EPA AirNow — Real-Time Air Quality
Real-time air-quality observations from ~5,000 US monitoring stations (PM2.5, PM10, O3, NO2, SO2, CO). Hourly cadence. Authoritative regulator-grade source for AQ advisories.
| Provider | US EPA / NOAA / NPS / tribes / states |
|---|---|
| Delivery mode | stream |
| CNR score | 78 |
| Cadence | PT1H |
| Origin | https://www.airnow.gov/ |