Smog alert issued for southern Ontario

Much of southern Ontario, including Toronto, has been issued a smog alert.

Environment Canada predicts Saturday’s air quality index will exceed 50, which is the threshold for a poor rating.

The partly sunny and hot conditions across the region will combine with pollutants to generate smog, the agency said.

Environment Canada recommends avoiding unnecessary vehicle trips and limiting the use of gas-powered machines such as lawn mowers.

Strenuous outdoor activities could cause coughing or shortness of breath, the agency warns.

Saturday’s daytime high is listed as 29 C, and the UV index is 10, or very high. The forecast called for a 30 per cent chance of showers and the risk of a thunderstorm late in the afternoon.

There’s a chance for more rain this evening, but the weather should clear overnight, with a low of 21 C.

Both pollution levels and the humidex are expected to improve Sunday after a weak cold front rolls in.

Environment Canada predicts Sunday in Toronto will be sunny, with a north wind blowing in late in the afternoon. The daytime high is 29 C.