Air Quality Index: facts & figures

In Minnesota, the Air Quality Index (AQI) is based on measurements of four pollutants: fine particles (PM2.5), course particles (PM10), ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide. Each hour, the Minnesota Pollution Control Agency (MPCA) converts measurements to an AQI value based on health standards established by the US Environmental Protection Agency.

In 2016, the MPCA reported the AQI in 11 regions across the state: Brainerd, Detroit Lakes, Duluth, Ely, Grand Portage, Marshall, Rochester, St Cloud, the Twin Cities, and Virginia. See current air quality conditions in Minnesota

Since air quality affects health, the AQI can help people prevent the health effects of exposures to air pollution. On days with "moderate" air quality (yellow), air pollution levels are elevated and may cause health effects for people who are vulnerable to air pollution.

The MPCA issues an air quality alert on days when the AQI is above 100 ("unhealthy for sensitive groups"). On these days, air pollution levels may cause adverse health effects for people with cardiovascular disease, lung disease, older adults, children, and even healthy people doing vigorous activity. 


Air Quality Index, by region

 
 
Color AQI Category AQI
  Good 0-50
  Moderate 51-100
  Unhealthy for sensitive groups 101-150
  Unhealthy 151-200

Source: Minnesota Pollution Control Agency 2016. Data not available for all days at each monitor, because monitors may go down or record invalid data.

 

In 2016, across all areas of the state, more than 75 percent of days were rated "good" for air quality. Grand Portage experienced the highest number of good air quality days (354). The Twin Cities had the lowest number of good days (295). Statewide, air quality reached alert levels on 5 days. The Twin Cities experienced the most bad air days (3). In 2016, Duluth, Marshall, and Rochester each experienced one bad air day.

Because most air quality alerts in Minnesota are driven by weather, year to year changes in the weather can impact the number of air quality alerts each year.


Air alert days, by region

 
 
Source: Minnesota Pollution Control Agency 2005-2016. The health standards used to calculate the AQI and air alert days have changed over time. AQI results from past years have been adjusted to reflect what would have been air alert days using the current air quality standards.

 

In Minnesota, the number of “bad air” days each year has generally been declining over time. On most days, air quality across Minnesota is healthy to breathe, but on some days each year the air can reach unhealthy levels. The amount of pollution in the air varies by how much pollution is emitted within an area, how much pollution is blown in from other areas, and the weather. Because most air quality alerts in Minnesota are driven by weather, year to year changes in the weather can impact the number of air quality alerts each year.

More information about the AQI

For additional ways to keep track of air quality:

Related topics: