VANCOUVER -- B.C.'s not alone in seeing a surge in COVID-19 cases, and one local doctor says there are important changes in the country's guidelines that everyone should be aware of.

Across Canada, several provinces have broken daily case-count records in recent days and recommendations from federal health officials have slowly adjusted. Dr. Melissa Lem, a family physician in Vancouver, explained some of those new guidelines may change how Canadians should protect themselves against the disease. 

"Last week the Public Health Agency of Canada updated its website to include that possibility of aerosol transmission of COVID-19, or from tiny droplets that stay suspended in the air after someone coughs, sneezes or talks, as opposed to large droplets that fall to the ground quickly," she told CTV Morning Live earlier this week.

"This means we have to make sure we have good ventilation indoors to be clearing those small droplets away."

Lem said that could be why the PHAC updated its recommendation on masks to suggest face coverings should have three layers, including a filter. But Lem said the World Health Organization has been recommending three-layer masks since the summer. The B.C. Centre for Disease Control also recommends using three-layer masks, especially if they're homemade.  

"They may be related because adding that filter layer does protect us better against smaller aerosols especially as we move indoors in the winter time," she said about the federal updates.

Lem warned that, if COVID-19 can spread through smaller droplets, Canadians will need to make sure they're protecting themselves against the disease in several ways. 

"We have seen some situations in Canada where aerosols very likely contributed to the spread of COVID-19, like an 85-person outbreak at a spin studio in Hamilton, or when the virus was found in the ventilation system at a nursing home in Montreal where hundreds of people were infected," she said.

"This really underlines how important it is to layer on protection, including wearing a mask. Just distancing and hand hygiene might not be enough." 

Dr. Melissa Lem's comments were part of a six-minute interview. Watch the full interview on the video player above.