The Minnesota Pollution Control Agency has upgraded an air pollution health advisory issued Wednesday for Rochester and the Twin Cities to an air pollution alert through Friday.
The MPCA issues an air pollution advisory when the amount of fine pollution particles in the air approaches a level that is considered unhealthy for certain groups.
Those groups include people with respiratory or cardiovascular problems, young children, the elderly, and people who participate in activities that require heavy exertion.
The MPCA cautions that even individuals who are otherwise healthy may experience health problems when air pollution increases.
Officials have urged residents to reduce or postpone activities that lead to deep or accelerated breathing, as fine pollution particles can be inhaled deeply into the lungs.
Exposure to high levels of fine particles may cause chest pain, shortness of breath, coughing and fatigue, even after air quality has improved.
Officials have urged residents to help reduce air pollution by carpooling, using public transportation, and avoiding car idling.
During poor air-quality times, the MPCA also recommends that people postpone burning wood and reduce their energy consumption.
The alert will be downgraded to an advisory on Saturday. MPCA officials say that air quality should return to normal levels by Monday.