COVID-19 and masks: Infectious disease experts answer your questions

The debate over whether or not to wear a mask has been front and centre since the outset of the COVID-19 pandemic.

In early weeks, the consensus among health officials was that they were unnecessary — and even potentially dangerous if worn incorrectly.

As the science has evolved, things have changed dramatically. Now a growing number of cities and regions in the country are making masks mandatory in indoor public settings to control the spread of the coronavirus.

Infectious disease experts Dr. Susy Hota and Colin Furness took mask-related questions from the Checkup audience and guest host David Common. Here are some of their answers.

Should wearing a mask indoors be mandatory?

Dr. Hota, agreed that masks should be made mandatory in indoor public settings, as has recently been affirmed by cities like Toronto and Ottawa.

Hota — an infectious disease physician, clinician, and director at the University Health Network in Toronto — told Common that in the early days of the pandemic, researchers lacked evidence that showed masks slowed the spread of the virus.

"But I feel like the science has changed. Our understanding of the virus and how it transmits has changed," she said.

Furness, an infection control epidemiologist and an assistant professor at the University of Toronto, said that in addition to protecting people, a mandatory mask law can serve as "a mnemonic" to remind people of the importance of maintaining public health and safety.

"I think that face coverings has two purposes. It's maintaining or keeping your droplets close to you, but also serving as a constant reminder that we have to be vigilant," he said.

Should masks be worn outside?

Common said he's seen many people outside taking a walk or riding a bicycle while wearing a mask. Furness, however, said that it's usually best to keep them off until you go indoors, as the wind helps disperse people's mouth droplets.

"To put it another way, it's pretty hard to tell who's got bad breath when you're outdoors. And that's because the air currents get in the way," he said.

He elaborated that masks are most useful when people are indoors with shared air, and that wearing a mask for too long can contaminate their surfaces.

Why are masks only effective 'one way?'

Checkup listener Jim Priebe asked why masks are said to help people from spreading the virus to other people, but not the person wearing the mask.

Furness said that when you exhale, you expel relatively large droplets. "Those are the ones we're really worried about, because they're more likely to contain a lot of virus in them," he said.

"So you are exhaling small droplets through the mask, and you are inhaling small droplets through the mask. But a lot of what you exhale will stay close to you because of the mask."

Can I reuse my masks?

Several callers and commenters asked whether you can properly clean and reuse a homemade cloth mask, or a protective N95 mask.

Hota said that most cloth masks can be reused, but they have to be handled carefully to avoid contaminating them. She said people should try to touch the fastening elastic, rather than touching the fabric, and storing them in a plastic bag or plastic container.

She cautioned, however, that N95 masks are designed for professional use and are meant to be disposable.

"So I would say your cloth mask is a safer option, as long as you're using it correctly and cleaning it very regularly and frequently," she said.

How can I travel safely on a plane?

Jill from Edmonton sent an email asking what protections the doctors recommend for essential travel by airplane.

While Furness acknowledged that some people may not be able to avoid all air travel, he said he is "frightened" by it under current circumstances.

"There are people who are stuck next to each other … for a long period of time," he said.

He advised people to try obtaining a respirator mask for these conditions, and consider ponying up for a business class ticket, whose seats are more spaced out between travellers.

He also had stern words for the major Canadian airlines that have started selling middle seats again on their flights.

"I'm hoping Canadians turn their back on Air Canada and WestJet based on their decision to sell the middle seats because I think that makes it impossible to be safe in those circumstances," he said.

In May, the International Air Transport Association (IATA) trade group called for an end to in-flight physical distancing rules, proposing a range of measures including some that run counter to federal government policies.

Furness said he read the IATA report, calling its conclusions "absolutely unjustified" and that it lacked the backing of health professionals.

"They don't have an expert because, there won't be an expert who would stand up and say, 'Yes, that's OK,'" he said.

"I guess I would concede that we can't be certain what the risk level is. But I think at the very least, the precautionary principle applies, which is to say if we can't prove that it's safe, then we should assume that it isn't."

Written by Jonathan Ore with files from Kirthana Sasitharan.