Chicago will enter its second day of an Air Pollution Action Day alert on Wednesday.
Tuesday’s air-quality index hit 122, and the unhealthy levels are expected to persist into Wednesday evening across the Chicago metro area and northwest Indiana, the National Weather Service said.
The ‘poor air quality’ category is said to be a result of unhealthy ozone levels and some lingering effects of Canadian wildfire smoke.
[2:30 PM 7/15/2025] An Air Quality Alert is now in effect through Wed. evening for the Chicago metro area and in NW Indiana due to unhealthy ozone levels and some lingering effects of Canadian wildfire smoke. Air quality is expected to be at unhealthy levels for sensitive groups. pic.twitter.com/pmSwIM7pFq
— NWS Chicago (@NWSChicago) July 15, 2025
“Sensitive individuals should take special precautions and follow their physician-prescribed regimen. In addition, some minority groups, people with lower incomes, and outdoor workers may experience higher exposure that can worsen health conditions,” the Illinois EPA said in a statement Tuesday.
The Air Pollution Action Day alert is triggered when air pollution levels reach the “orange” or “unhealthy for sensitive groups” category on the national Air Quality Index.
Air-quality levels between 101 and 150 are unhealthy for sensitive groups like those with pre-existing respiratory conditions, babies, children and the elderly. Air-quality levels below 100 are considered healthy.
The weather Tuesday evening into Wednesday is expected to include a few storms that could bring high winds and heavy rain. Wednesday is expected to be partly cloudy with possible severe storms in the afternoon and a high of 91 and a low of 70, according to ABC7 meteorologist Cheryl Scott.