Canada's Chief Medical Health Officer has gotten behind the use of non-medical masks.

Dr. Theresa Tam's position on the subject has changed twice before this since the COVID-19 pandemic reached Canada's shores.

In January, the advice from public health officials was that masks could provide a false sense of security. In March, that position changed to one saying that they could indeed help, but that there was no need for healthy people to wear them.

In April, it changed again; this time stating that a mask could protect others around you.

And finally, yesterday in a press conference, when Dr. Tam came out and recommended non-medical masks in public as an added layer of protection as provinces begin to reopen for business.

She says that the change in position comes as more information on how the virus is transmitted by asymptomatic and pre-symptomatic people becomes clearer.

"So if two people are wearing masks, I'm protecting you, and you are protecting me. So I think as more people do go out in the community, you can imagine there will be more people on public transport. Some of the retail stores are beginning to open for example, and if you can't predict whether you can maintain that 2-metre distance, then it's recommended."

She insists that that position isn't new, merely that the old recommendations were perhaps not clear enough.

"Particularly as people have generally been staying at home, and now that we're sort of reopening or restarting a lot of activities, the (provincial) chief medical officers felt that they can recommend this for people who cannot maintain that 2-metre distance."

When asked by a reporter why the federal government is holding at merely recommending non-medical masks rather than mandating their use, she answered that it was important for provincial health authorities to have that control since each of them would have vastly different COVID-19 experiences to this point.

"Comparing Montreal and Toronto to the Yukon or PEI might actually be very different. So they need the ability to make those recommendations. Their public transportation systems might be different, for example. And so they need the ability to do that risk assessment and recommend it from their perspective."

She added that where the federal government has authority, Transport Canada for example, they have made the wearing of non-medical masks mandatory.

At yesterday's daily press conference, Saskatchewan's Chief Medical Health Officer, Dr. Saqib Shahab, said that he saw no reason to echo the federal position, saying that Saskatchewan's present strategy is proving effective.

He added however, that in light of the federal recommendation that anyone that is asked by a business to wear a mask in order to enter should comply.