“Air quality and visibility due to wildfire smoke can fluctuate over short distances and can vary considerably from hour to hour,” Environment and Climate Change Canada (ECCC) said in its statement.

A stretch of southern Ontario remains under a special air quality statement today amid smoke from wildfires burning in parts of the country. Environment Canada says smoke from forest fires can cause reduced air quality and visibility that can fluctuate throughout the day.

Environment Canada has issued special air quality statements for southwestern Ontario as Prairie wildfire smoke sits over swaths of the province.