Light winds paired with a change in temperature have trapped smog over Calgary, prompting a special weather statement alert from Environment Canada.
On Thursday at 5: 30 p.m., the agency warned that high levels of air pollution will remain over the city until westerly winds blow in later in the evening, dispersing the smog.
Environment Canada warned that people could experience symptoms including coughing, throat irritation, headaches and shortness of breath. Children, seniors and people with cardiovascular or lung problems are especially at risk.
The government's Air Quality Health Index rated Calgary's air as a high risk.
The risk is projected to drop to low by noon Friday.
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