SmogRank / World / United States / Illinois / October 2023
Most polluted cities in Illinois, United States, October 2023
22 cities in Illinois, United States ranked by their average PM2.5 over the 31 days. Worst: Granite City at 10.9 µg/m³, #241 of 1,965 cities in the world. Cleanest: Winthrop Harbor at 6.0. 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.
- 1Granite City 0%
- 2East Saint Louis 0%
- 3Calumet City 0%
- 4Joliet 0%
- 4Oak Lawn 0%
- 4Rockford 0%
- 7Decatur 0%
- 8Naperville 0%
- 8Northbrook 0%
- 10Bloomington 0%
- 11Des Plaines 0%
- 12Jerseyville 0%
- 12Chicago 0%
- 14Braidwood 0%
- 14Franklin Park 0%
- 16Peoria 0%
- 17Moline 0%
- 18Springfield 0%
- 18Cary 0%
- 20Savoy 0%
- 21Wood River 0%
- 22Winthrop 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, October 2023, smogrank.com/us/region/illinois/history/2023-10 (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.