What is the air quality trend in Chicago?

Over the past 7 days, Chicago had an average AQI of 36 based on station measurements. The worst day was 2026-05-24 with AQI 52.

How is Chicago air quality measured?

Air quality in Chicago is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Chicago, United States

Name: Chicago Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Chicago, United States.

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

166h

PM2.5 Station

166h · 8 stations

Temperature GFS model

27pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-05-28	27	22–39	6.5 µg/m³	23h	255
2026-05-27	43	30–58	10.6 µg/m³	24h	279
2026-05-26	33	27–44	7.9 µg/m³	24h	278
2026-05-25	48	31–71	12.9 µg/m³	24h	280
2026-05-24	52	38–59	13.0 µg/m³	24h	279
2026-05-23	28	21–37	6.6 µg/m³	24h	277
2026-05-22	24	19–27	5.6 µg/m³	23h	266

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