Why the Sask. Roughriders postponed, but other sports played on: how air quality indexes work

CBC

4 days ago

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Saskatchewan Roughriders fans who headed to Regina's Mosaic stadium Friday had a rough night, sitting through rounds of delays and ultimately the postponement of the game more than three hours after the scheduled kick-off time.
While the Riders postponed, other sports in Saskatchewan played on, despite much of the province being blanketed in wildfire smoke last weekend.
Experts say there is no single rule for making decisions to postpone or cancel sporting events due to air quality, and specific leagues have different health guidelines.
"Different sports require different amounts of huffing and puffing and exposure time," said Madeline Orr, an assistant professor of sport ecology at the University of Toronto whose research focuses on how climate change impacts sports.
"Depending on the sport, depending on the exposure time, depending on how old the people are, these are all factors that should be considered. There is no one standard policy," Orr said.
She said the Canadian Football League has air pollution guidelines, but no rules.
Sports should be stopped as soon as the air becomes unsafe for people with sensitive conditions and wildfire smoke is particularly dangerous, Orr said.
With various air quality indexes available, and as wildfire smoke becomes an increasingly common health risk, here's what often goes into the decision to play or not — and how to make sense of air quality indexes when making your own decisions.
What is the 'Air Quality Health Index'
The Air Quality Health Index (AQHI) is run by Environment and Climate Change Canada (ECCC) and used widely across the country. It is meant to rate the health risk of three types of dangerous contaminants in the air on a one-to-10 scale — the higher the number, the greater the risk.
"It helps individuals make a judgment call around the air quality that they are breathing," said Céline Audette, manager of health and air quality forecast services at ECCC.
Any rating of five or higher means at-risk people and those with pre-existing conditions should consider heading inside, she said. At seven, the general population should take precautions. At 10, everyone is at risk and exposure could cause health effects, Audette said.
While other air quality indexes measure the concentration of specific pollutants in the air, the AQHI is based on epidemiologists' estimation of "the likely impact of that level of the pollution on the population," said Amir Hakami, an environmental engineering professor at Carleton University in Ottawa.
He works on air quality models similar to the one ECCC uses to create the AQHI.
The ECCC's national air pollution surveillance program uses more than 130 stations across Canada to measure air pollutants every hour. A model is then used to predict what the air quality and the corresponding health rating would be at areas not being tested.
Why different indexes can have different numbers
Experts say even a few metres can make a measurable difference in air quality safety, because of things like airflow and pollutant sources. For example, if you are standing immediately next to a car's exhaust, the air will be very different than if you were standing a few metres upwind.
There are also different formulas for measuring air quality. If you see a scale going higher than 10, it is likely a traditional air quality index measuring the specific level of pollutants.
The United States primarily uses a one-to-500 scale, applying a colour code to signify health risks. Canada calculates health risk differently, focusing on slightly different pollutant categories.
"The air quality indexes that are used in the States are usually based on regulations" and not necessarily "health impacts," Audette said. She said Canada's index uses "the best science available."
Wildfire smoke prompted ECCC changes in 2024
Wildfires create particles in the air that are so small they can only be seen with a microscope and are easily inhaled. The smoke falls into a pollutant category called PM2.5, or fine particulate matter that measures less than 2.5 micrometres.
"You can breathe it in, it can settle into your lungs and even cross the cellular level and go into your brain," Audette said. "This particle is toxic at any concentration."
She said wildfire smoke requires you to act quickly. Stations across Canada started measuring air quality every hour in 2024 because of the wildfires. Previously, the tests were done every three hours.
Softball tournament continued in Prince Albert
In Prince Albert, about 315 kilometres northwest of Mosaic stadium, the WBSC Men's Softball World Cup tournament continued Friday night and through the weekend.
Tournament co-chair Ian Litzenberger said the weather was great and it was a "perfect weekend for ball."
Litzenberger said that when wildfire smoke started rolling in, officials and the on-site medical director used air quality documentation from both Softball Canada and Softball Saskatchewan to make a call about continuing. He said they used multiple air quality indexes, including ECCC's.
None of our air quality levels ever surpassed what the documentation recommended, Litzenberger said.