SmogRank / World / United States / Illinois / September 2023
Most polluted cities in Illinois, United States, September 2023
21 cities in Illinois, United States ranked by their average PM2.5 over the 30 days. Worst: East Saint Louis at 13.1 µg/m³, #237 of 2,128 cities in the world. Cleanest: Winthrop Harbor 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.
- 1East Saint Louis 0%
- 2Springfield 0%
- 3Jerseyville 0%
- 4Granite City 0%
- 5Franklin Park 0%
- 6Calumet City 0%
- 7Naperville 0%
- 8Decatur 0%
- 9Northbrook 0%
- 10Moline 0%
- 10Rockford 0%
- 12Bloomington 0%
- 12Des Plaines 0%
- 14Peoria 0%
- 15Joliet 0%
- 16Chicago 0%
- 17Braidwood 0%
- 18Cary 0%
- 19Savoy 0%
- 20Oak Lawn 0%
- 21Winthrop Harbor 0%
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, September 2023, smogrank.com/us/region/illinois/history/2023-09 (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.