Air Quality Index Basics
Refer to the chart above when determining whether air quality is a concern for you and your family.
By Charlie Lippert DNR Air Quality Specialist
Mille Lacs Band communities have fallen under an unprecedented number of air quality alerts this summer, due to smoke from wildfires across the U.S. and in Canada — and it looks like the conditions may persist into the fall. The U.S. Air Quality Index (AQI) developed by the U.S. Environmental Protection Agency (USEPA) is a quick reference index for reporting ambient air quality. The EPA has established AQI values for five major air pollutants regulated by the Clean Air Act.
Each of these pollutants has a national air quality standard set by USEPA to protect public health: ground-level ozone, particle pollution (also known as particulate matter, including PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
The air pollutant with the highest value is then reported as the area’s AQI. What do the values mean? Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.
For each pollutant, an AQI value of 100 generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for protection of public health. AQI values at or below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is unhealthy — at first for certain sensitive groups of people, then for everyone as AQI values get higher.
For quick reference, AQI is divided into six categories. Each category corresponds to a different level of health concern.
Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities.
Community AQI can be looked up at USEPA’s AirNow web- site at https://www.airnow.gov/. Additionally, during wildfire season to see what the regional air quality monitors and sensors are reporting, a joint USEPA and US Forestry Service effort to track and report wildfire smoke movement and on the ground air quality conditions can be viewed through AirNow Fire and Smoke website at https://fire.airnow.gov/.
There also are commercial sites that report estimated AQI values to help inform the public. These sites include PurpleAir (https://www.purpleair.com/), IQAir (https://www.iqair.com/ air-quality-map), and the Weather Underground’s WunderMap (https://www.wunderground.com/wundermap).
For the Mille Lacs region, the Minnesota Pollution Control Agency operates a particulate matter monitor at the Brainerd Regional Airport, and the Mille Lacs Band of Ojibwe DNR operates an ozone monitor at the Iskigamizigan Powwow Grounds. The area is also served by five PurpleAir particulate matter sensors located at Ideal Corners by Pequot Lakes, at Vineland, Minisinaakwaang Leadership Academy in East Lake, at Pokegama west of Pine City, and at Johnson Lake south of Danbury, Wisconsin. The Minnesota Pollution Control Agency is actively encouraging Minnesotans especially in northern and western Minnesota to participate in citizenry science by purchasing and hosting a PurpleAir particulate matter sensor, as the sensor can be used for air quality trend analysis and serve as an early warning system for wildfire smoke that typically blows in from the western U.S. and from Canada.
