Every year, a global report analyzes the air quality of thousands of major cities and reveals which places are the most polluted… but also those where the air is the purest. Where is the least polluted city in the world?
Breathing healthy air has become a real luxury in many regions of the world. The World Health Organization (WHO) also points out that almost the entire world population is exposed to pollution levels higher than its recommendations. The annual World Air Quality Report 2025 published by the monitoring platform IQAir analyzes the pollution levels of thousands of cities around the world, to establish a ranking of the most and least polluted areas in 2025. But which city is the best air quality, which is an essential criterion for the well-being of residents ?
Unsurprisingly, very densely populated cities are found at the top of the rankings of the most polluted cities, particularly in South Asia and Africa, such as Loni, India, named as the most polluted city in the world, followed by Hotan in China, Byrnihat and Delhi, both also located in India, then Faisalabad in Pakistan.
Conversely, some cities are doing well and display relatively low (or less alarming) levels of pollution. Every day, the IQAir platform publishes a ranking to designate the least polluted large cities of the moment. And the results are sometimes surprising!
For example, on May 25, 2026, it was San Francisco in the United States which appeared at the top of this daily ranking, followed by Warsaw and Krakow in Poland, Stockholm in Sweden and Moscow in Russia. However, Paris is unfortunately often relegated to the bottom of this ranking and was, for example, in 96th place on May 25.
But the city that was designated as the least polluted in the world in 2025 by the World Air Quality Report 2025 is Nieuwoudtville. Located in South Africa, this small town of several thousand inhabitants has extremely low levels of fine particulate matter, that is, microscopic particles of pollution, which are so small that they can penetrate deep into the lungs and even pass into the blood.
It must be said that the region is not very urbanized and that the small town benefits from a preserved natural environment and a very small population. The quality of its air is therefore exceptional. In 2nd place on this podium, we also find the island of Utö in Finland, then Līhuʻe in Hawaii.
