By David Lao Global News
Posted December 18, 2021
Canadians are being urged to ditch certain types of masks in favour of ones experts say will provide more protection against the new, rapidly spreading Omicron variant.
The head of Ontario’s Science Advisory Table, Dr. Peter Juni, said Friday that single-layer cloth face masks may not be enough to protect against Omicron.
“The issue here is if you have a single-layer, the ability to filtrate is absolutely minimal and doesn’t make a difference whatsoever,” said Juni, who pointed to the use of KN95 respirators as a more effective option.
The renewed discussion about mask use comes as Canada’s Omicron-driven fifth wave continues to drive daily case counts to record numbers not seen in months, pushing provinces to enact a slew of public health measures and restrictions.
Single-layer cloth masks not effective against Omicron, says Ontario science advisory table director
Juni’s recommendation to ditch single-layer cloth face masks comes amid a call by some public health experts to re-examine masking guidelines, and more actively encourage the use of respirators and medical masks over cloth ones.
Colin Furness, an epidemiologist at the University of Toronto, said public health authorities need to more strongly encourage the use of KN95 respirators in indoor public settings.
Furness told the Canadian Press any campaign to push for their use should include resources to help Canadians find respirators that fit best.
“That’s public education we desperately need,” said Furness. “The fact that people are on their own for this is a travesty.”
2:10 Single-cloth masks not effective against Omicron, head of Ontario science table says
In November, the Public Health Agency of Canada (PHAC) updated its guidelines on mask use, suggesting respirators such as the KN95 are more effective than non-medical masks.
“In general, while non-medical masks can help prevent the spread of COVID-19, medical masks and respirators provide better protection,” said PHAC on their mask information webpage.
The agency also recommended the use of medical masks or respirators for those in vulnerable at-risk groups, or who run a higher risk of contracting COVID-19 within their work or living situation.
In a press conference Friday, Canada’s Chief Public Health Officer Dr. Theresa Tam also stressed Canadians to follow PHAC’s updated guidance on indoor ventilation and “proper use, construction and fit of face masks.”
READ MORE: Omicron FAQ: Everything you need to know about the COVID-19 variant
While respirators seem to be the consensus among public health experts and officials as the gold standard for protection against Omicron, they are quick to point out the added protection offered by respirators is very much dependent on the masks being properly fitted to a person’s face.
It’s a detail that Dr. Gerald Evans, chair of infectious diseases at Queen’s University, was quick to point out.
“The amount of extra protection you get from an N95 respirator … if it’s not fit-tested, is only marginally better than a medical mask,” said Evans.
While there is an upside to the protection offered by respirators if they are properly fitted, Evans also pointed out the high cost to regularly acquire them, as well as a lack of definitive evidence that N95s prevent transmission in community settings, more so than more cheaply produced medical masks
“So there’s no study that shows wearing an N95 statistically or clinically reduces the transmission of COVID 19 — more than a medical mask,” said Evans. “In fact, we have pretty good evidence, medical masks clearly work by reducing the overall infectious dose.”
1:17 COVID-19: WHO warns of dismissing the Omicron variant as being ‘mild’, calls for stronger measures
In differing guidance towards what looks to be general public use of masks, PHAC said a “respirator worn in the community doesn’t need to have been formally fit-tested as is required in some occupational settings.”
Evans also said the increased transmission of Omicron is not because it’s “more airborne” — a virus’ trait from which a respirator could further protect users. Rather, he said, people with the variant begin shedding higher loads of the virus, due to it replicating rapidly in the cells it infects.
The bottom line from Evans though is: “If you have a lot of money and you can afford an N95 mask or one of those equivalents, go ahead and buy them.”
\
“But if you can, get a medical mask — they’re not very expensive … and if you can’t afford that, but you’ve got some good cloth masks, use them, don’t forget to clean them and probably think about double-masking if you think that’s appropriate.”
— With files from The Canadian Press
More protective masking, including N95s, needed to curb Omicron, say experts
Adina Bresge
Adina Bresge
The Canadian Press
Saturday, December 18, 2021
TORONTO -- When Linsey Marr boarded a bus in Lake Louise, Alta., earlier this week, she was floored to find out that she had to take off her N95 respirator and put on a medical mask for the ride.
The Virginia Tech engineering professor, who studies viruses in the air, said the policy defies scientific reason, because respirators offer far more protection than a medical mask, both to the wearer and others around them.
"It would be like asking someone to take off their seatbelt, and to use this piece of rope to tie themselves to the seat instead," Marr said by phone.
A number of Canadians responded to her tweet about the incident saying they'd run into similar resistance while wearing respirators at hospitals and other health-care settings.
Experts say policies prohibiting N95 use are a step in the wrong direction when more protective masking is crucial to curbing the spread of the Omicron variant of COVID-19.
"It's even more critical now to protect yourself and others that we wear high-performance masks, which means they filter out particles well, and they fit well," said Marr, noting that while N95s are an effective option, she doesn't think they should be mandated in all situations.
Both medical masks and respirators are made out of materials that can filter out particles of all sizes, said Marr. The main difference comes down to fit -- respirators are designed to form a seal around the face, while medical masks often leave gaps under the cheeks or chin that allow very small particles to seep through.
These leaks lead to significantly less protection against the novel coronavirus, she said. A well-fitted respirator offers more than 95 per cent protection, she said. For medical masks, effectiveness ranges from 20 per cent to 90 per cent depending on how snug it is.
If hospitals or other facilities want to standardize what masks people wear because of concerns about quality control and counterfeits, Marr offered a simple solution: either let people wear a medical mask over their respirators, or offer everyone a N95.
On Friday, Ontario's chief medical officer of health issued an interim guidance requiring that all medical workers wear N95s when providing direct care to possible or confirmed COVID-19 patients.
Under the previous directive, health workers were allowed to wear medical masks unless it was determined that there was an elevated risk of infection, such as during procedures that generate small airborne viral particles.
The move was in line with Public Health Ontario's revised recommendations on personal protective equipment for health workers, which recognize N95s as an acceptable alternative to medical masks under certain circumstances, including for people visiting patient rooms and long-term care homes.
The agency said in an email that evidence published before the emergence of Omicron did not support the use of N95s over medical masks to protect health workers against COVID-19. But until more is known about the new variant, "it is prudent to enhance all layers of protection," the agency said.
The Public Health Agency of Canada also updated its mask recommendations in November amid growing consensus that small airborne particles play a significant role in spreading the novel coronavirus, in a departure from previous messaging pointing to larger respiratory droplets as the main mode of transmission.
The guidelines endorse the use of respirators among the general public, noting that they may provide a better fit than medical or non-medical masks.
Colin Furness, a University of Toronto infection control epidemiologist, said health authorities need to go further to encourage the use of N95 respirators across indoor public settings.
This campaign should include efforts to help Canadians identify the type of respirator that best fits their face, he said, likening the process to trying on the right pair of jeans.
"That's public education we desperately need," he said. "The fact that people are on their own for this is a travesty."
Mask messaging needs to reflect our evolving understanding of the novel coronavirus, said Furness.
Medical masks are effective at trapping droplets before they spread to others, he said. But as the Omicron variant has underscored the threat of airborne transmission, Furness said the emphasis needs to be on promoting respirators as a means of self-protection.
"You need to wear a mask defensively," he said. "N95s are the tool for the job."
Saturday, December 18, 2021
TORONTO -- When Linsey Marr boarded a bus in Lake Louise, Alta., earlier this week, she was floored to find out that she had to take off her N95 respirator and put on a medical mask for the ride.
The Virginia Tech engineering professor, who studies viruses in the air, said the policy defies scientific reason, because respirators offer far more protection than a medical mask, both to the wearer and others around them.
"It would be like asking someone to take off their seatbelt, and to use this piece of rope to tie themselves to the seat instead," Marr said by phone.
A number of Canadians responded to her tweet about the incident saying they'd run into similar resistance while wearing respirators at hospitals and other health-care settings.
Experts say policies prohibiting N95 use are a step in the wrong direction when more protective masking is crucial to curbing the spread of the Omicron variant of COVID-19.
"It's even more critical now to protect yourself and others that we wear high-performance masks, which means they filter out particles well, and they fit well," said Marr, noting that while N95s are an effective option, she doesn't think they should be mandated in all situations.
Both medical masks and respirators are made out of materials that can filter out particles of all sizes, said Marr. The main difference comes down to fit -- respirators are designed to form a seal around the face, while medical masks often leave gaps under the cheeks or chin that allow very small particles to seep through.
These leaks lead to significantly less protection against the novel coronavirus, she said. A well-fitted respirator offers more than 95 per cent protection, she said. For medical masks, effectiveness ranges from 20 per cent to 90 per cent depending on how snug it is.
If hospitals or other facilities want to standardize what masks people wear because of concerns about quality control and counterfeits, Marr offered a simple solution: either let people wear a medical mask over their respirators, or offer everyone a N95.
On Friday, Ontario's chief medical officer of health issued an interim guidance requiring that all medical workers wear N95s when providing direct care to possible or confirmed COVID-19 patients.
Under the previous directive, health workers were allowed to wear medical masks unless it was determined that there was an elevated risk of infection, such as during procedures that generate small airborne viral particles.
The move was in line with Public Health Ontario's revised recommendations on personal protective equipment for health workers, which recognize N95s as an acceptable alternative to medical masks under certain circumstances, including for people visiting patient rooms and long-term care homes.
The agency said in an email that evidence published before the emergence of Omicron did not support the use of N95s over medical masks to protect health workers against COVID-19. But until more is known about the new variant, "it is prudent to enhance all layers of protection," the agency said.
The Public Health Agency of Canada also updated its mask recommendations in November amid growing consensus that small airborne particles play a significant role in spreading the novel coronavirus, in a departure from previous messaging pointing to larger respiratory droplets as the main mode of transmission.
The guidelines endorse the use of respirators among the general public, noting that they may provide a better fit than medical or non-medical masks.
Colin Furness, a University of Toronto infection control epidemiologist, said health authorities need to go further to encourage the use of N95 respirators across indoor public settings.
This campaign should include efforts to help Canadians identify the type of respirator that best fits their face, he said, likening the process to trying on the right pair of jeans.
"That's public education we desperately need," he said. "The fact that people are on their own for this is a travesty."
Mask messaging needs to reflect our evolving understanding of the novel coronavirus, said Furness.
Medical masks are effective at trapping droplets before they spread to others, he said. But as the Omicron variant has underscored the threat of airborne transmission, Furness said the emphasis needs to be on promoting respirators as a means of self-protection.
"You need to wear a mask defensively," he said. "N95s are the tool for the job."
PUBLIC HEALTH
Why We Need to Upgrade Our Face Masks—and Where to Get Them
High-quality respirators such as N95s and KN95s are now widely available and provide the best protection against COVID, according to experts. Why aren’t more people wearing them?
By Tanya Lewis
WHAT MAKES A GOOD MASK?
When it comes to mask effectiveness, the most important parameters are filtration, fit and comfort. Filtration generally refers to the percentage of particles the mask material blocks. For example, an N95 filters at least 95 percent of airborne particles. But that does little good if gaps around the mask let air in freely. A well-fitted mask should sit snugly against the face and over the chin, with no gaps around the nose or mouth. Comfort is also an extremely important metric: a mask does no good if people simply find it intolerable to wear.
A good mask is “the most important defense we have” against COVID, says aerosol expert Kimberly Prather, an atmospheric chemist at the University of California, San Diego.
There are a number of national standards for respirator quality. The U.S. gold standard, N95s, are certified by the CDC’s National Institute for Occupational Safety and Health (NIOSH). And the Occupational Safety and Health Administration (OSHA) sets standards for how they have to fit people in work settings (such as in hospitals). But there is no official standard for N95 use by the general public. The European equivalent of the N95 is the FFP2 respirator, which filters at least 94 percent of particles. China has the KN95, and South Korea has the KF94. All provide excellent filtration, so it really comes down to which fits an individual best and is most comfortable.
WHICH MASKS ARE BEST?
In the absence of more specific guidance from health authorities such as the CDC as to which brands of respirators and other masks provide the best protection, some skilled amateurs have stepped in to fill the gap. Aaron Collins, aka “Mask Nerd,” is a mechanical engineer at Seagate Technology with a background in aerosol science. In his free time, he makes YouTube videos in which he tests and reviews high-filtration masks made by various manufacturers. Collins says he does not earn any money from mask manufacturers or his videos themselves—he considers them a service and wants them to be objective.
Collins has a mask-testing setup in his bathroom, where he assesses masks’ filtration efficiency by generating aerosols of sodium chloride (salt). He then uses a condensation particle counter—a device that measures the concentration of particles inside and outside a mask he is wearing—to determine the total inward leakage through and around the mask. (For comparison, NIOSH’s N95 standard requires manufacturers to measure leakage through the respirator material itself. And OSHA measures how a respirator fits on someone’s face, which often involves wearing an N95 in an enclosed space with saccharin or another distinctly flavored test aerosol sprayed in: if the wearer reports tasting the substance, the mask fails the fit test.)
Collins also tests “pressure drop,” which is basically how easy it is to breathe while wearing a mask. If doing so is too difficult, a wearer might not only find the mask less comfortable but also suck in air around its sides, negating its filtration. Some cloth masks—including those outfitted with coffee filters—have this problem. “There’s a reason N95s aren’t made from cloth,” Collins says.
The Mask Nerd’s top picks can be found in this video. In general, he recommends KN95s made by Chinese company Powecom and others, a variety of KF94s such as the Bluna FaceFit and N95s made by reputable brands such as 3M, Moldex or Honeywell. All of these masks had close to 99 percent filtration efficiencies and fairly low pressure drops in Collins’s setup. (For comparison, he found that a surgical mask alone had between about 50 and 75 percent filtration efficiency, depending on the fit, and a good cloth mask had about 70 percent.) But when choosing the best mask, comfort should be a deciding factor, he says. Not everyone needs to wear an N95.
“To me, the minimum I want to see people wear is a KN95 or KF94 with the Delta variant,” Collins says. “I don’t think surgical masks are good enough anymore, and we should’ve gotten rid of cloth masks last summer—they’re not even in the spectrum” of good filtration. (To be clear, some studies have found that surgical and cloth masks can provide at least some protection against COVID. A recent large, randomized study in Bangladesh found that surgical masks significantly lowered the risk of infection; cloth masks did not have a measurable benefit, although other studies suggest they provide some protection.)
THE BEST MASKS FOR KIDS
With children starting school in-person, many parents are understandably worried about their kids, especially those who are too young to be eligible for vaccination—and particularly in states where politicians have tried to ban mask mandates in schools. These parents might find Collins’s recommendations for high-filtration kids’ masks particularly helpful. There is no N95 standard for children, but plenty of manufacturers make KF94 or KN95 masks for them. Such masks are designed for small faces and are easy to put on. Collins sees no reason why kids could not tolerate them. “I have my own son,” Collins says. “He’s five years old. He wore them all summer.”
WHERE TO FIND LEGITIMATE MASKS
An issue with commercially available high-filtration masks is that they may not come from reputable suppliers. The CDC’s Web site warns that about 60 percent of KN95 respirators available in the U.S. are counterfeit. To find ones that are legitimate, Prather recommends the Web site Project N95. Masks can also be ordered directly from suppliers such as Bona Fide Masks, which sells KN95s made by Powecom. “That’s the one people swear by,” Prather says. They cost around $1 each. DemeTECH sells N95s for around $4 apiece, as well as other types of masks.
REUSING MASKS
One reason people may be reluctant to use KN95s and similar masks is because they are usually considered disposable. But several experts say they can in fact be worn multiple times. “You can probably reuse it until it becomes visibly damaged or soiled,” Marr says. Collins’s amateur testing suggests mask can be used for up 40 hours with no decrease in their filtration efficacy (he recommends using them within six months of opening a package). The virus likely does not survive long on these masks, but it is not a bad idea to have a few in rotation, reusing one every three days or so, Collins says.
DOUBLE MASKING
One popular way to increase effectiveness is to wear a cloth mask on top of a surgical mask. This strategy, which the CDC has recommended, combines the filtration efficiency of the surgical mask material with the fit of a cloth mask. But how well does it actually work?
According to Collins, pretty well. He measured a filtration efficiency of upward of 90 percent for a cloth mask (with nose wire) over a surgical mask. But the pressure drop was almost twice as high as that of an N95. One reason the CDC and others have recommended against the use of N95s by the general public, apart from their previous scarcity, is that they can be difficult to breathe through—so Collins finds it “baffling” that the CDC would recommend double masking. “So does double masking work? Yes, but … I think there are better solutions,” he said in one of his videos.
Another way to get a better fit is to use masks with straps that go around the back of the head or to use a mask brace if one only has access to a surgical mask.
Not all experts agree that high-filtration masks are necessary for everyone. “What I usually say is ‘The best mask is the one you wear properly,’” says Judith Flores, a pediatrician and a fellow of the American Academy of Pediatrics and of the New York Academy of Medicine. Flores believes surgical masks are the most convenient and cleanest option if they are discarded after each use. Cloth masks are okay, too, she adds, as long as they have three layers. “Unless you are a health care worker or home care worker tending to a person who is COVID-positive,” Flores says, “you don’t need an N95.”
FACIAL HAIR
What about the bewhiskered among us? How does facial hair influence the effectiveness of various masks? While there are not a great deal of data on this, some research suggests that the longer a person’s beard or mustache is, the less effective a mask will be because it makes an inferior seal with the face. The CDC has released a somewhat amusing graphic demonstrating styles of facial hair that are appropriate to wear with a respirator.
At this point in the pandemic, with supplies of high-quality masks readily available in many areas, perhaps it is time to ditch loose-fitting cloth or surgical masks for something that provides better protection. “The most important layer of protection,” Prather says, “is to never let the virus get out in the air in the first place.”
ABOUT THE AUTHOR(S)
Tanya Lewis is a senior editor at Scientific American who covers health and medicine. Follow Tanya Lewis on Twitter Credit: Nick Higgins
READ THIS NEXT
PUBLIC HEALTH
COVID, Quickly, Episode 14: Best Masks, Explaining Mask Anger, Biden's New Plan
Josh Fischman, Tanya Lewis and Jeffery DelViscio
PUBLIC HEALTH
Masks Protect Schoolkids from COVID despite What Antiscience Politicians Claim
EPIDEMIOLOGY
Masks Are a Must-Have to Go Back to School during the Delta Variant Surge
PUBLIC HEALTH
How to Use Masks during the Coronavirus Pandemic
Why We Need to Upgrade Our Face Masks—and Where to Get Them
High-quality respirators such as N95s and KN95s are now widely available and provide the best protection against COVID, according to experts. Why aren’t more people wearing them?
By Tanya Lewis
on September 30, 2021
KN95 face mask. Credit: Getty Images
A wealth of evidence has shown that wearing a face mask helps prevent people from spreading the virus that causes COVID, SARS-CoV-2, to others and from becoming sick themselves. But there has been less guidance from public health officials on what kind of masks provide the best protection.
Early on in the pandemic, the U.S. Centers for Disease Control and Prevention and the World Health Organization told the public not to wear N95 respirators, a type of mask that is made from high-tech synthetic fibers and provides a high level of protection against virus-laden airborne particles called aerosols. That was because there was then a shortage of such masks—and health care workers desperately needed them. At the same time, both agencies said there was little risk of aerosol transmission of SARS-CoV-2. They recommended cloth masks or other homemade face coverings that can stop some relatively large virus-carrying droplets even as it became clear that SARS-CoV-2 commonly spreads through aerosols—and as the supply of better-quality masks increased.
There is now a cornucopia of high-filtration respirator-style masks on the market, including N95s, Chinese-made KN95s and South Korean–made KF94s. They have been widely available and relatively affordable for months and provide better protection than cloth or surgical masks. Yet it was not until September 10 that the CDC finally updated its guidance to say the general public could wear N95s and other medical-grade masks now that they are in sufficient supply.
Still, however, the “CDC continues to recommend that N95 respirators should be prioritized for protection against COVID-19 in healthcare settings,” wrote CDC spokesperson Jade Fulce in an e-mail to Scientific American last week. “Essential workers and workers who routinely wore respirators before the pandemic should continue wearing N95 respirators,” she continued. “As N95s become more available they can be worn in non-healthcare settings, however, cloth masks are an acceptable and recommended option for masking.”
The agency announced in May that supplies of approved respirator masks had “increased significantly.” When asked why it only updated it guidance on N95 use by the public in September, Fulce replied that the “CDC regularly reviews and updates its guidance as more information becomes available.”
Scientific American spoke with several experts on aerosol transmission—some of whom have tested various masks available on the market—and they agree that health authorities should strongly recommend people wear well-fitted, high-filtration masks.
“A year ago we could say that we were concerned about shortages for health care workers, so we were telling people to make your cloth mask, and any mask is better than no mask,” says Linsey Marr, an environmental engineer and aerosol science expert at Virginia Tech. But given what scientists know now—especially with the virus’s highly transmissible Delta variant spreading and people spending more time indoors in schools, for example—“I think the CDC should be recommending high-performance masks for everyone when they’re in these risky indoor situations,” she says.
A wealth of evidence has shown that wearing a face mask helps prevent people from spreading the virus that causes COVID, SARS-CoV-2, to others and from becoming sick themselves. But there has been less guidance from public health officials on what kind of masks provide the best protection.
Early on in the pandemic, the U.S. Centers for Disease Control and Prevention and the World Health Organization told the public not to wear N95 respirators, a type of mask that is made from high-tech synthetic fibers and provides a high level of protection against virus-laden airborne particles called aerosols. That was because there was then a shortage of such masks—and health care workers desperately needed them. At the same time, both agencies said there was little risk of aerosol transmission of SARS-CoV-2. They recommended cloth masks or other homemade face coverings that can stop some relatively large virus-carrying droplets even as it became clear that SARS-CoV-2 commonly spreads through aerosols—and as the supply of better-quality masks increased.
There is now a cornucopia of high-filtration respirator-style masks on the market, including N95s, Chinese-made KN95s and South Korean–made KF94s. They have been widely available and relatively affordable for months and provide better protection than cloth or surgical masks. Yet it was not until September 10 that the CDC finally updated its guidance to say the general public could wear N95s and other medical-grade masks now that they are in sufficient supply.
Still, however, the “CDC continues to recommend that N95 respirators should be prioritized for protection against COVID-19 in healthcare settings,” wrote CDC spokesperson Jade Fulce in an e-mail to Scientific American last week. “Essential workers and workers who routinely wore respirators before the pandemic should continue wearing N95 respirators,” she continued. “As N95s become more available they can be worn in non-healthcare settings, however, cloth masks are an acceptable and recommended option for masking.”
The agency announced in May that supplies of approved respirator masks had “increased significantly.” When asked why it only updated it guidance on N95 use by the public in September, Fulce replied that the “CDC regularly reviews and updates its guidance as more information becomes available.”
Scientific American spoke with several experts on aerosol transmission—some of whom have tested various masks available on the market—and they agree that health authorities should strongly recommend people wear well-fitted, high-filtration masks.
“A year ago we could say that we were concerned about shortages for health care workers, so we were telling people to make your cloth mask, and any mask is better than no mask,” says Linsey Marr, an environmental engineer and aerosol science expert at Virginia Tech. But given what scientists know now—especially with the virus’s highly transmissible Delta variant spreading and people spending more time indoors in schools, for example—“I think the CDC should be recommending high-performance masks for everyone when they’re in these risky indoor situations,” she says.
WHAT MAKES A GOOD MASK?
When it comes to mask effectiveness, the most important parameters are filtration, fit and comfort. Filtration generally refers to the percentage of particles the mask material blocks. For example, an N95 filters at least 95 percent of airborne particles. But that does little good if gaps around the mask let air in freely. A well-fitted mask should sit snugly against the face and over the chin, with no gaps around the nose or mouth. Comfort is also an extremely important metric: a mask does no good if people simply find it intolerable to wear.
A good mask is “the most important defense we have” against COVID, says aerosol expert Kimberly Prather, an atmospheric chemist at the University of California, San Diego.
There are a number of national standards for respirator quality. The U.S. gold standard, N95s, are certified by the CDC’s National Institute for Occupational Safety and Health (NIOSH). And the Occupational Safety and Health Administration (OSHA) sets standards for how they have to fit people in work settings (such as in hospitals). But there is no official standard for N95 use by the general public. The European equivalent of the N95 is the FFP2 respirator, which filters at least 94 percent of particles. China has the KN95, and South Korea has the KF94. All provide excellent filtration, so it really comes down to which fits an individual best and is most comfortable.
WHICH MASKS ARE BEST?
In the absence of more specific guidance from health authorities such as the CDC as to which brands of respirators and other masks provide the best protection, some skilled amateurs have stepped in to fill the gap. Aaron Collins, aka “Mask Nerd,” is a mechanical engineer at Seagate Technology with a background in aerosol science. In his free time, he makes YouTube videos in which he tests and reviews high-filtration masks made by various manufacturers. Collins says he does not earn any money from mask manufacturers or his videos themselves—he considers them a service and wants them to be objective.
Collins has a mask-testing setup in his bathroom, where he assesses masks’ filtration efficiency by generating aerosols of sodium chloride (salt). He then uses a condensation particle counter—a device that measures the concentration of particles inside and outside a mask he is wearing—to determine the total inward leakage through and around the mask. (For comparison, NIOSH’s N95 standard requires manufacturers to measure leakage through the respirator material itself. And OSHA measures how a respirator fits on someone’s face, which often involves wearing an N95 in an enclosed space with saccharin or another distinctly flavored test aerosol sprayed in: if the wearer reports tasting the substance, the mask fails the fit test.)
Collins also tests “pressure drop,” which is basically how easy it is to breathe while wearing a mask. If doing so is too difficult, a wearer might not only find the mask less comfortable but also suck in air around its sides, negating its filtration. Some cloth masks—including those outfitted with coffee filters—have this problem. “There’s a reason N95s aren’t made from cloth,” Collins says.
The Mask Nerd’s top picks can be found in this video. In general, he recommends KN95s made by Chinese company Powecom and others, a variety of KF94s such as the Bluna FaceFit and N95s made by reputable brands such as 3M, Moldex or Honeywell. All of these masks had close to 99 percent filtration efficiencies and fairly low pressure drops in Collins’s setup. (For comparison, he found that a surgical mask alone had between about 50 and 75 percent filtration efficiency, depending on the fit, and a good cloth mask had about 70 percent.) But when choosing the best mask, comfort should be a deciding factor, he says. Not everyone needs to wear an N95.
“To me, the minimum I want to see people wear is a KN95 or KF94 with the Delta variant,” Collins says. “I don’t think surgical masks are good enough anymore, and we should’ve gotten rid of cloth masks last summer—they’re not even in the spectrum” of good filtration. (To be clear, some studies have found that surgical and cloth masks can provide at least some protection against COVID. A recent large, randomized study in Bangladesh found that surgical masks significantly lowered the risk of infection; cloth masks did not have a measurable benefit, although other studies suggest they provide some protection.)
THE BEST MASKS FOR KIDS
With children starting school in-person, many parents are understandably worried about their kids, especially those who are too young to be eligible for vaccination—and particularly in states where politicians have tried to ban mask mandates in schools. These parents might find Collins’s recommendations for high-filtration kids’ masks particularly helpful. There is no N95 standard for children, but plenty of manufacturers make KF94 or KN95 masks for them. Such masks are designed for small faces and are easy to put on. Collins sees no reason why kids could not tolerate them. “I have my own son,” Collins says. “He’s five years old. He wore them all summer.”
WHERE TO FIND LEGITIMATE MASKS
An issue with commercially available high-filtration masks is that they may not come from reputable suppliers. The CDC’s Web site warns that about 60 percent of KN95 respirators available in the U.S. are counterfeit. To find ones that are legitimate, Prather recommends the Web site Project N95. Masks can also be ordered directly from suppliers such as Bona Fide Masks, which sells KN95s made by Powecom. “That’s the one people swear by,” Prather says. They cost around $1 each. DemeTECH sells N95s for around $4 apiece, as well as other types of masks.
REUSING MASKS
One reason people may be reluctant to use KN95s and similar masks is because they are usually considered disposable. But several experts say they can in fact be worn multiple times. “You can probably reuse it until it becomes visibly damaged or soiled,” Marr says. Collins’s amateur testing suggests mask can be used for up 40 hours with no decrease in their filtration efficacy (he recommends using them within six months of opening a package). The virus likely does not survive long on these masks, but it is not a bad idea to have a few in rotation, reusing one every three days or so, Collins says.
DOUBLE MASKING
One popular way to increase effectiveness is to wear a cloth mask on top of a surgical mask. This strategy, which the CDC has recommended, combines the filtration efficiency of the surgical mask material with the fit of a cloth mask. But how well does it actually work?
According to Collins, pretty well. He measured a filtration efficiency of upward of 90 percent for a cloth mask (with nose wire) over a surgical mask. But the pressure drop was almost twice as high as that of an N95. One reason the CDC and others have recommended against the use of N95s by the general public, apart from their previous scarcity, is that they can be difficult to breathe through—so Collins finds it “baffling” that the CDC would recommend double masking. “So does double masking work? Yes, but … I think there are better solutions,” he said in one of his videos.
Another way to get a better fit is to use masks with straps that go around the back of the head or to use a mask brace if one only has access to a surgical mask.
Not all experts agree that high-filtration masks are necessary for everyone. “What I usually say is ‘The best mask is the one you wear properly,’” says Judith Flores, a pediatrician and a fellow of the American Academy of Pediatrics and of the New York Academy of Medicine. Flores believes surgical masks are the most convenient and cleanest option if they are discarded after each use. Cloth masks are okay, too, she adds, as long as they have three layers. “Unless you are a health care worker or home care worker tending to a person who is COVID-positive,” Flores says, “you don’t need an N95.”
FACIAL HAIR
What about the bewhiskered among us? How does facial hair influence the effectiveness of various masks? While there are not a great deal of data on this, some research suggests that the longer a person’s beard or mustache is, the less effective a mask will be because it makes an inferior seal with the face. The CDC has released a somewhat amusing graphic demonstrating styles of facial hair that are appropriate to wear with a respirator.
At this point in the pandemic, with supplies of high-quality masks readily available in many areas, perhaps it is time to ditch loose-fitting cloth or surgical masks for something that provides better protection. “The most important layer of protection,” Prather says, “is to never let the virus get out in the air in the first place.”
ABOUT THE AUTHOR(S)
Tanya Lewis is a senior editor at Scientific American who covers health and medicine. Follow Tanya Lewis on Twitter Credit: Nick Higgins
READ THIS NEXT
PUBLIC HEALTH
COVID, Quickly, Episode 14: Best Masks, Explaining Mask Anger, Biden's New Plan
Josh Fischman, Tanya Lewis and Jeffery DelViscio
PUBLIC HEALTH
Masks Protect Schoolkids from COVID despite What Antiscience Politicians Claim
EPIDEMIOLOGY
Masks Are a Must-Have to Go Back to School during the Delta Variant Surge
PUBLIC HEALTH
How to Use Masks during the Coronavirus Pandemic
No comments:
Post a Comment