Cook County, Illinois
AQI 53 · Moderate53
Median AQI
94
90th Percentile
168
Max AQI
274
Days with Data
Ranked #23 of 23 counties in Illinois (by median AQI, lower is better)
Monthly Median AQI — 2025
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53
Median AQI
94
90th Percentile
168
Max AQI
274
Days with Data
Ranked #23 of 23 counties in Illinois (by median AQI, lower is better)
Click a bar to view that month's details