CHICAGO - Wildfire smoke is impacting millions of Americans, including Chicago.
The skies were especially hazy Wednesday, but there was still poor air quality Thursday.
Canadian wildfires are to blame, and they are creating a real health concern for many.
"The longer this goes on and the more frequently we're exposed to higher levels of particulate matter due to wildfires, the more health risks there are for the community in general," said Dr. Kalhan of the Northwestern Medicine Group.
Dr. Kalhan says the wildfire smoke is of most concern for people with chronic lung diseases, like COPD or asthma, or chronic heart conditions, along with children and the elderly.
However, healthy people can also suffer if they are outside for too long.