Environment Canada is warning of possible “deteriorating air quality” in parts of southern Ontario on Friday.
Included in the advisory are the Greater Toronto Area, Hamilton, the Niagara Region, and London.
“Hot and sunny conditions are expected to cause increasing ground-level ozone concentrations this afternoon,” the statement said.
Moderate air quality health index values are possible through the afternoon, with short-term high risk levels that could last a couple hours.
“Exposure to air pollution is particularly a health concern for people with heart or breathing problems, those with diabetes, children and the elderly,” Environment Canada said.
Increased coughing, throat irritation, headaches or shortness of breath is possible.
Southern Ontario has seen unusually warm summer-like weather this week. Environment Canada is forecasting a high of 26 C and sunshine for Toronto on Friday, with a humidex of 27.
The average high for April 14 is 11.1 C.
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