SmogRank / World / United States / Illinois / 2025
Most polluted cities in Illinois, United States, 2025
30 cities in Illinois, United States ranked by their average PM2.5 over the 365 days; 30 above the WHO annual guideline (5.0 µg/m³). Worst: Elmwood Park at 13.6 µg/m³, #486 of 2,624 cities in the world. Cleanest: Jerseyville at 6.7. 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 5%
- 2Franklin Park 2%
- 3Dolton 2%
- 4Winthrop Harbor 2%
- 5Lincolnwood 2%
- 6Des Plaines 2%
- 7Braidwood 1%
- 8Oak Lawn 1%
- 9Rockford 1%
- 10Peoria 1%
- 11Calumet City 1%
- 12Elgin 1%
- 13Joliet 1%
- 14Cary 1%
- 15Naperville 1%
- 16Northbrook 1%
- 17Warrenville 1%
- 18Chicago 1%
- 19Springfield 1%
- 19Bloomington 1%
- 21Upper Alton 1%
- 22Brookfield 1%
- 23Granite City 1%
- 24East Saint Louis 1%
- 25Wood River 1%
- 26Moline 1%
- 27Decatur 1%
- 28Champaign 1%
- 29Savoy 1%
- 30Jerseyville 0%
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
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SmogRank, most polluted cities in Illinois, United States, PM2.5, 2025, smogrank.com/us/region/illinois/history/2025 (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.