What is the air quality trend in Alton?

Over the past 2 days, Alton had an average AQI of 55 based on station measurements. The worst day was 2026-07-20 with AQI 62.

How is Alton air quality measured?

Air quality in Alton 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 Alton, United States

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

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

Current AQI
Moderate CAMS model

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

42h

PM2.5 Station

42h · 6 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-07-21	49	25–69	12.7 µg/m³	22h	3
2026-07-20	62	23–106	18.5 µg/m³	20h	4

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