Air Quality Index (AQI)

The Air Quality Index (AQI) is a color-coded system, with each color representing a different level of health concern. This is important as we enter the wildfire season. Here are the AQI colors and their levels of concern:

Green (0-50): Good.

Air quality is satisfactory, and air pollution poses little or no risk.

Yellow (51-100): Moderate.

Air quality is acceptable, but there may be a risk for some people, particularly those unusually sensitive to air pollution.

Orange (101-150): Unhealthy for Sensitive Groups.

Unhealthy for Sensitive Groups (children, older adults, people with respiratory or heart conditions) who may experience health effects.

Red (151-200): Unhealthy.

Some of the general public may experience health effects; members of sensitive groups may experience more serious health effects.

Purple (201-300): Very Unhealthy.

The general public may experience health effects.

Maroon (301 and above): Hazardous.

Health effects are likely to occur in all individuals.

Wildfire Health Risks

Source: MN Department of Health, New York Times & Canadian Source

“In Minnesota, a typical year brings an average of 1,200 wildfires that burn through 12,600 acres, according to state data. Since the beginning of this year, more than 1,000 wildfires have already destroyed more than 50,000 acres,” states the May 17, 2025, NY Times article. According to the Canadian Wildland Fire Information System, the fire severity level is above average, however rain levels are predicated to increase during this summer.

Wildfire smoke is a mix of gases and fine particulate matter from burning vegetation and materials. The pollutant of most concern from wildfire smoke is fine particulate matter (PM 2.5). PM 2.5 from wildfire smoke is damaging to human health because it has the ability to deeply penetrate lung tissue and even affect the heart and circulatory system.

Wildfire smoke can make anyone sick. Breathing wildfire smoke can have immediate health impacts, including respiratory and cardiovascular effects. Particle pollution may also affect the body’s ability to remove inhaled foreign materials, such as viruses and bacteria, from the lungs.

Who's most at-risk?

Some populations may experience more severe acute and chronic symptoms from exposure to wildfire smoke including:

• Children: Their lungs are still developing and there is a greater likelihood of increased exposure to wildfire smoke because of more time spent outdoors, engaging in more vigorous activity and inhaling more air per pound of body weight compared to adults.

• Older adults: Adults older than 60 can be at a higher risk of harmful effects from wildfire smoke due to the frequency of pre-existing respiratory and heart conditions, as well as a decline in natural physiological defense systems.

• People with chronic respiratory or cardiovascular disease: Individuals living with heart or lung diseases, such as coronary artery disease, asthma or chronic obstructive pulmonary disease (COPD), are more likely to be affected when fine particle pollution reaches an unhealthy level.

Air Quality Index

Meteorologists at the Minnesota Pollution Control Agency (MPCA) forecast the Air Quality Index (AQI) at 18 locations in five regions across the state. Forecasts are important to help Minnesotans who are sensitive to air pollution for planning ahead to protect their health.

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 above categories (unhealthy for everyone). 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.