TORONTO -- The Public Health Agency of Canada has updated its recommendations on non-medical face masks with the country’s top doctor now suggesting Canadians wear coverings that are made of three layers including a filter.

Speaking at a press conference on Tuesday, Canada's Chief Public Health Officer Dr. Theresa Tam said adding what is called a filter layer to masks will provide Canadians with extra protection against COVID-19.

"This is an additional recommendation, just to add another layer of protection," Tam said.

As more research is conducted on the novel coronavirus, Tam said guidelines on how to best limit the spread of the virus has also evolved.

Tam said that masks with a filter will help trap small infectious particles and further protect against COVID-19. She said the degree of protection varies based on the construction, materials, and particularly the fit of non-medical masks.

"I keep emphasizing the fit is one of the most important things," she said. "It fits around your mouth, on your nose, and it has to cover your mouth and nose. So that's really important."

Tam stressed that Canadians currently using two-layered masks do not need to throw them in the trash, but should instead purchase a disposable filter to insert between the layers.

"We're not saying just throw out everything that you have. Nobody's really [done a] study on non-medical masks in the past so there's been actually more research into different materials," Tam said.

According to the Public Health Agency of Canada, a non-medical mask should be made of at least three layers, two of which should be tightly woven material fabric, such as cotton or linen. The third, middle layer should be a filter-type fabric, such as non-woven polypropylene fabric.

Reusable masks with a non-woven filter layer already built in should be washed daily, and can be washed multiple times. Those with disposable filters should be changed daily or as directed by the manufacturer, according to the updated guidelines.

When buying new face masks in the future, Tam said Canadians should look for those made with these three layers.

"Adding another layer of protection, I think, is particularly important right now as we're all moving inside," Tam said.

Infectious disease specialist Dr. Brian Conway told CTV News Channel that the updated recommendations will help deter Canadians from purchasing fashion-focused face masks that offer little protection.

"There are many fashion masks that are being made that don't cover the nose and don't cover the mouth, that don't have a way of being fitted closely to the face," Conway explained in an interview on Tuesday.

"This is more a reaction against that than against the very good two-layer mask we still have."

Conway agreed with Tam that the extra layer of protection is critical as the weather turns colder and more Canadians spend their time indoors.

While there is limited studies on the effectiveness three-layered masks compared to those with two layers, Conway said face coverings with a filter will provide better protection against possible transmission through smaller, aerosol droplets.

"It's really a call to action for all of us. If you buy a mask, if a three-layer mask is available, I think that's probably preferable. But again, good two layer masks have served us so well over the past several months," he said.

Despite the difference in layers, Conway said that Canadians do not have to disregard the masks they have been using until now. He stressed a two-layer mask is still effective if it fits as closely as possible against the face.

"Please wear them properly, please change them frequently and make sure that you have a mask on your person at all times," Conway said.

The new recommendation on face masks comes on the heels of Prime Minister Justin Trudeau warning that the window to control the second wave of the pandemic is "closing fast" as Canada’s cases continue to surge.

Trudeau again pleaded with Canadians on Tuesday to limit their contacts to what is "absolutely essential," download the COVID-19 Alert app, wear a face mask and practice good hand hygiene to help control the rise in infections.

"We have to work together -- right now -- to beat the second wave. It won’t be easy, but I know we can do it," Trudeau said.