# World's Cleanest Cities

> Ranking of 5856 cities in 242 countries and territories by US AQI from PM2.5, PM10 and ozone, month by month over each city's full record (1994–October 2026), using government air-quality monitoring data where available.

World's Cleanest Cities (worldscleanestcities.com) ranks 5856 cities. For each month of each year, the US EPA AQI (2024 breakpoints) of the worst of PM2.5, PM10 and ozone (daily maximum 8-hour) is taken; each calendar month's AQI is averaged over the city's full record (every month-year with a monitor, low-cost sensor or satellite PM2.5 value, 1994–October 2026; usually 1998–2024 plus 2025–2026 months where monitors or sensors report them) and the city's AQI is the average of the 12 months. 2025–2026 data are provisional where agencies haven't finalised them. Lower = cleaner. 2168 cities use government monitoring data for PM2.5 (US EPA Air Quality System (1994–2026); European Environment Agency (1998–2026); Luchtmeetnet, Dutch national air-quality network (government monitors not in the EEA file) (2014–2026); Environment and Climate Change Canada NAPS (1997–2026); Japan Ministry of the Environment / NIES (1998–2026); Thailand Pollution Control Department (government monitors; ozone from PCD hourly data archived by OpenAQ) (2011–2026); Singapore National Environment Agency (2016–2026); Mexico SINAICA (1998–2026); Mexico SINAICA stations, gaps filled from the OpenAQ archive copy (2016–2026); Brazil MonitorAr / state agencies (2022–2025); CETESB São Paulo state monitors, ozone concentrations recovered from the hourly air-quality index (MonitorAr) (2022–2025); CETESB São Paulo state monitors, measured concentrations (via OpenAQ archive, to March 2023) (2017–2023); UK Defra Automatic Urban and Rural Network (1998–2026); Korea AirKorea / NIER (2001–2026); Taiwan Ministry of Environment (1997–2026); Australian state EPAs — NSW, Victoria, Queensland, South Australia, ACT (1996–2026); New Zealand regional councils (1998–2026); Bogotá Air Quality Monitoring Network, RMCAB (1998–2026); Colombia IDEAM SISAIRE national air-quality records (2020–2025); Buenos Aires Environmental Protection Agency, APrA (government monitors, PM10 only) (2009–2026); China national monitoring network (CNEMC), archived real-time data (quotsoft.net) (2014–2026); India Central Pollution Control Board CAAQMS (government monitors; CPCB data via the india-cpcb-aqi mirror, ODbL) (2009–2026); India CPCB monitors, ozone (known to read low in some cities; ODbL) (2009–2026); Hong Kong Environmental Protection Department (1998–2026); Intendencia de Montevideo air-quality network (2014–2025); Bangladesh Department of Environment CAMS (government monitors, via CAMS-BD dataset, CC BY 4.0) (2012–2024); Georgia National Environmental Agency (2019–2026); Argentina national environment office CIAM (government monitors, monthly PM10) (2023–2024); US EPA monitors across the border, same urban area ≤ 10 km (2005–2026); Chile Ministry of the Environment SINCA (government monitors, via OpenAQ archive) (2016–2026); Türkiye Ministry of Environment, Urbanisation and Climate Change national air-quality network (government monitors, via OpenAQ, Dec 2016 – Oct 2023) (2022–2023); Hanoi Department of Natural Resources and Environment air-quality network (government monitors, via OpenAQ) (2024–2026); South African Air Quality Information System, SAAQIS (government monitors; SAAQIS public reports, gaps filled via OpenAQ) (2004–2026); Environment Agency – Abu Dhabi air-quality network (government monitors, via OpenAQ) (2023–2024); Kosovo Hydrometeorological Institute air-quality network (government monitors, via OpenAQ) (2019–2025); London Air Quality Network, Surrey/Sussex borough sites (government monitors, via OpenAQ archive; UK OGL v2) (2021–2023); HungaroMet Air Quality Network, OLM (government monitors, via OpenAQ archive) (2023–2026); Thailand Pollution Control Department Air4Thai (government monitors, via OpenAQ archive) (2022–2024); Peru SENAMHI Lima network (government monitors, Peru open-data portal) (2015–2026); Peru OEFA air-quality vigilance stations, Chimbote area (government monitors in an industrial area; Peru open-data portal, and OEFA real-time data via OpenAQ) (2019–2024); US State Department embassy monitors, via US EPA AirNow (2015–2026)); 11 use calibrated low-cost sensors; the rest use satellite-derived PM2.5 (Washington University ACAG, calibrated to ground monitors), with the Copernicus CAMS model for ozone and PM10 where no monitor exists, labelled as such on each city page. No WHO database values are used. Monthly charts, travel alerts and relocation data are also provided.

## Rankings

- [Global ranking](https://worldscleanestcities.com/): All 5856 cities, cleanest first.
- [Europe](https://worldscleanestcities.com/?continent=Europe): 859 cities — cleanest: Longyearbyen (30), Murmansk (30), Kiruna (31).
- [North America](https://worldscleanestcities.com/?continent=North+America): 833 cities — cleanest: Nuuk (21), Lihue HI (27), Kahului HI (27).
- [Asia](https://worldscleanestcities.com/?continent=Asia): 2468 cities — cleanest: Norilsk (31), Novy Urengoy (35), Petropavlovsk-Kamchatsky (36).
- [Oceania](https://worldscleanestcities.com/?continent=Oceania): 77 cities — cleanest: Papeete (15), Avarua (16), Pago Pago (16).
- [South America](https://worldscleanestcities.com/?continent=South+America): 629 cities — cleanest: Hanga Roa (15), Stanley (20), Porto Seguro (25).
- [Africa & Middle East](https://worldscleanestcities.com/?continent=Africa+%26+Middle+East): 990 cities — cleanest: Jamestown (18), Georgetown (21), Victoria (24).

## Policy Proposal

- [A Proposal to World Governments](https://worldscleanestcities.com/proposal): A policy document making the economic case for a $250 billion Global Clean-Air Technology Fund, citing peer-reviewed studies. Covers the 7.9 million deaths from air pollution in 2023 (State of Global Air 2025), the $8.1 trillion yearly health cost of fine-particle pollution (World Bank, 2019 data), source sectors, technology costs, the Montreal Protocol precedent and a phased deployment plan. Available in 13 languages.

## Methodology

- [Data Methodology & Sources](https://worldscleanestcities.com/methodology): Data sources, station selection rules, the EPA AQI formula and breakpoints, the monthly ranking method, data checks and known limitations.

## Key Facts

- Cleanest city: Hanga Roa, Easter Island — AQI 15 (Excellent), PM2.5 1.9 µg/m³, satellite data.
- Cleanest city of 200,000+ people with government monitor data: Urban Honolulu HI, United States of America — AQI 27 (Excellent), PM2.5 4.3 µg/m³, government monitors.
- Site colour bands: 0–30 Excellent (green), 31–60 Reasonable (yellow), 61+ Polluted (red). The underlying number is the standard EPA AQI.
- Air pollution deaths: about 7.9 million in 2023 from outdoor and household air pollution and ozone, 4.9 million of them from outdoor fine particles (State of Global Air 2025). WHO's own count, for 2021, is 6.6 million (outdoor and household fine particles; it does not include ozone).

## Data Sources

- US EPA Air Quality System (1994–2026)
- European Environment Agency (1998–2026)
- Luchtmeetnet, Dutch national air-quality network (government monitors not in the EEA file) (2014–2026)
- Environment and Climate Change Canada NAPS (1997–2026)
- Japan Ministry of the Environment / NIES (1998–2026)
- Thailand Pollution Control Department (government monitors; ozone from PCD hourly data archived by OpenAQ) (2011–2026)
- Singapore National Environment Agency (2016–2026)
- Mexico SINAICA (1998–2026)
- Mexico SINAICA stations, gaps filled from the OpenAQ archive copy (2016–2026)
- Brazil MonitorAr / state agencies (2022–2025)
- CETESB São Paulo state monitors, ozone concentrations recovered from the hourly air-quality index (MonitorAr) (2022–2025)
- CETESB São Paulo state monitors, measured concentrations (via OpenAQ archive, to March 2023) (2017–2023)
- UK Defra Automatic Urban and Rural Network (1998–2026)
- Korea AirKorea / NIER (2001–2026)
- Taiwan Ministry of Environment (1997–2026)
- Australian state EPAs — NSW, Victoria, Queensland, South Australia, ACT (1996–2026)
- New Zealand regional councils (1998–2026)
- Bogotá Air Quality Monitoring Network, RMCAB (1998–2026)
- Colombia IDEAM SISAIRE national air-quality records (2020–2025)
- Buenos Aires Environmental Protection Agency, APrA (government monitors, PM10 only) (2009–2026)
- China national monitoring network (CNEMC), archived real-time data (quotsoft.net) (2014–2026)
- India Central Pollution Control Board CAAQMS (government monitors; CPCB data via the india-cpcb-aqi mirror, ODbL) (2009–2026)
- India CPCB monitors, ozone (known to read low in some cities; ODbL) (2009–2026)
- Hong Kong Environmental Protection Department (1998–2026)
- Intendencia de Montevideo air-quality network (2014–2025)
- Bangladesh Department of Environment CAMS (government monitors, via CAMS-BD dataset, CC BY 4.0) (2012–2024)
- Georgia National Environmental Agency (2019–2026)
- Argentina national environment office CIAM (government monitors, monthly PM10) (2023–2024)
- US EPA monitors across the border, same urban area ≤ 10 km (2005–2026)
- Chile Ministry of the Environment SINCA (government monitors, via OpenAQ archive) (2016–2026)
- Türkiye Ministry of Environment, Urbanisation and Climate Change national air-quality network (government monitors, via OpenAQ, Dec 2016 – Oct 2023) (2022–2023)
- Hanoi Department of Natural Resources and Environment air-quality network (government monitors, via OpenAQ) (2024–2026)
- South African Air Quality Information System, SAAQIS (government monitors; SAAQIS public reports, gaps filled via OpenAQ) (2004–2026)
- Environment Agency – Abu Dhabi air-quality network (government monitors, via OpenAQ) (2023–2024)
- Kosovo Hydrometeorological Institute air-quality network (government monitors, via OpenAQ) (2019–2025)
- London Air Quality Network, Surrey/Sussex borough sites (government monitors, via OpenAQ archive; UK OGL v2) (2021–2023)
- HungaroMet Air Quality Network, OLM (government monitors, via OpenAQ archive) (2023–2026)
- Thailand Pollution Control Department Air4Thai (government monitors, via OpenAQ archive) (2022–2024)
- Peru SENAMHI Lima network (government monitors, Peru open-data portal) (2015–2026)
- Peru OEFA air-quality vigilance stations, Chimbote area (government monitors in an industrial area; Peru open-data portal, and OEFA real-time data via OpenAQ) (2019–2024)
- US State Department embassy monitors, via US EPA AirNow (2015–2026)
- Low-cost sensors (AirGradient, Clarity, IQAir, PAQI, senstate, sensors.AFRICA, Sensor.Community; via OpenAQ, openAFRICA, sensor.community), Plantower sensors EPA-corrected; used only in months with no government monitor value
- Satellite-derived PM2.5, WUSTL ACAG V6.GL.03 (where no government monitor exists)
- Copernicus CAMS global model via Open-Meteo (ozone and PM10 where no government monitor exists)
- Comparison only, not used for any value: WHO Ambient Air Quality Database version 8.0 (June 2026). Where cities have government monitors, the site's yearly PM2.5 is within 10% of WHO's for 88.2% of 7,466 city-years in 964 cities (median difference 0.1%; Brazil left out because WHO's Brazil rows are daily-maximum values).

## Optional

- Licence: CC BY 4.0, except figures derived from India CPCB (india-cpcb-aqi) and Sensor.Community data, which are under ODbL 1.0.
- [Ranking data file](https://worldscleanestcities.com/data/cities.json): Machine-readable JSON with every city's AQI, rank, monthly composite AQI, annual pollutant values and the source and years of each number.
- Per-city data files (https://worldscleanestcities.com/data/city/<slug>.json, slug given for each city in cities.json): the full record behind each city, with monthly PM2.5, PM10 and ozone, best areas to stay, worst months and relocation data.
- [LLMs full context](https://worldscleanestcities.com/llms-full.txt): Extended version with the top 50 cities and per-region leaders.