Alberta Health Services has issued a precautionary air quality advisory for Edmonton as well as areas east of the city.
According to Alberta Environment, the Air Quality Health Index was 7 on a scale from one to 10 at 11 a.m. Thursday.
The maximum forecast for the day is 8. A rating from 7 to 10 is considered high risk.
A weather event known as an air inversion is trapping pollutants close to the ground, said Dr. Chris Sikora from Alberta Health Services.
"Around the Edmonton area they do happen infrequently," he said. "It does tend to happen in the winter months."
The current situation isn’t expected to cause problems for most healthy people but may aggravate symptoms for those with respiratory and cardiovascular conditions.