Air pollution is one of the leading causes of death around the world. Therefore you may be curious: “What are the least polluted cities in the world?”. Or which country has the least amount of air pollution? Smart Air analyzed 2021 air pollution data from 540 major cities spanning 182 countries in the world to create the 2021 ranking of the “25 Least Polluted Cities in the World”. So, which cities and countries had the cleanest air?
Rankings: 25 Cities with the Cleanest Air in the World
Read on for the full list of 25 cities and an analysis of what this data means.
1. Zurich, Switzerland
2. Hobart, Australia
3. Reykjavik, Iceland
4. Launceston, Australia
5. Honolulu, US
6. Vitoria, Brazil
7. Bergen, Norway
8. Wollongong, Australia
9. Turku, Finland
10. Funchal, Portugal
11. Edinburgh, Scotland
12. Upsala, Sweden
13. Halifax, Canada
14. Trondheim, Norway
15. Castellón de la Plana, Spain
16. Tampere, Finland
17. Adelaide, Australia
18. Vancouver, Canada
19. Glasgow, Scotland
20. Oulu, Finland
21. Brisbane, Australia
22. Gothenburg, Sweden
23. Surrey, Canada
24. Sydney, Australia
25. Newcastle, Australia
Of the 25 least polluted cities in the world with the best air quality, Nordic countries (Finland, Sweden, Norway, Iceland) dominated the rankings. 8 out of the 25 cities with the best and cleanest air were Nordic countries. Australia topped the list as least polluted country in the world, with 7 cities in the top 25. Switzerland is ranked as one of the least polluted countries in the world. Australia, Canada, and Finland were the only countries having at least 3 cities ranking in the top 25 cities with the cleanest, least polluted air.
Comparing with the previous year, Australian cities saw an improvement in rankings with only 2 cities in 2020 to 7 in 2021. On the other hand, Nordic countries saw a drop in the number cities from 10 to 8. Zurich, Switzerland, remains top on the list for both years.
Even though these are some of the cities with the best air quality in the world, each city experienced times during 2021 where pollution was over the WHO recommended limit. This shows how serious air pollution is all across the world. There is also research that even little amounts of pollution such as those typically present in these least polluted cities can have an impact on health.
Below is a pollution heat map from the WHO. WHO research shows that over 92% of people in the world are breathing unsafe air with high air pollution levels.
How Air Pollution Was Measured to Find Least Polluted Cities in World
There are various pollutants (both particles and gases) that can be found in the air. One of the most commonly tracked pollutants are very small, fine particles called PM2.5.
These small pollutants are under 2.5 micrograms in width and considered to be one of the more dangerous pollutants due to their ability to enter deep into the lungs and bloodstream. The above rankings of the least polluted cities in the world were ranked based on their 2021 average PM2.5 pollution levels.
As part of Smart Air’s open data pledge, the raw PM2.5 AQI 2021 world pollution data used for the rankings of the world’s least polluted cities are openly available to download.
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