Here's where wildfire smoke is spreading in Canada and the U.S.

Shaki Sutharsan · CBC News

· Posted: Jun 02, 2025 11:08 PM EDT | Last Updated: 8 hours ago

As wildfires proceed to rage successful Western Canada, communities successful affected areas and surrounding provinces person been blanketed by heavy plumes of smoke, prompting aerial prime alerts extending into parts of the United States this week.

Smoke conditions successful immoderate parts of the U.S. Midwest person become so atrocious that the aerial prime has been categorized arsenic "hazardous."

Exposure to wildfire fume has been recovered to origin aboriginal decease and respiratory issues, says a 2024 study from Health Canada.

Which provinces person been affected truthful far?

Air prime warnings person been issued by Environment and Climate Change Canada throughout Manitoba, Saskatchewan, Alberta and Ontario. Fifty-three communities successful southeastern Manitoba, for example, person received alerts astir wildfire fume causing mediocre aerial prime and reduced visibility.

The warnings stated that conditions successful immoderate Manitoba regions are improving arsenic the fume drifts eastward and distant from the affected communities, but it is expected to linger successful areas similar Flin Flon and Cross Lake, wherever section wildfires are inactive evading control.

Communities successful bluish Saskatchewan, specified as La Ronge, person besides been nether aerial prime warnings for the past respective days. La Ronge, Air Ronge, the Lac La Ronge reserve and different communities wrong a 20-kilometre radius have present been ordered to evacuate. 

A fig of peculiar aerial prime statements were besides issued for much than a twelve communities successful northwestern Ontario aboriginal Monday morning. The statements warned that wildfire fume was expected to stay successful the country for the adjacent respective days.  

What parts of the U.S. volition beryllium impacted? 

Over the weekend, fume drifted toward the Upper Midwest successful the U.S., impacting northwestern Wisconsin, eastbound Nebraska, northeastern North Dakota and astir of Minnesota.

A statewide aerial prime alert has been issued for Minnesota until Wednesday by the Minnesota Pollution Control Agency. The alert states that the fume volition apt scope northwest and north-central Minnesota by Monday evening, pursuing down a acold beforehand that's moving southeast.

The Air Quality Index values utilized successful the U.S. are expected to scope the "hazardous" class successful northwestern Minnesota. At that level, the nationalist is advised to debar carnal enactment outdoors, and high-risk groups — including those with lung and bosom disease, seniors and young children — should stay indoors.

The alert warns residents successful northwestern Minnesota that they tin besides expect mild ashfall and reduced visibility. 

Where is the fume headed?

The fume is expected to drift southeast successful the coming days, according to BlueSky Canada's fume forecast, which combines Alberta and British Columbia's wood occurrence information with upwind forecast models to foretell fume concentrations. 

How atrocious is the aerial quality? 

Air Quality Health Index (AQHI) values — the standard utilized successful Canada to subordinate aerial prime to wellness — were astatine 7 successful Flin Flon connected Monday evening, putting it successful the "moderate" wellness hazard category.

An aerial prime informing for Flin Flon issued connected Monday greeting stated: "During dense fume conditions, everyone's wellness is astatine hazard careless of their property oregon wellness status."

The standard comprises 4 categories, ranging from "low" wellness hazard to "very high." The AQHI values are grouped into these categories, with immoderate worth from 1 to 3 deemed a debased wellness hazard to the wide nationalist and a worth of 10 oregon much posing a precise precocious risk.

In Winnipeg, the AQHI was astatine four, posing a "moderate" wellness risk. In Saskatchewan, astir regions were observed to person AQHI values astatine "low risk" connected Monday evening.

Fort McMurray and Grande Prairie successful Alberta were astatine 7 and eight, respectively, putting them successful the "high risk" category.

Air prime tin alteration from hr to hour, and fume conditions tin alteration implicit abbreviated distances, an aerial prime connection for Grand Rapids and Easterville successful Manitoba stated. 

Who volition beryllium astir affected? 

According to Environment and Climate Change Canada, the radical who are astatine the highest hazard of facing wellness impacts owed to debased aerial prime caused by wildfire fume include: 

• Seniors.
• Young children.
• Pregnant women.
• People who enactment outdoors.
• People progressive successful strenuous outdoor activities.
• People with chronic wellness conditions, specified as:
  • Cancer.
  • Diabetes.
  • Lung oregon bosom conditions, including asthma.
  • Mental illness.

When AQHI values are astatine "moderate" to "very precocious risk" levels, those who are astatine higher hazard are advised to trim oregon wholly debar strenuous outdoor activities entirely. 

What are semipermanent effects of wildfire smoke exposure?

In a information expanse astir the wellness effects of wildfire smoke, the B.C. Centre for Disease Control stated that smoky aerial tin summation the hazard of some infections, specified arsenic pneumonia and COVID-19, arsenic good as ear infections successful children.

The centre lists portable aerial cleaners with HEPA filters arsenic a mode to region fume particles from indoor air. It besides recommends keeping car windows closed erstwhile driving and aerial conditioners turned connected to bounds letting successful extracurricular aerial arsenic overmuch arsenic possible.

According to a 2024 study by Health Canada's Water and Air Quality Bureau, determination was "strong and accordant evidence" that wildfire fume vulnerability tin origin "premature mortality" and respiratory issues.

The study besides concluded that vulnerability to wildfire fume tin worsen pre-existing asthma and chronic obstructive pulmonary disease.