Worst air pollution O'Fallon, today and tomorrow
Today (16 July): Air quality in O'Fallon is fair. NO2 is fair; AQI and O3 are medium; PM2.5, PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 8:00 AM (O3: 48.6/100).
Tomorrow (17 July 2026): Air quality in O'Fallon is fair. All pollutants stay as today. Pollution peaks around 7:00 AM (O3: 51.8/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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O'Fallon's air quality benefits from the flat Missouri-Illinois river plain providing generally good wind dispersal, with vehicle emissions from I-64 and the surrounding mixed residential and commercial character of this major St. Louis western suburb contributing local sources. The St. Louis metropolitan regional ozone from vehicle and industrial sources is the primary warm-season concern, while the flat Midwest terrain generally maintains moderate conditions throughout the year.
Today - 16 July | Pollution peaks at 08:00
AQI:
Medium
48.6/100
PM2.5 (fine particles):
Good
17.3/100
PM10 (coarse particles):
Good
15.4/100
NO2 (nitrogen dioxide):
Fair
20.8/100
O3 (ozone):
Medium
48.6/100
SO2 (sulfur dioxide):
Good
4.1/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
8.4/100
PM1 (ultrafine particles):
Good
12.1/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 07:00
AQI:
Medium
51.8/100
PM2.5 (fine particles):
Good
17.3/100
PM10 (coarse particles):
Good
10.6/100
NO2 (nitrogen dioxide):
Fair
20.3/100
O3 (ozone):
Medium
51.8/100
SO2 (sulfur dioxide):
Good
3.4/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
9.8/100
PM1 (ultrafine particles):
Good
11.3/100
Pollen forecast in O'Fallon
View pollen forecastFrequently Asked Questions
Is air quality bad in O'Fallon right now?
On 16 July 2026, overall air quality in O'Fallon is fair. NO2 is the main pollutant at 20.8/100. Pollution peaks around 8:00 AM (O3: 48.6/100).
Will air quality be worse tomorrow in O'Fallon?
On 17 July 2026, air quality conditions in O'Fallon will be similar to today, with NO2 forecast at fair at 20.3/100. Pollution peaks around 7:00 AM (O3: 51.8/100).
When is air pollution at its worst in O'Fallon?
O'Fallon sees air quality change through the year. In short, winter generally brings the cleanest air, aside from brief inversion episodes during calm cold spells, whereas both spring planting and autumn harvest bring short bursts of elevated dust and smoke. Wide-open terrain generally helps disperse pollution quickly once the wind picks up.
Are air quality levels in O'Fallon based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
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Data provided by Airmine — Last update: 16 July 2026 at 10:33 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
For long term forecasts and maps, see the Airmine app