SmogRank / World / United States / Illinois / August 2025
Most polluted cities in Illinois, United States, August 2025
31 cities in Illinois, United States ranked by their average PM2.5 over the 31 days. Worst: Elmwood Park at 17.0 µg/m³, #265 of 2,841 cities in the world. Cleanest: Champaign at 9.0. A city needs measurements on 70% of the days to be ranked.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
- 1Elmwood Parklow-cost sensors 13%
- 2Franklin Park 10%
- 3Winthrop Harbor 10%
- 4Des Plaines 6%
- 5Elgin 6%
- 5Rockford 6%
- 7Cary 6%
- 8Lincolnwood 4%
- 9Northbrook 4%
- 10Bridgeview 3%
- 11Calumet City 3%
- 12Oak Lawn 3%
- 13Warrenville 3%
- 14Chicago 3%
- 15Brookfield 3%
- 15Dolton 3%
- 17Moline 3%
- 17Naperville 3%
- 19Wood River 3%
- 20Peoria 3%
- 21Joliet 3%
- 22East Saint Louis 3%
- 23Granite City 3%
- 24Upper Alton 3%
- 25Springfield 3%
- 26Decatur 3%
- 27Braidwood 3%
- 28Jerseyville 3%
- 28Bloomington 3%
- 28Savoy 3%
- 31Champaign 3%
Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
All cities in the world, August 2025 · All cities in United States, August 2025 · Illinois now
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SmogRank, most polluted cities in Illinois, United States, PM2.5, August 2025, smogrank.com/us/region/illinois/history/2025-08 (accessed 6 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.