The summer blue skies in the National Capital Region have been replaced by a gray, smoky haze over the past two days as wildfires blazed in northwestern Ontario and east-central Manitoba.
Environment Canada spoke to meteorologist Gerald Cheng to find out how wildfires can have such a dramatic effect on the air we breathe.
Cheng said the simple explanation is that smoke from more than 200 wildfires in northwestern Ontario and Manitoba spread across the province by Tuesday and set up shop here.
The smoke from those fires – composed of a complex mixture of gases, particulates and water vapor – is reducing outdoor visibility and deteriorating air quality. It is also causing the Sun to appear as a giant red ball at times.
The increasing presence of particulate matter and foggy conditions in the air prompted Environment Canada to issue an air quality statement for parts of eastern Ontario and a smog warning for western Quebec.
“We are concerned about the concentration level of a pollutant called PM 2.5,” Cheng said. “It’s a pollutant that results from wildfires. And its source is actually the fires in northwestern Ontario and Manitoba.”
According to the BC Center for Disease Control, PM 2.5 is microscopic soot particles that can travel deep into the lungs, where they can cause inflammation, irritation and difficulty breathing.
How did all this smoke get here?
Blame the airflow.
“It’s really about how the winds are carrying the smoke to the rest of the province and other areas,” Cheng said. “And it’s about air circulation and how the air is traveling in the atmosphere.”
Everywhere from Windsor to Ottawa and even Quebec – everyone is affected.
Cheng said the wind traveled west to east over the weekend, taking smoke from fires in Manitoba and northwestern Ontario and pushing it east until it “invaded” northeastern Ontario.
Winds from the north pushed the smoke south until it covered much of southern and eastern Ontario.
“That’s why we’re seeing this smoke in this area,” Cheng said. “Everywhere from Windsor to Ottawa and even Quebec – everyone is affected.”
When will the haze dissipate?
Short answer: within the next 24 hours.
Cheng said a cold front made of clean air is moving south from the Hudson Bay toward the region. It was expected to reach by Tuesday afternoon and will gradually reduce the level of PM 2.5 in the air and the smoky air will move south and east.
“We are waiting for him to pass through the Ottawa Valley and clear the air,” Cheng said.
Cheng said that air can sometimes get trapped in the valley, which makes it take longer to spread than on flat land.
“It takes longer than other areas that are at higher altitudes to clean, expel the air,” Cheng said.
How is smoke affecting air quality?
According to the Canadian government, Ottawa’s air quality was at a level of 5 on a scale of 10 on Tuesday, indicating a moderate risk (10 or more signifies highest risk, while 1 is considered low risk), according to the Canadian government.
“When air quality is bad, it really affects the most vulnerable, people who already have respiratory diseases. [like] Asthma, for example,” Cheng said. “It makes breathing difficult.”
Cheng said healthy individuals would not be affected as much.
“As concentration levels drop, air quality will improve,” Cheng said. “But to see a clear difference, we’ll have to wait until Wednesday when we can breathe easier.”