What is the air quality trend in St. Louis?

Over the past 14 days, St. Louis had an average AQI of 49 based on station measurements. The worst day was 2026-07-17 with AQI 101.

How is St. Louis air quality measured?

Air quality in St. Louis 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 St. Louis, United States

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

328h

PM2.5 Station

328h · 5 stations

Temperature GFS model

56pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-07-21	51	25–69	13.3 µg/m³	22h	3
2026-07-20	61	18–106	18.3 µg/m³	21h	4
2026-07-19	61	18–135	18.3 µg/m³	23h	4
2026-07-18	63	20–140	18.7 µg/m³	23h	4
2026-07-17	101	18–176	41.1 µg/m³	24h	5
2026-07-16	72	32–152	22.5 µg/m³	24h	5
2026-07-15	52	30–94	14.2 µg/m³	24h	5
2026-07-14	42	15–54	10.1 µg/m³	24h	5
2026-07-13	35	25–56	8.4 µg/m³	23h	5
2026-07-12	35	12–75	8.7 µg/m³	24h	4
2026-07-11	33	9–52	8.0 µg/m³	24h	4
2026-07-10	28	11–39	6.6 µg/m³	24h	5
2026-07-09	31	9–43	7.5 µg/m³	24h	5
2026-07-08	31	22–40	7.4 µg/m³	24h	6

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