CHICAGO (WLS) -- An air quality alert has been extended for part of the Chicago area through Thursday.

The alert for McHenry, Lake, Kane, DuPage, Kendall, Grundy, Cook and Will counties in Illinois and some of southern Wisconsin lasts until midnight Friday.

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The Illinois Environmental Protection Agency previously issued an Air Pollution Action Day for Wednesday for the Chicago area.

Lake, Porter, Newton and Jasper counties in Indiana are also under alert all day Tuesday.

The alert was also issued because of unhealthy ozone levels in addition to smoke particles.

The Chicago area has been under air quality alerts for most of last week, due to smoke from Canadian wildfires.

At one point last week, Chicago had the worst air qualit

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