Air Quality Index forecasting

Four men in an office looking at a tablet screen.

Meteorologists at the MPCA forecast the Air Quality Index (AQI) at eighteen locations in five regions across the state.  Forecasts are important to help Minnesotans who are sensitive to air pollution to plan ahead to protect their health.

Forecasting locations were chosen based on the availability of air quality monitoring data. While many pollutants are part of the AQI, air quality forecasting focuses on ozone and fine particles (PM2.5) since these are the pollutants that drive the majority of regional episodes of poor air quality. The role of forecasters is to predict the daily maximum 8-hour average ozone concentrations (March-October), and the 24-hour average of PM2.5 concentrations (year-round).  AQI forecasts are highly dependent on the weather forecast as weather can both enhance and decrease the formation of air pollution. To forecast ozone, meteorologists focus on predicting temperatures, relative humidity, pollution flowing in from other parts of the country (background), and cloud cover. To forecast PM2.5, some important weather considerations are relative humidity, visibility, background, and wind speed.

On most days, the AQI across Minnesota is in the green (good) category, but occasionally, the AQI climbs into the yellow (moderate) category, or even into the orange (unhealthy for sensitive groups) or red (unhealthy) categories. While sensitive populations such as those with asthma, chronic obstructive pulmonary disease (COPD), children, and older adults are more likely to experience health effects during orange and red AQI levels, unusually sensitive individuals can experience effects in the yellow category.  This is why accurate forecasts at all AQI levels are helpful for enhancing human health.

If the AQI forecast shows the potential of Index levels climbing over 100 (orange), the MPCA will issue an air quality alert through the National Weather Service, the Minnesota Air mobile app, EnviroFlash, email lists, and social media. Alerts identify those who may be impacted by poor air quality, as well as precautions to take to reduce exposure, and tips on how to reduce contributions to air pollution.

MPCA's current air quality page shows current AQI forecasts and alerts, and has links to download the Minnesota Air mobile app, sign up for EnviroFlash emails, and follow @mpca_aqi on Twitter.