The World’s Most and Least Polluted Countries

Updated: Aug 22

Air pollution has become a global problem. And while many countries are far more polluted than others, there are some that are shining a light on what could be possible for the rest of the world. It's important to note that the world’s most polluted countries are not always those that are the most polluting. Some of the least polluted countries in the world are responsible for the detrimental air quality impact they're having on other places.




How to Measure the World’s Most Polluted Countries


In order to ascertain which are the most polluted countries in the world, the source has to be credible and backed by evidence. For this reason, we decided to use IQAir’s 2021 rich and detailed air quality data, which measures the annual average concentration of PM 2.5 in each country in micrograms divided by cubic metres (µg/m³). Taken from 8,000 data points, the results cover every country in the world as well as some island territories as well.


The results aren’t pleasing, which is to be expected when over 99% of people live in an area with unsafe air.




World’s Most Polluted Countries


It comes as no surprise to find Bangladesh is the world’s most polluted country with 76.9 µg/m³ (only slightly lower the 77.1 µg/m³ measurement of 2020 and 83.3 µg/m³ in 2019). It has led the table in both 2020 and 2019 and although their emissions have decreased, it's not a big enough drop to halt the climate crisis and ensure the health of its citizens. Rounding out the top five most polluted countries in the world are Chad, Pakistan, Tajikistan and India.


It is no surprise that poorer, larger countries are higher up the list than their richer counterparts. There simply isn’t the infrastructure to be quite so pioneering when it comes to air quality in these countries, while their large populations mean that there are more vehicles on the road (many of which are older models and emit more emissions than newer vehicles). Even so, if these countries can move to more eco-friendly energy sources and invest in public transport that emits fewer pollutants, the world’s pollution will quickly dissipate.


The top ten list of the world's most polluted countries as of 2021 is:

  1. Bangladesh – 76.9 µg/m³

  2. Chad – 75.9 µg/m³

  3. Pakistan – 66.8 µg/m³

  4. Tajikistan – 59.4 µg/m³

  5. India – 58.1 µg/m³

  6. Oman – 53.9 µg/m³

  7. Kyrgyzstan – 50.8 µg/m³

  8. Bahrain – 49.8 µg/m³

  9. Iraq – 49.7 µg/m³

  10. Nepal – 46 µg/m³


Many of the 2021 figures have increased compared to 2020 as a result of the travel and lockdown restrictions due to the pandemic. As these restrictions lifted, life returned to normal, which meant so did the pollution levels. Perhaps the most surprising entry from this latest data is that of Tajikistan, which measured 30.9µg/m³ in 2020 – a huge 28.5 µg/m³ increase compared to its 2021 level.


World’s Least Polluted Countries


The world’s least polluted countries are a mixture between countries and island countries, with the top three being Cape Verde, the Caribbean Netherlands (Bonaire, Sint Eustatius and Saba) and Finland. Despite having low levels of PM2.5, none of these countries are the least populated areas on Earth.


The world’s least polluted areas are all territories and, understandably, are all islands with relatively small populations. New Caledonia, the US Virgin Islands and Puerto Rico were all equal in 2020 with just 3.7 µg/m³, however all three territories air pollution level has increased – another downfall as a result of the pandemic.


The top ten list of the world's least polluted countries as of 2021 is:

  1. New Caledonia – 3.8 µg/m³

  2. US Virgin Islands – 4.5 µg/m³

  3. Puerto Rico – 4.8 µg/m³

  4. Cape Verde – 5.1 µg/m³

  5. Bonaire, Sint Eustatius and Saba – 5.1 µg/m³

  6. Finland – 5.5 µg/m³

  7. Grenada – 5.5 µg/m³

  8. Bahamas – 5.5 µg/m³

  9. Australia – 5.7 µg/m³

  10. Estonia – 5.9 µg/m³


World’s Least Polluted Countries with a Large Population


It does not seem fair to compare the likes of Bangladesh, Pakistan and India to tiny territories and comparatively small countries. Although it's possible to compare pollution rates per square kilometre, the data obviously has serious flaws due to a far smaller population size, meaning far fewer vehicles on the roads, and far less industries and factories upon which the world relies. So in the short term, what would be an achievable rate of pollution for these most polluted countries?


The best comparisons are China (32.6µg/m³), which has over 1 billion more people than Bangladesh, but has less than half the pollution and Indonesia, which has 111 million more people, but a pollution measurement of 34.3µg/m³.


How to quickly reduce pollution levels in the world’s most polluted countries


There is no silver bullet or easy fix for the world’s most polluted countries but there are solutions to lower pollution levels. The likes of Colombia and Indonesia enacted public transport programmes to reduce their emissions, while companies can turn to projects like U-Earth’s Pure Air Zone, an award-winning biotech solution that uses bacteria and enzymes taken from the natural world to capture and neutralise contaminants in the air.


If action isn't taken now, we'll likely see air pollution levels continue to rise each year. Now is the time to make a change. Book a meeting with one of our air quality specialists to see how you and your company can make a difference today or join our community below to stay up-to-date on the latest air quality news.


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