Hazy skies return to Calgary as experts warn conditions will likely persist — and could get worse

Hazy skies returned to Calgary this week, with experts saying smoke from wildfires in northern Alberta, British Columbia and the United States is slowly entering the city, creating conditions that will linger and could get worse.

Sitting Tuesday morning at an Air Quality Health Index (AQHI) of 6, or moderate risk, experts say it is likely to remain the same throughout the week but the winds could shift.

"If anything changes, let's say if the winds start coming more towards Calgary, then we're going to see a little bit more significant impact," said Mandeep Dhaliwal, air quality program manager with the Calgary Region Airshed Zone. "Then the air quality can go into high risk to human health."

While wildfire season has been comparatively mild versus this time last year — just shy of 1.5 million hectares have burned across Canada compared to around 8 million that had burned by July 2023 — experts say hot, dry conditions persist and wildfires are starting to gain traction. 

"I'm actually a little surprised that the wildfires haven't impacted us significantly earlier than what we have seen so far," Dhaliwal said. "But this is not to say that it's not going to get any worse."

An update from Alberta Wildfire says there are four wildfires of note burning near the Cattail Lake Complex, Fort McMurray and Fort McKay.

Fires are also burning close to the Alberta-B.C. border in the Kootenay, Antler Creek and Shetland Creek regions.

Dhaliwal says projections from FireSmoke.ca show wildfire smoke from those regions blowing into Calgary over the next few days. 

When measuring air quality, Dhaliwal says they monitor three pollutants — nitrogen dioxide, ground-level ozone and particulate matter (PM) 2.5. The latter is more easily trapped in our airways and comes from wildfire smoke and other pollutants like car exhaust. 

"When it comes to wildfires, the pollutant that's in the wildfire smoke is PM2.5, which can travel thousands of kilometres away," Dhaliwal said, adding it can be hard to predict where smoke will go.

As of Tuesday at noon, PM2.5 levels were around 47 micrograms per cubic metre of air in Calgary. The World Health Organization recommends PM2.5 levels should not exceed 5 micrograms.   

Smoke not the only factor

But wildfire smoke doesn't act alone, Dhaliwal says, explaining how less wind and warmer temperatures can increase ozone levels and worsen air quality. 

"Any time you have higher temperatures, higher sunlight, you'll have higher amounts of ground-level ozone, which is going to make it difficult to breathe out there as well," Dhaliwal said.  

Wildfires and heat also mean pollutants hang in the air longer, says Brian Proctor, a meteorologist with Environment and Climate Change Canada.

Proctor says current weather patterns have created a ridge of high pressure in the atmosphere over B.C., Alberta and western Saskatchewan. The ridge, he said, creates a "subsidence air mass aloft" where dense air — in this case, smoky air — sinks lower in the atmosphere.

"We're seeing more of that smoke that's been injected into the atmosphere really settling out or subsiding in the atmosphere down closer to the surface," Proctor said. "So we're getting more smoke subsiding over top of us."

Proctor says current projections show the ridge could collapse by the end of the week in northern Alberta and B.C., bringing cooler temperatures but not necessarily an end to smoky conditions. 

"What that may do to us moving forward is we might see a little bit of reduction in temperatures towards the end of the work week, but we may see more smoke drifting into southern Alberta from British Columbia," he said. 

Proctor says the worst wildfire conditions in B.C.'s southern interior often arrive in August, and with more fires beginning to burn conditions are likely to change.

"We've got a long way to go in this wildfire season and a lot of time to spend still before we can really declare us out of that portion of the year," he said.

Breathing easier

Under moderate AQHI conditions, Environment Canada advises people to consider reducing strenuous activity if they belong to an at-risk group or are experiencing symptoms such as coughing or a sore throat.

Dhaliwal says seniors and young children can suffer the most when the air quality is poor, and recommends they stay indoors whenever the AQHI is higher than 3.

"They're taking more of this pollution in. So it gets very, very hard for them," Dhaliwal said. "Once you reduce [exposure], then you have a higher chance of facing this air pollution."

Proctor adds that while staying indoors can help, for vulnerable populations — like the homeless or lower-income communities — it can exacerbate the issue, primarily for those who do not have access to air conditioning or other methods of indoor cooling.

"Oftentimes, when we see these really significant heat events, what we're doing is putting that at-risk population into even greater threat sometimes by not getting them out of those very warm situations inside their homes or shelters," he said.

"It's very important that we consider other people other than ourselves in these kinds of situations."