The 2025 IQAir World Air Quality Report describes the air we breathe as a “fragile asset.” While the world has finally recognized air pollution as a top-tier global risk, environmental factors like wildfires, made more frequent and intense by climate change, make it harder to keep the air clean.
According to the United Nations General Assembly, air pollution is now officially recognized as a major cause of non-communicable diseases like heart disease, stroke, and cancer. Children are particularly vulnerable as respiratory issues developed during childhood are often irreversible.
Worryingly, the IQAir World Air Quality Report 2025 shows that the situation is only getting worse. In 2025, only 13 countries and territories managed to meet the World Health Organization (WHO) annual guideline of 5 µg/m³, and only 14% of cities worldwide — a 17% decrease compared to the previous year.
The IQAir World Air Quality Report 2025 covers 9,446 cities across 143 countries, regions, and territories. The information is sourced from more than 40,000 monitoring stations worldwide and managed by a lot of contributors, ranging from government agencies and universities to engaged citizen scientists.
The worst cases of 2025
Central and South Asia remain the most polluted regions on Earth, with 17 of the 20 most polluted cities in the world located there. To illustrate the scale of the problem in Asia, the world’s 25 most polluted cities were all located in India, Pakistan, and China, with India being home to three of the four most polluted cities on the planet.
Overall, the five most polluted countries are Pakistan (67.3 µg/m³), Bangladesh (66.1 µg/m³), Tajikistan (57.3 µg/m³), Chad (53.6 µg/m³), and D.R. Congo (50.2 µg/m³).
In India, which ranked 6th, the city of Loni is the country’s and world’s most polluted city, with an annual average of 112.5 µg/m³, which is a nearly 23% increase from 2024 and more than 22 times the WHO guideline. New Delhi also saw intense public protests in November 2025 as air quality reached hazardous levels, with protesters holding signs like “I miss breathing.”
The wildfires effect
Even regions that usually have clean air struggled in 2025 due to massive wildfires. Canada and Europe saw record emissions from biomass burning, releasing about 1,380 megatonnes of carbon into the atmosphere.
In North America, Canada’s national average increased by 10%. Flin Flon, Manitoba, became the region’s most polluted city after fires in May caused PM2.5 levels to skyrocket to eight times what they were the previous year.
The best cases of 2025
Nieuwoudtville, South Africa, officially received the title of the world’s cleanest city in 2025, maintaining an incredibly low annual average PM2.5 concentration of just 1.0 µg/m³. On a broader scale, French Polynesia took the top spot among the countries with the cleanest air, with an average of 1.8 µg/m³. It was followed by Puerto Rico (2.4 µg/m³) and the U.S. Virgin Islands (2.5 µg/m³).
In Europe, Iceland (3.7 µg/m³), Andorra (4.3 µg/m³), and Estonia (4.9 µg/m³) successfully met the WHO air quality standards. They were closely followed by Finland (5.2 µg/m³) and Sweden (5.5 µg/m³), which both remained very close to the 5 µg/m³ health target.
In Latin America and the Caribbean, the overall trend was very positive. 208 cities saw their pollution levels drop in 2025, while only 95 saw an increase. The change was a very important win for the region, largely thanks to the end of the El Niño drought, which brought more rain and wind to clear the air in places like Honduras and Guatemala. Honduras was the region’s biggest success story, cutting its average pollution by 59% in just one year, falling from 15.2 µg/m³ to 6.3 µg/m³.
Oceania also remained one of the world’s cleanest regions, with 61% of cities meeting the WHO guideline.
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The U.S.
While overall air quality in the U.S. remained relatively good, there were some major differences between cities. El Paso, Texas, was the most polluted major U.S. city in 2025, largely due to a 46% spike in pollution caused by historic dust storms. On a regional level, Southeast Los Angeles, specifically areas like Cudahy and East Los Angeles, was identified as the most polluted region in the country. On the other hand, Seattle, Washington, was the cleanest major U.S. city, consistently meeting the WHO’s strict health guidelines with an average below 5 µg/m³.
Editor’s Note: The opinions expressed here by the authors are their own, not those of impakter.com — In the Cover Photo: A person walking in Delhi, India. Cover Photo Credit: saikat ghosh
