Environment Canada has issued a special air quality statement for London, Parkhill, Strathroy, Komoka and Middlesex County.
This statement is the second one this weekend, with Environment Canada having issued a statement Friday.
According to the weather agency, southwestern Ontario could possibly have high levels of air pollution today.
In addition, the hot and sunny conditions are expected to cause increasing ground-level ozone concentrations in the area.
Environment Canada says moderate risk air quality health index (AQHI) values are expected throughout today with the potential for higher risk AQHI values this afternoon in southwestern Ontario. They add the potential exists for the statement to continue Monday, as southwestern Ontario could register extreme AQHI values.
The weather agency says you might 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.
Environment Canada advises anyone experiencing these symptoms to remain indoors.