The Minnesota Pollution Control Agency has issued an air quality alert for the southern half of Minnesota, which started Friday evening and continues through midday Sunday.

Canadian wildfire smoke coming from British Columbia, Alberta, and western Ontario was expected to move south starting Friday, according to a press release. Waves of smoke will move over the state with air quality beginning to be impacted in the St. Cloud to Twin Cities area by Saturday morning and Mankato and Rochester by the afternoon hours.

Periods of smoke are expected to persist through Sunday morning, the release states.

During this time, fine particle pollution is expected to remain at or above a level that is considered unhealthy for sensitive groups. By Sunday afternoon, winds will switch to the south, improving air quality conditions.

People who are more likely to be affected are the following:

• People with asthma or other breathing conditions

• People with heart disease or high blood pressure

• Children and older adults

• People of all ages doing extended or heavy physical activity

The release states air pollution can aggravate heart and cardiovascular disease, as well as lung diseases. When the air quality is unhealthy, people with these conditions may experience symptoms like chest pain, shortness of breath, wheezing, coughing or fatigue.

People are advised to take precautions, including limiting or postponing physical activity and staying away from local sources of air pollution.