Smoke is causing poor air quality and reducing visibility.
It is expected to be ongoing.
The high level of air pollution is due to smoke from ongoing forest fires in northwestern Ontario moving over Southwestern Ontario.
Elevated particulate matter levels and hazy conditions have been reported across several measuring stations.
The reduced visibility and deteriorating air quality occurs if the smoke descends to ground level.
Conditions are expected to improve Tuesday with the passage of a cold front.
Visit airhealth.ca for more information.