Feeling hazy from the wildfire smoke? Here's why

Calgary Herald

11-06-2025

With seasonal wildfire smoke rolling into Calgary, residents often have questions about all the things that come with it.
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On June 11, Environment Canada issued an air quality warning for Calgary between the AQHI categories of 7 and 10 over the last 24 hours.
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But what does that mean? How are these measured? And how does it affect the health and safety of Calgarians? Experts from across the province explain how air quality is measured and the risks that come with it.
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Christy Climenhaga, a scientist with Environment and Climate Change Canada, said Canada's Air Quality Health Index serves as a way to help evaluate the adverse effects of wildfire smoke.
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The index itself ranges from one to 10-plus, with different brackets indicating each risk factor. For example, indexes between one to three indicate a low risk, four to six indicate a moderate risk, and seven to 10 indicate a high risk.
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'So, the higher the number, the higher the risk,' Climenhaga said. 'When you're looking at seven, eight, nine, you are in that high-risk category, while 10 and 10-plus are very high risk in terms of negative health effects from wildfire smoke.'
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The rating is determined by looking at the fine particulate matter. This matter is also known as PM2.5, which is extremely small particles in the air. It measures around 2.5 micrometers, and cannot be seen by the human eye.
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Based on their observations, Climenhaga said a number of fires over northern Alberta and B.C. have lofted heavy plumes of smoke into the atmosphere. Additionally, a large and intense plume of smoke that stretches across all of Alberta and Saskatchewan are contributing to the smoke arriving in Calgary.
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'It's likely going to keep going to be a smoky day today, and we are starting to see some changes in our long-range forecasts, indicating a little smoke on Thursday, then starting to clear out on Friday,' she said.