---
license: cc0-1.0
task_categories:
- other
language:
- en
tags:
- air-quality
- epa
- environment
- united-states
- hourly
pretty_name: US Hourly Air Quality (EPA AQS) 2015–2024
size_categories:
- 100M<n<1B
---

# US Hourly Air Quality (EPA AQS) 2015–2024

Hourly air quality readings from all US EPA monitoring stations, 2015–2024.

## Dataset Details

239M+ rows covering 6 NAAQS criteria pollutants across all US monitoring stations for 10 years.

### Fields

| Column | Description |
|---|---|
| `timestamp` | Local date and time of measurement |
| `pollutant` | Pollutant name: ozone, pm25, pm10, so2, co, no2 |
| `value` | Raw measurement value |
| `unit` | Unit of measurement |
| `aqi` | Calculated AQI (EPA standard breakpoints) |
| `state_name` / `state_code` | State name and FIPS code |
| `county_name` / `county_code` | County name and FIPS code |
| `site_num` | EPA monitoring site number |
| `latitude` / `longitude` | Station coordinates |
| `mdl` | Method detection limit |
| `datum` | Coordinate datum |

### Pollutants

| Value | Pollutant |
|---|---|
| `ozone` | Ozone (O₃) |
| `pm25` | Fine particulate matter (PM2.5) |
| `pm10` | Coarse particulate matter (PM10) |
| `so2` | Sulfur dioxide |
| `co` | Carbon monoxide |
| `no2` | Nitrogen dioxide |

## Source

[EPA Air Quality System (AQS)](https://aqs.epa.gov/aqsweb/airdata/download_files.html) — bulk hourly data files. No API key required.

## License

EPA data is in the public domain (US Government Work). Released as CC0.