Loftgæði (Air Quality) — UST / Reykjavik

Requires: Tier 0 (core).

PM10, PM2.5, NO2, SO2, H2S monitoring via Umhverfisstofnun (Environment Agency).

API

Base URL: https://api.ust.is/aq/a/

No authentication required. Returns JSON. CORS enabled.

Endpoints

Endpoint	Description
getStations	All stations with coordinates, parameters, activity dates
getStation/{local_id}	Single station metadata
getLatest	Last 24h for all stations
getCurrent/{local_id}	Last 24h for one station
getDate/date/{YYYY-MM-DD}	All stations, all params, one day (hourly)

Response Structure (getDate)

{
  "STA-IS0005A": {
    "name": "Reykjavik Grensas",
    "local_id": "STA-IS0005A",
    "parameters": {
      "PM10": {
        "unit": "µg/m3",
        "resolution": "1h",
        "0": { "endtime": "2024-03-15 23:00:00", "value": "42.5", "verification": 3 },
        ...
      }
    }
  }
}

Values are strings — cast to float. Numbered keys (0, 1, ...) are hourly readings.

Key Reykjavik Stations

Station	local_id	Type	Active
Grensásvegur	STA-IS0005A	traffic	1990–
Húsdýragarðurinn	STA-IS0006A	background	2002–
Norðlingaholt	STA-IS0022A	industrial	2011–
Laugarnes	STA-IS0061A	industrial	2021–

Primary station for PM10/nagladekk (studded tire) analysis: Grensásvegur (traffic station on major road).

Pollutants

Parameter	Relevance
PM10	Spring dust from studded tires. EU 24h limit: 50 µg/m³
PM2.5	Fine particles. EU annual limit: 25 µg/m³
NO2	Traffic. EU 1h limit: 200 µg/m³
H2S	Geothermal (Hellisheiði). Nuisance smell at 5 µg/m³

Fetching Historical Data

Bulk CSVs (preferred for past years)

Annual CSVs at https://api.ust.is/static/aq/ust_aq_timeseries_{YEAR}.csv (62-113 MB each).

• Available: 2015–2024 (no 2025 yet as of Feb 2026)
• Columns: station_name, pollutantnotation, local_id, endtime, the_value, resolution, verification, validity, station_local_id, concentration
• Date formats vary: YYYY-MM-DD HH:MM:SS (2015-2021) and DD/MM/YYYY HH:MM:SS (2022+)
• Filter: station_local_id == "STA-IS0005A" and pollutantnotation == "PM10"
• Sensor errors: filter the_value < 2000 (values >2000 are instrument faults)

Per-day API (for current year)

import httpx

def fetch_pm10_day(date_str: str, station: str = "STA-IS0005A") -> list[dict]:
    """Fetch hourly PM10 for one day. date_str: YYYY-MM-DD"""
    url = f"https://api.ust.is/aq/a/getDate/date/{date_str}"
    resp = httpx.get(url, timeout=30)
    data = resp.json()
    station_data = data.get(station, {})
    pm10 = station_data.get("parameters", {}).get("PM10", {})
    rows = []
    for k, v in pm10.items():
        if isinstance(v, dict) and "value" in v:
            rows.append({"datetime": v["endtime"], "pm10": float(v["value"])})
    return rows

Rate limiting: No documented limits. Use 0.15s delay between requests.

Pre-built script

uv run python scripts/loftgaedi.py — downloads bulk CSVs + API for recent data, outputs data/processed/reykjavik_pm10_daily.csv with PM10 + wind + weather joined.

Reykjavik loftapi (alternative, currently down)

Base URL: http://loftapi.reykjavik.is/api/v1/stations/data/{station}/{pollutant}/{start}/{sh}/{sm}/{end}/{eh}/{em}

• Station 02 = Grensásvegur, pollutant 91 = PM10
• Date format: DD-MM-YYYY
• As of Feb 2026: connection times out. Use UST API instead.

Wind Data (for dust correlation)

Use Open-Meteo for historical daily wind speed in Reykjavik:

https://archive-api.open-meteo.com/v1/archive?latitude=64.13&longitude=-21.90&start_date=2024-01-01&end_date=2024-12-31&daily=wind_speed_10m_max,wind_speed_10m_mean,precipitation_sum&timezone=Atlantic/Reykjavik

Low wind + dry = high PM10 (dust not dispersed). High wind can also resuspend settled dust.

Caveats

1. getDate is slow for bulk — one HTTP request per day. Multi-year fetch takes hours.
2. Missing data — some days return no PM10 readings (maintenance, sensor issues)
3. Verification field — 3 = unverified real-time, 1 = verified. Historical data may be adjusted.
4. Grensásvegur bias — traffic station, reads higher than background. Compare with Húsdýragarðurinn for urban background.