TORONTO -- Environment Canada is warning of “deteriorating air quality” in Toronto as hot and humid weather continues in the city.

Toronto has been in the grips of an extended heat wave for more than a week now and the situation has prompted the national weather agency to issue its first special air quality statement of the season for Toronto and other parts of the GTA, including parts of Durham, York, Halton and Peel regions.

“Hot and sunny conditions are expected to cause increasing ground-level ozone concentrations in the area,” the weather advisory read.

“Individuals may experience symptoms such as increased coughing, throat irritation, headaches or shortness of breath. Children, seniors, and those with cardiovascular or lung disease, such as asthma, are especially at risk.”

Toronto, which remains under a heat warning, is expected to see a high of 35 C today but the temperature will feel closer to 42 with the humidity.

The sweltering heat is expected to continue on Friday with the humidex value surpassing 40 once again.

The City of Toronto confirmed Thursday that hours at six outdoor pools will again be extended to 11:45 p.m. tonight to offer residents respite from the heat.

People are urged to reschedule strenuous outdoor activities until the air quality statement is lifted.

Torontonians are in for a bit of a break over the weekend, when daytime highs dip below 30 C on both Saturday and Sunday.