# World's Cleanest Cities

> Global ranking of 675 monitored cities by composite US AQI across PM2.5, PM10, NO2, ozone (O3) and CO — the most comprehensive multi-pollutant clean-air database freely available online.

World's Cleanest Cities (worldscleanestcities.com) ranks 675 cities across 7 continents using verified annual air quality measurements from the WHO Global Air Quality Database v6.1, US EPA AQS, CAMS Reanalysis and 20+ regional government monitoring networks. Data covers 2010–2024. Each city receives a composite US AQI calculated as the worst sub-index across all available pollutants. Seasonal charts, travel alerts, GDP productivity drag estimates, airport codes, tourist counts and relocation cost data are also provided.

## Rankings

- [Global Top 200 Cleanest Cities](https://worldscleanestcities.com/): The 200 cleanest monitored cities on Earth by composite US AQI, all continents combined.
- [Europe Rankings](https://worldscleanestcities.com/?continent=Europe): Top 250 cleanest cities in Europe — led by Longyearbyen (Svalbard), Mariehamn (Åland Islands) and Douglas (Isle of Man).
- [Oceania Rankings](https://worldscleanestcities.com/?continent=Oceania): Top 250 cleanest cities in Oceania — led by West Island (Cocos Keeling Islands), Flying Fish Cove (Christmas Island) and Kingston (Norfolk Island).
- [North America Rankings](https://worldscleanestcities.com/?continent=North+America): Top 250 cleanest cities in North America — led by Nuuk (Greenland), Saint-Pierre (Saint Pierre and Miquelon) and The Bottom (Saba).
- [Asia Rankings](https://worldscleanestcities.com/?continent=Asia): Top 250 cleanest cities in Asia — led by Obihiro, Asahikawa and Kochi (all Japan).
- [South America Rankings](https://worldscleanestcities.com/?continent=South+America): Top 250 cleanest cities in South America — led by Hanga Roa (Easter Island), Stanley (Falkland Islands) and Cayenne (French Guiana).
- [Africa & Middle East Rankings](https://worldscleanestcities.com/?continent=Africa+%26+Middle+East): Top 250 cleanest in Africa & Middle East — led by Georgetown (Ascension Island), Jamestown (Saint Helena) and Victoria (Seychelles).

## Key Facts

- [Full dataset details](https://worldscleanestcities.com/): 675 cities ranked; 570 cities have "Good" AQI (≤50); data spans 2010–2024.
- [Cleanest city globally](https://worldscleanestcities.com/): Longyearbyen, Svalbard — AQI 8, PM2.5 1.9 µg/m³ (WHO annual guideline: 5 µg/m³).
- [Cleanest major city](https://worldscleanestcities.com/): Hobart, Australia — AQI 20, PM2.5 4.5 µg/m³ among cities with population >200,000.
- [AQI scale](https://worldscleanestcities.com/): 0–50 Good (green) · 51–100 Moderate · 101–150 Unhealthy for Sensitive Groups · 151–200 Unhealthy · 201–300 Very Unhealthy · 300+ Hazardous.

## Data Sources

- [WHO Global Air Quality Database v6.1](https://www.who.int/data/gho/data/themes/air-pollution): Primary source for ground-station PM2.5 concentrations worldwide.
- [US EPA Air Quality System (AQS)](https://www.epa.gov/aqs): US city measurements for all 6 pollutants.
- [CAMS Reanalysis (Copernicus)](https://atmosphere.copernicus.eu/): Satellite-derived NO2, O3, PM10 backfill for cities lacking ground stations.
- Regional EPAs: Canada NAPS, Ireland EPA, UK DEFRA AURN, Norway Miljødirektoratet, Sweden SMHI, Belgium IRCEL, Switzerland BAFU, Japan MOE, Korea NIER, Australia State EPAs, New Zealand MfE, Mexico SINAICA, Chile SINCA, Brazil CETESB, and others.

## Optional

- [Full data file](https://worldscleanestcities.com/data/cities.json): Machine-readable JSON with all 675 cities, AQI, PM2.5, coordinates, population, cost of living, travel data and seasonal patterns.
- [LLMs full context](https://worldscleanestcities.com/llms-full.txt): Extended version of this file with top-50 city list, methodology, pollutant definitions and FAQ answers.