These Cities Are Under Code Purple, Maroon for Bad Air Quality

Air quality continues to worsen across the Northeast and Midwest as more than 800 Canadian wildfires rage on.

As of Friday, July 17, air quality alerts remained in effect in multiple states, including parts of Minnesota, Wisconsin, Michigan, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, New York, Vermont, New Jersey, Delaware, Maryland, Virginia and the Carolinas, according to the National Weather Service. Some of the worst conditions have been concentrated around Detroit, Minneapolis, Chicago and New York in recent days.

To track air quality across the country, the U.S. Environmental Protection Agency (EPA) manages the Air Quality Index (AQI), a scale that ranges from 0 to 500 and measures how clean or polluted outdoor air is. Scores between 201 and 300 are coded purple and scores over 301 are coded maroon, both of which indicate a health risk to everyone, not just sensitive groups.

Here’s a closer look at what major cities are under codes purple and maroon for poor air quality on July 17.

What Cities Are Under Code Purple for Bad Air Quality?

According to AirNow, a government site that monitors the Air Quality Index, here are some major cities under code purple, as of July 17:

• Baltimore
• Cleveland
• Flint, Michigan
• Madison, Wisconsin
• Pittsburgh
• Philadelphia

What Cities Are Under Code Maroon for Bad Air Quality?

According to AirNow, here are some major cities under maroon, as of July 17:

• Detroit
• Duluth, Minnesota
• Chicago
• Columbus, Ohio
• Grand Rapids, Michigan
• Green Bay, Wisconsin

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What Is the Air Quality Index and How to Check It

The Air Quality Index (AQI) is a scale from 0 to 500 used to measure how clean or polluted the outdoor air is. The AQI for your area can be checked on the AirNow website by entering your zip code, city or state.

Here’s a closer look at AQI values:

• 0 to 50 (Green): Air quality is good and poses little to no risk for air pollution.
• 51 to 100 (Yellow): Air quality is acceptable but there is a risk for some people, especially those who are unusually sensitive to air pollution.
• 101 to 150 (Orange): Members of sensitive groups may experience health effects, but the general public is less likely to be affected.
• 151 to 200 (Red): Some members of the general public may experience health effects, and members of sensitive groups may experience serious health effects.
• 201 to 300 (Purple): The risk of health effects is increased for everyone.
• 301 or higher (Maroon): Health warning of emergency conditions, as everyone is more likely to be affected.

Contributing: Thao Nguyen, USA TODAY

Greta Cross is a national trending reporter at USA TODAY. Story idea? Email her at [email protected].

Reporting by Greta Cross, USA TODAY / USA TODAY Unlimited Use. USA TODAY Network via Reuters Connect.