As wildfires maintain a fierce grip on western and northern regions of Canada, the smoke is projected to spread across the Prairie provinces into the weekend, and potentially further east across the country.

This is Canada’s worst-ever wildfire season with more than 1,000 active fires burning across the country, including 265 in the Northwest Territories.

A state of emergency was declared in Kelowna, B.C. on Thursday and residents of Yellowknife, the capital of the Northwest Territories, have until 12 p.m. MT on Friday to evacuate as smoke continues to billow in the area.

“Smoke from wildfires is still expected to affect a large part of the Prairie provinces into the weekend,” explained Global News meteorologist Ross Hull. “Winds out of the northwest have been driving smoke from wildfires in B.C., northern Alberta and the Northwest Territories to the south and east across the country.”

Parts of northern Ontario and Quebec could have air quality impacts due to this smoke, he said. And a change in wind direction will likely alleviate the current smoke risk in central and eastern Canada into the weekend.

BlueSky Canada, a forecast system showing weather and forest fire information, projects the wildfire smoke from western Canada will make its way across the country into Friday evening and even stretch as far as New York City.

Environment Canada has also issued special air quality statements for parts of central and eastern Canada.

In southern Saskatchewan, wildfire smoke from fires in southern B.C. is moving across the province Friday, according to Environment Canada.

“Conditions will improve this evening when a cold front sweeps across the area,” the environmental department said. “Wildfire smoke concentrations can fluctuate over short distances and vary considerably from hour to hour.”

In parts of northern Manitoba, smoke from the wildfires is expected to cause poor air quality and reduced visibility, but “improvement is expected later today as the current smoke plume is pushed off east,” Environment Canada said.

And in northern Ontario, Environment Canada said, poor air quality conditions due to smoke from forest fires have developed and the conditions are likely to persist Friday evening across far northwestern Ontario before improving.

Federal Health Minister Mark Holland, spoke about the wildfires Friday at the Canadian Medical Association summit in Ottawa, highlighting the link between poor air quality and health.

“The evacuation that is occurring, the devastation that is happening there…that some folks are going to come back and now have a home…how could you not be gripped by that?” he said.

“The declining planet with worse air and extreme weather events is going to have incredibly injurious effects on our health-care system. In the Northwest Territories today what are we doing with the folks who have to evacuate and can’t go to health-care providers in their own jurisdiction?”

When a wildfire burns, it releases pollutants into the air, including sulphur dioxide, carbon monoxide, nitrogen oxides and volatile organic compounds, which can be hazardous to human health in the short and long term.

“It can travel miles and miles away from the actual fire,” Angela Yao, a senior scientist at B.C. Centre for Disease Contro, previously told Global News on May 11.“And when it reaches us, it can get pretty deep into our lungs and cause inflammation.”

And symptoms from wildfire smoke can vary.

Mild symptoms may include irritated eyes, sore throat or headaches. More severe symptoms such as wheezing, shortness of breath and chest pains are more likely to affect vulnerable groups such as young children, the elderly, pregnant women and those with preexisting conditions like asthma or diabetes, Yao said.

The first way to protect yourself against wildfire smoke is to check the Health Canada Air Quality Health Index, Dr. Courtney Howard, an emergency physician in the Northwest Territories who is also a wildfire and health researcher, previously told Global News.

The air quality health index ranges from low risk (around one to three on the scale) to high risk (around seven to ten on the scale).

If the air quality index is reading high risk, Howard said, people should refrain from any outdoor activity and stay inside if possible.

If the scale is moderate risk, Howard said people who have varying vulnerabilities, such as a preexisting respiratory condition, may want to modify their activities as there is some risk.

Another way to stay protected is to invest in a high-efficiency particulate air (HEPA) filter, she added.

“If you do need to go outside, it is recommended to put on an N95 or KN95 mask,” Howard said. “If you do have a well-fitting mask, it can filter out a majority of the smoke.”

— With files from Reuters