SmogRank / World / United States / Illinois / 2026
Most polluted cities in Illinois, United States, 2026
31 cities in Illinois, United States ranked by their average PM2.5 so far (278 of 365 days); 31 above the WHO annual guideline (5.0 µg/m³). Worst: Elmwood Park at 13.0 µg/m³, #663 of 2,745 cities in the world. Cleanest: Bloomington at 7.1. 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 3%
- 2Elgin 2%
- 3Winthrop Harbor 2%
- 4Northbrook 2%
- 5Dolton 1%
- 6Bridgeview 1%
- 7Calumet City 1%
- 7Oak Lawn 1%
- 9Lincolnwood 1%
- 10Braidwood 1%
- 11Brookfield 1%
- 12Des Plaines 1%
- 13Joliet 1%
- 14Franklin Park 1%
- 15Chicago 1%
- 16Naperville 1%
- 17Rockford 1%
- 18Warrenville 1%
- 19Cary 1%
- 20Champaign 1%
- 21Peoria 1%
- 22Savoy 1%
- 23Springfield 1%
- 24Decatur 1%
- 25Moline 1%
- 26Bloomington 1%
- 27Jerseyville 0%
- 28Wood River 0%
- 29Upper Alton 0%
- 30Granite City 0%
- 31East Saint Louis 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, 2026 (so far), smogrank.com/us/region/illinois/history/2026 (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.