Delhi Remains World’s Most Polluted Capital for Eighth Consecutive Year, Global Air Quality Report Shows

Delhi Remains World’s Most Polluted Capital for Eighth Consecutive Year, Global Air Quality Report Shows
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New data from the 2025 World Air Quality Report published by Swiss air‑quality monitoring organization IQAir shows that only 14 % of the nearly 9,500 cities worldwide met the World Health Organization’s (WHO) recommended air quality guideline in 2025.

According to the report, New Delhi, the capital of India, was ranked as the most polluted capital city globally for the eighth year in a row, with an annual average concentration of fine particulate matter (PM2.5) of 82.2 micrograms per cubic metre — far above the WHO guideline of 5 µg/m³.

Only a small number of countries and regions complied with international safety standards: just 13 countries/territories managed to keep annual PM2.5 levels at or below the WHO guideline, including French Polynesia, Puerto Rico and Barbados.

The report also identified several other cities with some of the worst air quality in 2025. After New Delhi, Dhaka (Bangladesh), Dushanbe (Tajikistan) and N’Djamena (Chad) were among the cities with the highest average PM2.5 levels.

In contrast, several capitals were noted for comparatively cleaner air. Papeete (French Polynesia), San Juan (Puerto Rico) and Bridgetown (Barbados) were cited among the least polluted capital cities in the report.