A special air quality statement is in place because of the possibility of deteriorating air quality.
Environment Canada issued the alert for much of Southwestern Ontario, including Chatham-Kent and Windsor-Essex, at 9:30 a.m. on Tuesday.
"Weather conditions are expected to cause increasing levels of ozone," a statement from the weather agency said, adding that the combination of ozone and residual wildfire smoke could briefly cause high-risk Air Quality Health Index (AQHI) values.
The air pollution could cause mild and common symptoms such as eye, nose, and throat irritation, headaches, or a mild cough. More serious but less common symptoms include wheezing, chest pains, or a severe cough.
People most likely to be affected by poor air quality are the very old, the very young, pregnant people, individuals who work outdoors, and those with existing health issues.
Environment Canada advises that people reduce time outdoors, if possible, while the statement is in place.