How is air quality measured?

As smoky air from Canada’s wildfires shrouds broad swaths of the U.S., here are seven facts you should know about measuring air quality.

What you need to know about Thursday's heat index in Chicago

The combination of heat and humidity we experience in Chicago can be deadly during the summer. The number of days per year we will be at risk from extreme heat could soar by the middle of this century.

Chicago weather: Awful air quality continues Wednesday
video

The smoke for wildfires raging in Canada continues to affect air quality in the Midwest, especially in the Chicago area. On top of the smoke, Chicago will have some sweltering temperatures in the coming days.

A breakdown of smoky skies across Chicago
video

The smoke has led to air quality alerts to be issued in Chicago and throughout the Midwest.

Chicago's air quality is worst in the world Tuesday due to smoke: index

Heavy smoke from Canadian wildfires settled into a curtain of thick haze covering the Chicago area Tuesday, leading to air quality warnings.