Highest air pollution Gateway Arch - St. Louis, today and tomorrow
Today (29 June): Air quality in Gateway Arch is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 7:00 AM (O3: 35.7/100).
Tomorrow (30 June 2026): Air quality in Gateway Arch is fair. NO2 increases to fair; all other pollutants stay as today. Pollution peaks around 7:00 AM (O3: 38.0/100). Airmine updates local air quality forecasts four times daily.
For long term forecasts and maps, see the Airmine app
Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
St. Louis' Gateway Arch air quality benefits from the Mississippi River waterfront position, with the river's wide waterway providing limited natural ventilation around the extraordinary 192-metre stainless steel monument. Vehicle traffic on the surrounding I-44 and I-70 corridors contributes local sources, while the riverfront's open geometry provides reasonable dispersal and the Gateway Arch generally maintains moderate St. Louis metropolitan readings throughout most of the year.
Today - 29 June | Pollution peaks at 07:00
AQI:
Fair
35.7/100
PM2.5 (fine particles):
Good
13.3/100
PM10 (coarse particles):
Good
5.5/100
NO2 (nitrogen dioxide):
Good
17.8/100
O3 (ozone):
Fair
35.7/100
SO2 (sulfur dioxide):
Good
3.4/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
3.8/100
PM1 (ultrafine particles):
Good
9.8/100
Levels show the poorest local air quality during the day
Tomorrow - 30 June | Pollution peaks at 07:00
AQI:
Fair
38.0/100
PM2.5 (fine particles):
Good
13.0/100
PM10 (coarse particles):
Good
5.4/100
NO2 (nitrogen dioxide):
Fair
21.2/100
O3 (ozone):
Fair
38.0/100
SO2 (sulfur dioxide):
Good
3.3/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
5.9/100
PM1 (ultrafine particles):
Good
9.9/100
Other Landmarks in St. Louis
Frequently Asked Questions
Is air quality bad in Gateway Arch right now?
On 29 June 2026, overall air quality in Gateway Arch is fair. AQI is the main air quality indicator at 35.7/100. Pollution peaks around 7:00 AM (O3: 35.7/100).
Will air quality be worse tomorrow in Gateway Arch?
On 30 June 2026, air quality conditions in Gateway Arch will be similar to today, with AQI forecast at fair at 38.0/100. Pollution peaks around 7:00 AM (O3: 38.0/100).
Are air quality levels in Gateway Arch 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: 29 June 2026 at 18:38 CET (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
Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team