Environment Canada has issued a special air quality statement for the area.
The weather agency says hot and humid weather conditions are creating elevated levels of ground-level ozone.
"Individuals may experience symptoms such as increased coughing, throat irritation, headaches or shortness of breath," stated Environment Canada.
The air quality should improve with the temperature cooling off overnight and into Sunday (Aug. 21).
"Children, seniors, and those with cardiovascular or lung disease, such as asthma, are especially at risk."
The air quality statement is in effect for Edmonton, Sherwood Park, Fort Saskatchewan, Redwater, Bon Accord, Gibbons, Lamont, Bruderheim and Morinville.