Most polluted capital cities – ranked

The world’s most polluted capital cities have been ranked, revealing alarming levels of harmful particles in our urban areas

Delhi in India is the most polluted capital city in the world, according to the latest World Air Quality Report from IQAir, a Swiss air‐quality technology company.

At the other end of the scale, Nassau in the Bahamas is the world’s least polluted capital city. The Bahamas is also the country with the cleanest air in the world overall.

The annual global assessment uses empirically measured ground‐level PM2.5 data – from over 40,000 monitoring stations across 8,954 locations in 138 countries, territories, and regions – to analyse annual air quality exposure at city, country and regional levels.

The report includes extensive city and national rankings, regional summaries and a global map. It paints a sobering picture: air pollution remains a global challenge, with only a handful of countries meeting WHO guidelines.

Yet incremental progress is occurring – cities adhering to thresholds have nearly doubled year-over-year. By combining robust measurement practices with broad geographic data, the report provides a vital resource in the fight for cleaner air.

Air Quality Index

The report analyses results from over 40,000 monitoring stations around the world, making it the world’s largest centralised platform for measuring air quality.

It also draws on data collected from thousands of…