Dr. Tam says the fit of the mask is crucial; suggests to start wearing three layer non-medical masks

Canada's chief public health officer, Dr. Theresa Tam says the country has about 30,000 active cases of COVID-19 now.

She's making a pitch for Canadians wearing a non-medical mask to use three layers to further reduce the risk of spreading the virus to others.

Dr. Tam says nobody has really studied non-medical masks in the past and now there is more research into different materials, the number of layers and the fit.

Dr. Tam says the fit of the mask is crucial too, saying it should be pinched at the nose and must completely cover the mouth and nose.

But federal Health Minister Patty Hajdu says that doesn't mean two-layer masks are now useless.

The World Health Organization recommended wearing filtered, three-layer masks as early as June 12th, but Doctor Theresa Tam says opinions on face coverings evolve.