Your baggy mask isn't going to cut it against Omicron, epidemiologist warns

After almost two years of living with a pandemic, you would think we'd all be mask experts by now.

But the COVID-19 landscape is changing rapidly, and the things we thought would protect us are suddenly in need of a serious rethink — including, and perhaps especially, masks.

Those cloth and blue surgical masks so many of us have been wearing? They're unlikely to cut it against Omicron, says an expert.

We should all be upping our mask game immediately, warns epidemiology professor Dr. David Fisman of Toronto's Dalla Lana School of Public Health.

"To be honest, we should have been doing this for a while now," Fisman said in an interview with Shift NB, noting "we've known for over a year" that COVID-19 spreads through aerosol.

"And that's really important because that means people get infected by breathing in these tiny particles."

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Fisman used the mental image of COVID spreading like cigarette smoke.

If you think about how you would cope with being exposed to that, you might think about opening windows, using HEPA air filters and "protecting yourself with a well-fitting respirator to filter those tiny particles out," he said.

The key being "well-fitting."

Fisman said the commonly worn surgical masks and cloth masks are problematic because they're often "very baggy" around the sides.

What people should be wearing, he said, are sturdier, better-fitting masks that block and filter out infectious particles.

In other words, N95 masks.

"N95 masks, KN95 masks, CN95 masks ... those are respirators that are really fitted to your face," Fisman said.

"So they really are acting to filter out any particles in the air that you breathe. And we know they're very, very good at doing that."

'Baggy gaps' are the enemy

All masks work in two directions: protecting others by filtering out the aerosols in the breath of the wearer, and protecting the wearer by keeping aerosols exhaled by others from entering their respiratory system. 

The best cloth masks have several layers of different materials "and that can be a very effective filter," Fisman said.

The material that surgical masks are made of is also "very good at stopping those particles."

N95 masks, KN95 masks, CN95 masks ...  filter out any particles in the air that you breathe. And we know they're very, very good at doing that.- Dr. David Fisman, epidemiologist

But with both cloth masks and surgical masks, poor fit is the issue.

"The fit is everything. Mind the gap, as they say in the U.K.," Fisman said.

While N95 masks are more expensive than cloth or surgical masks, Fisman said they are more durable and can be worn more often than you might think.

For example, he said, the 3M-brand masks used in hospitals come with directions that say it should not be used twice.

"But that's not correct," he said. "The U.S. [Centers for Disease Control] says you can use them up to five times. The filter itself lasts for about 40 hours of 'on-face' time. So that filter is not going to give out first. If you keep the mask clean and look after it, what's going to give out first is probably the elastic. And then the mask will become baggy and you should throw it out." 

He also cautioned against buying cheap knockoff versions, noting there's "been a little bit of weird scammy stuff on Amazon with people selling counterfeit KN95 masks."