Wildfire smoke degrades air quality in swaths of Ontario, with Toronto ranking among the worst in the world on Monday.

The National Weather Service’s Chicago office attributed the alert to unhealthy ozone levels and lingering effects of smoke ...

The Chicago area recorded ozone levels of 156 late Monday afternoon. Levels above 100 are considered unhealthy. Residents ...

The Illinois Environmental Protection Agency has issued an Air Pollution Action Day for Tuesday, July 15. Here's what to know ...

Meteorologist David Yeomans has the extended forecast.

CHICAGO (WLS) -- An air quality alert was issued by the National Weather Service for the Chicago area. Chopper 7 captured as ...

An air quality alert in the Chicago area will stretch into a third day as pollutants continue to linger in the air at high ...

CHICAGO - Today is warm with an air quality alert in effect. Sensitive groups should take it easy again as we have elevated ozone levels close to the ground. Highs will be around 90 this afternoon.

The alert comes as humidity is expected to increase Tuesday, with high temperatures in the mid 80s to low 90s, with heat indices reaching 100 by Wednesday.

The Illinois EPA declared an Air Pollution Action Day in the Chicago metro area. See today's air quality index forecast for Illinois.