Delhi: World’s Most Polluted Capital

According to the 2024 World Air Quality Report release on 11th March 2025, Delhi recorded an average PM2.5 concentration of 91.8 μg/m³, maintaining its position as the world’s most polluted national capital for the sixth consecutive year.

Key Findings

India’s Air Pollution Ranking: India is the fifth most polluted country, with an average AQI of 50.6 μg/m³, which is 10 times higher than the WHO’s annual PM2.5 guideline of 5 μg/m³.
Most Polluted City in the World: Byrnihat (Assam-Meghalaya border) was the most polluted metropolitan area globally, with an annual PM2.5 concentration of 128.2 μg/m³.
Indian Cities in the Top 20: 13 out of the world’s 20 most polluted cities are in India, including Faridabad, Loni (Ghaziabad), Gurgaon, Greater Noida, Bhiwadi, Noida, Muzaffarnagar, and Delhi (including Central Delhi).
Health Impact: Air pollution in India is reducing life expectancy by an estimated 5.2 years, highlighting the severe public health burden.
Air Pollution in the US: Los Angeles was the most polluted major city in the US, while Ontario, California ranked as the most polluted city overall.
Marginal Improvement in India: India saw a 7% decline in PM2.5 levels, dropping from 54.4 µg/m³ in 2023 to 50.6 µg/m³ in 2024, but six of the world’s ten most polluted cities remain in India.