The Air Quality Index (AQI) was developed by the U.S. Environmental Protection Agency (EPA) to provide a simple, uniform way to report daily air quality conditions.

Air quality in the Twin Cities metropolitan area is determined by measuring four pollutants: ground-level ozone (smog), sulfur dioxide, fine particulate matter (soot) and carbon monoxide. The Minnesota Pollution Control Agency takes hourly measurements of these pollutants at air quality monitoring sites located throughout the Twin Cities. Ozone levels, which are only elevated in warm weather, are measured from April through September in Minnesota.

The AQI translates each pollutant measurement to a common index; an index of 100 reflects where health effects might be expected in sensitive populations. The pollutant with the highest index value is used to determine the overall AQI. Click here to see today’s air quality readings >