Canada's mask guidance has changed. Here's why you might need an upgrade

Now that the cold weather has hit and people aremoving inside, many doctors and scientistsare urging Canadians not only to resist gettingcomplacent about wearing masks to protect against COVID-19 but also to take a closer look at whether that cloth mask is keeping you and others as safe as possible.

"In general, while non-medical masks can help prevent the spread of COVID-19, medical masks and respirators provide better protection," the Public Health Agency of Canada (PHAC) saidon its COVID-19 mask information webpage, which was updated on Nov. 12.

The updated guidance also recommends medical masks or respirators for people "who are at risk of more severe disease or outcomes from COVID-19" andthose "at higher risk of exposure to COVID-19 because of their living situation."

Respirators (such asN-95 and KN-95 masks)are considered the highest level of mask protection andwere previouslyrecommended only for health-care workers coming into direct contact with infectious patients. In those high-risk areas, respirators require a "fit test."

But in a nod to more general use, PHAC's guidance now says:"Arespirator worn in the community doesn't need to have been formally fit testedas is required in some occupational settings."

Responding to a CBC News inquiry about why PHAC's recommendations have changed, the agency said in an email it was "based on the latest scientific evidence on SARS-CoV-2 virus variants of concern, increased understanding of the impacts of vaccination and immunity in the population, and new data available on mask types and their effectiveness."

In addition to the updated online guidance, Dr. Theresa Tam, Canada's chief public health officer,recently posted a series of tweets illustrating how COVID-19 couldspread through the air, using the analogy of second-hand smoke.

Many doctors, scientists and engineers say thisshift in messagingreflects a growing body of evidence suggesting that COVID-19 is largely spread through aerosols (tiny particles that can hang in the air), and not just through respiratory droplets (larger particles)transmitted by closecontact with an infected person.

In turn, that means it's important to re-evaluate the masks we're using, they say.

"This marks a transition in Canada towarda recognition of how important aerosol, airborne-basedtransmission is in transmission of this virus," said Dr. Brooks Fallis, a critical care physician at the Toronto-area William Osler Health System.

Because aerosol particles are smaller and can accumulate in the air over time,Fallis said, the best-performing masks are critical if you're going to be indoors with other people for a while.

"If you're just, you know,popping into the grocery store to grab a couple of items, or you're walking along a crowded street and you want to wear a mask, then it's fine [to wear a medicalmask]," Fallis said.

"But if you're in a closed space with lots of people, then we should be upgrading to higher-level masks, like theKN-95 masks or a respirator-type mask, which provides better fit and better filtration."

Masks are important even when you're fully vaccinated, both PHAC and doctors say, because although it's much less likely, infection with the virus that causes COVID-19 especially the highly transmissible delta variant can still happen.

Better availability of higher-grade masks

Anotherimportant factor that's changed since the beginning of the pandemic, experts say, is the availability of medical/surgical masks and respirators.

"There was a lot of controversy about N-95 masks because there weren't enough for the health-care workers. So the message then, quite understandably, was:'Save those for the health-care workers and we will use other alternatives,'" saidMarianne Levitsky, an industrial hygienist with the Dalla Lana School of Public Health at the University of Toronto.

"But things have changed a lot. We now have Canadian manufacturers making N-95-type masksand they're much more widely available than they used to be," she said.

WATCH | Respirators are considered the highest level of mask protection:

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With more contagious variants of COVID-19 on the rise, theres more talk of improving peoples masks. The type of mask is important, but as The Nationals Andrew Chang found out, so is its fit.

Experts agreeany mask is better than no mask, because it will catch droplets and aerosols coming from the wearer's nose and mouth and protect others. But there's growing evidence that a higher-quality mask can also provide some protection for the wearer.

"The masks or respirators, they control in twoways. One, they can prevent an infected person from emitting those infectious aerosols into a space, and they can also protect the person who is wearing them from inhaling them," said Levitsky.

"Cloth masks were always sort of something that was going to buy us some time as we move towardsomething better," saidConor Ruzycki, a PhD candidate in mechanical engineering at the University of Albertawho studies aerosol science and technology.

"Now that we understand this disease better, we know that these small aerosols are playing a bigger role;we should be moving toward using better mask materials."

The 3 Fs of choosing a mask

There are three F-words to keep in mind when assessing how well a mask will protect you and others: Fit, filtration and function (also called breathability).

"Fit is essential in terms of how effective filtration happens in a real setting," saidRavi Selvaganapathy,a professor of biomedical engineering at theCentre of Excellence in Protective Equipment and Materials at McMaster University.

"You can have the best quality material out there, but if it doesn't fitone's face, then most of the air goes through these large gaps that exist and not through the filter material."

The filter material in both medical/surgical masks and N-95 respirators is actually the samebut respiratorscontour better to a person's face, saidSelvaganapathy.

A "knot and tuck" adjustmentcan improve the fit of disposable masks including medical masks, theCenters for Disease Control and Prevention (CDC) advises.

"Knot the earloops of a three-ply face mask where they join the edge of the mask," the CDC website says. "[Then] fold and tuck the unneeded material under the edges."

• Watch the CDC's video on how to knot and tuck your mask with earloops

Cloth masks oftenoffer good fit and good function (breathability),but how well they filter out virus particles is usually a wild card, experts say, because they're made of varyingmaterials and aren't regulated.

"There are no standards. When you buy a cloth mask, it does not usually tell you what the filtration is," Levitsky said.They can protect anywhere from 20 per cent to 80 per cent, she said."So it's a big unknown."

Filtrationformedical/surgical masks and respiratorsis graded by the standards organization ASTMInternational. And some non-cloth, non-medical masks available in stores may look like medical masksbut aren't,experts say, so it's important for consumers to check the label.

The ASTM has started a voluntary certification program for non-medical masks,but at this point, there aren't many certified non-medical masks available.

In an effort to better curb COVID-19 transmission, some countries, likeGermany and Austria,have mandated medical-grade masks and respirators instead of cloth masks in public areas.

In many cases, they've been distributed for free or subsidized, said Fallis a move he'd like to see Canada make.

"I think that's a worthwhile investment because it's another way to bring cases down [and]to make higher-quality masks a little bit cheaper, particularly to people [for whom] it's a financial burden to be purchasing masks," he said.