Smoke from Canadian wildfires dimmed the downtown Chicago skyline on Tuesday. The smoke is causing air quality alerts in parts of Minnesota, Iowa and Wisconsin and is visible in Illinois, Michigan, Ohio, Pennsylvania and West Virginia. (Scott Olson/Getty Images)

By Ian Livingston

Chicagoland woke up to code red unhealthy air quality Thursday as wildfire smoke from Canada continues to plague the Upper Midwest and Great Lakes region. For a time early in the day, it had the second-worst air quality among the world’s major cities.

Air quality alerts covered all of Michigan and portions of Wisconsin, Illinois, Indiana and Nebraska. Detroit had the fourth-worst air among major cities worldwide as of Thursday morning. Other cities under the alerts included Flint and Grand Rapids in Michigan, M

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