according to Henrion. The extent to which aerosols may carry the coronavirus is still being researched, but evidence suggests they play a role.
Study: Multi-layer face masks work better
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Duke’s study focused on droplet production while talking, as opposed to coughing or sneezing, because research has shown that more than half the people infected with COVID-19 do not have symptoms, and therefore are generally not coughing or sneezing, according to Henrion.
“Talking really is the way that asymptomatic transmission happens,” he said.
Dr. Neeta Ogden told CBSN on Wednesday that numerous coronavirus outbreaks, including those among passengers on the Diamond Princess cruise ship, in Boston’s homeless population and the workers at a Tyson poultry factory, happened when “there was a high level of infection and a great percentage of people who were asymptomatic.”
Global coronavirus infections have doubled in just six weeks and climbed past 20 million, according to data from Johns Hopkins University. More than half of those positive cases come from just three countries: the United States, Brazil and India. Since the first cases were detected in the U.S. in January, more than 5 million Americans have been diagnosed and more than 165,000 have died.
Henrion noted that countries where a large percentage of the population wears masks were able to stop community transmission.
“The evidence now from many fields is overwhelmingly that masks work,” he said.
While the study did not set out to create a definitive ranking of masks, Henrion said that N95 and standard surgical masks released the least amount of droplets. N95s yielded the best results, and surgical masks came in second, stopping 90-95% of droplets. Simple two-layer cotton masks were effective at stopping 80% of droplets from getting out when participants spoke.
As for neck gaiters, Henrion stressed that the study was preliminary, and did not conclusively determine whether a gaiter’s fabric or construction was responsible for producing smaller droplets. A neck gaiter with two layers of cotton could be more effective.
Without easy access to PPE, many people have turned to making their own masks. The study showed that homemade versions can be effective, but people should be mindful of their mask construction and fit.
“Further research is needed to investigate the performance of bandanas and neck gaiters, since our study is only a proof of concept for the experimental method,” Henrion said.
Martin Fischer, an associate research professor in Duke’s chemistry department who took part in the study, told WRAL-TV it wasn’t meant to rate different face coverings, adding that “Not all … neck gaiters are bad. There are plenty good ones out there. It depends so much on the material, on how many layers you wear.”
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]]>One popular style of face covering may not be doing much to limit spread of the coronavirus, according to a study out of Duke University.
The researchers found that while most of the cotton, cloth or surgical-style masks tested were effective at limiting the amount of respiratory droplets a person expelled while talking, the “neck gaiter” or neck fleece actually resulted in more small droplets being expelled.
“We attribute this to the fleece, the textile, breaking up those big particles into many little particles,” Martin Fischer, an associate research professor at Duke said in a news release.
The novel coronavirus that causes COVID-19 is spread from person-to-person mostly through respiratory droplets that we all expel out of our mouths when we talk, sneeze, cough or breathe heavily, according to most experts.
Fischer said it’s possible that releasing more small droplets through a thin mask is worse than expelling larger droplets with no shield at all.
“[The smaller particles] tend to hang around longer in the air, they can get carried away easier in the air, so this might actually be counter productive to wear such a mask,” Fischer said. “It’s not the case that any mask is better than nothing. There are some masks that actually hurt rather than do good.”
However, some have said that conclusion is premature and we don’t have enough information to declare that those masks do more harm than good. Slate news director Susan Matthews points out that the researchers tested only a single subject with the gaiter-style mask, increasing the chances that the mask simply didn’t fit, or that there was some other issue with either the mask or the test subject.
The subject also only repeated the short phrase “stay healthy, people,” 10 times for each mask. The subject did not speak in different volume levels, cough, sneeze or simulate other conditions like heavy breathing during exercise. Gaiter masks are very popular among runners because of their lightweight construction and looser fit.
A study out of the University of Wisconsin-Madison from July found that gaiters were more effective than other types of masks at catching droplets from a simulated cough, but that study used “snug-fitting” homemade gaiters made of tightly woven fabric with a metal nose-piece and elastic to ensure a good fit.
Matthews also notes that we don’t know whether a person expelling a higher number of small droplets is more likely to spread the disease than a person producing fewer, larger blobs of virus-laden spittle.
The findings of the Duke team were published online last week in Science Advances, a peer-reviewed journal.
Fisher and the team at Duke tested 14 different kinds of masks using cardboard, laser lights and a cell phone camera, as you can see in the short video below.
The subject repeats the same phrase into the contraption, first with no mask, then with the different styles of masks to see which were most effective. The laser makes the droplets coming out of a person’s mouth visible and the camera records those droplets to be counted.
The team found that surgical masks, as well as cotton, cloth and polypropylene masks were effective in blocking the droplets from being spread when the subject spoke in a normal voice. The best-performing masks were the medical-grade N95 masks — without valves — used by medical professionals.
The neck fleece (Mask #11 in the photo above) actually resulted in more droplets being counted. The bandana reduced the number of droplets by about half, the others reduced the droplet count to 20 percent or less of the mask-less count.
One of the researchers told The Washington Post that the gaiter that tested poorly was made of a lightweight, polyester spandex material, marketed as a breathable item for outdoor sports activity.
“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 S. Warren, a co-author of the paper told the Post.
N95 medical masks with valves performed about as well as cotton masks, with the researchers noting the valves were designed to keep droplets from entering the mask from the outside, not to stop the person wearing the mask from expelling droplets that others could then breathe in.
The overall takeaway from the paper is clear, however. While some masks perform better than others, most masks are effective at reducing the droplets that spread the coronavirus.
“Wearing a mask is a simple and easy way to reduce the spread of COVID-19,” Dr. Eric Westman, a Duke physician who worked with Fischer to design the experiment, said in a news release. “About half of infections are from people who don’t show symptoms, and often don’t know they’re infected. They can unknowingly spread the virus when the cough, sneeze and just talk.
“If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else. In the absence of a vaccine or antiviral medicine, it’s the one proven way to protect others as well as yourself.”
This study was designed as a proof-of-concept of the researchers’ technique to measure droplet spread. The researchers say further research is needed to test different masks under a variety of conditions, such as speaking at different volumes, or coughing and sneezing.
“We certainly encourage everyone to wear a mask, but we want to make sure that when you wear a mask and you go to the trouble of making a mask, you make one or wear one that actually helps not just you but helps everyone,” Fischer said.
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There’s a new study claiming that neck gaiters like Buffs are worse than not wearing a mask at all. I’m not convinced that this study should be taken at face value, but it’s also reasonable to be suspicious of Buffs, bandanas, and other face coverings that aren’t designed to do the job of a mask.
(To be totally clear: Buff is a company that makes thin, spandex-y neck gaiters that have become eponymously known to many as “buffs.” They also make a purpose-built face mask. That mask was not tested in the study we’re talking about here.)
For more on face masks, check out the video below:
We’ve long known that N95 respirators do the best job of protecting both the wearer and others. Surgical “procedure” masks—those disposable medical masks—are the next best thing, keeping most (but not all) of your respiratory droplets to yourself while possibly providing protection from others.
Since those masks aren’t always available, cloth masks are what most of us have ended up wearing. Cloth masks provide protection in a similar way to disposable procedure masks, although they may not be as effective.
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That said, not all masks are equal. As we all scrambled to find cloth masks, companies started advertising different types. Anyone who sells gaiters was advertising their gaiters; companies that made masks with valves were selling masks with valves. Of course, that doesn’t mean these are the best choices.
What this study found
So far, there is not a great way to test masks to see if they are “good enough” to protect against the coronavirus. Medical masks go through certain quality-control checks, but fashion masks have no such protocol. Nor do the ones you sew or improvise at home.
So a group of researchers from North Carolina published a paper describing an inexpensive tool that could be used to test masks. The device is basically a box with a laser and a cell phone camera; you stick your masked face up to the box and speak into it. Light from the laser bounces off the droplets that spray out of your mouth (or that don’t, depending on how well the mask works), and it’s recorded by the camera.
The device doesn’t test whether people got sick or whether an infectious dose of virus was delivered; it just looks for droplets in the air. No coronavirus was involved in this test.
So, to test the device, researchers spoke into the box while wearing a variety of masks. As expected, people produced very few droplets when wearing N95s, with surgical masks performing better and cloth masks varying according to their materials and construction.
Here’s the big caveat, though: this was a proof-of-concept to see if the box could measure droplets, and if the droplets looked different from mask to mask. It is not a definitive test of the masks themselves. In fact, the researchers wrote in their conclusion:
Again, we want to note that the mask tests performed here (one speaker for all masks and four speakers for selected masks) should serve only as a demonstration. Inter-subject variations are to be expected, for example due to difference in physiology, mask fit, head position, speech pattern, and such.
What should we know about different types of masks?
First, that if something isn’t really a mask, we shouldn’t expect it to perform like one. Both the CDC and WHO recommend that a mask fit snugly around your mouth and nose, which rules out buffs, as well as bandanas tied bank-robber-style. They also warn against wearing a mask with an exhalation valve, since that just spews your germy air out into the world.
None of this is new. What is new in this study is the suggestion that a buff may be worse than nothing, because its open weave seems to split bigger droplets into smaller ones. That could be a problem. See all those weasel words? That’s the best way I can accurately describe the results. It’s very possible buffs could turn out to be worse than nothing, but the question needs more study. Nobody has studied whether buffs actually increase the chances that someone might get sick.
I think it’s worth reconsidering your buff, if you wear one. I know a lot of runners like to have one around their neck so they can pull it up if they pass someone. We now have some data to suggest that may not be a great idea, but we already knew that a buff is not really a mask—so maybe we shouldn’t have been relying on them in the first place.
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