Air quality in St. Louis today
The air in St. Louis (United States) now and over the next 48 hours: the US AQI and the European AQI, fine particles (PM2.5, PM10), ozone and nitrogen dioxide, compared with the WHO 2021 guidelines, with what it means for outdoor sport, children, older people and open windows.
These numbers are more than 7 hours old, so they are hidden. Open the live map for the current air. Open the air map centred on St. Louis
AQI right now
Good. Main pollutant: Ozone (O₃) (all pollutants within the WHO guidelines).
What to do today
- Outdoor sport Go ahead: running, cycling and play outside carry no air-quality risk.
- Children, older people, asthma No restrictions.
- Windows Open them and air the rooms.
AQI in St. Louis hour by hour, next 48 hours
- Good
- Moderate
- Unhealthy for sensitive groups
- Unhealthy
- Very unhealthy
- Hazardous
Cleanest hour in the next 24 h: Sat 19:00 (AQI 46). Worst hour: Sun 15:00 (AQI 54).
US AQI per hour, local time. Bars coloured by category.
Compared with the WHO 2021 guidelines
| Pollutant | Next 24 h | WHO guideline | Ratio |
|---|---|---|---|
| PM2.5 | 11 µg/m³ | 15 µg/m³ | within |
| PM10 | 11 µg/m³ | 45 µg/m³ | within |
| Nitrogen dioxide (NO₂) | 17 µg/m³ | 25 µg/m³ | within |
| Ozone (O₃) | 97 µg/m³ | 100 µg/m³ | within |
PM2.5, PM10 and NO₂: 24-hour mean of the forecast against the 24-hour guideline; ozone: highest 8-hour mean against the 8-hour guideline.
Forecast for Sat 19:00 local time · updated 2026-10-25 00:41 UTC
Air quality map around St. Louis
Live PM2.5 field (NOAA GEFS-Aerosols): a different model, so it can disagree with the numbers above by a few units.
More about St. Louis
Bad air alert for St. Louis
Air quality alerts are part of LayEarth Pro: one push the evening before the forecast US AQI in your city goes above your level, so you can move a run, a school trip or an open window in time. 7-day free trial, then 9 USD a month.
Questions
- What is the AQI in St. Louis right now?
- US AQI 46 (Good), European AQI 34; PM2.5 9.6 µg/m³ (Sat 19:00).
- Is it safe to exercise outdoors in St. Louis today?
- Go ahead: running, cycling and play outside carry no air-quality risk.
- What is the main pollutant in St. Louis?
- Ozone (O₃) (all pollutants within the WHO guidelines).
- Where do the numbers come from?
- The CAMS global air-quality forecast of the Copernicus Atmosphere Monitoring Service, read through Open-Meteo: a model on a ~40 km grid, not a monitoring station. Where a nearby monitor disagrees, the monitor is right.
Nearby cities
Indianapolis · Kansas City · Memphis · Nashville · Chicago · Cincinnati
How it is computed
Hourly CAMS forecast (Copernicus) for the coordinates of St. Louis via Open-Meteo; US AQI per the US EPA breakpoints, European AQI per the EEA bands, WHO 2021 air-quality guidelines. The page is rebuilt every 3 hours. Live map.