For the sixth consecutive year, Delhi has been named the world’s most polluted national capital, according to the World Air Quality Report by Swiss monitoring company IQAir. The report also reveals that 13 of the world’s 20 most polluted cities are in India, with Byrnihat in Meghalaya ranking as the most polluted city globally.

The grim report, which analysed data from 40,000 air quality monitoring stations across 138 countries, found that the most polluted city in the world is Byrnihat, a small industrial town on the Assam-Meghalaya border. Byrnihat recorded an annual average PM2.5 concentration of 128.2 micrograms per cubic metre (µg/m3), far exceeding the World Health Organisation’s (WHO) recommended limit of 5 µg/m3.

Despite a slight improvement from 2023, India continues to be one of the world’s most polluted countries, ranking fifth globally with an annual average PM2.5 concentration of 50.6 µg/m3. The four most polluted countries were Chad, Bangladesh, Pakistan and Congo. PM2.5 pollution, which originates from sources like fossil fuel combustion, industrial emissions, and crop burning, is known to cause severe health issues, including respiratory diseases, heart attacks, strokes and even chronic kidney disease.

Delhi, the most polluted capital, recorded an annual PM2.5 level of 91.6 µg/m3 in 2024, only marginally lower than 92.7 µg/m3 in 2023. While the city’s pollution levels remain alarmingly high, the broader northern belt of India has witnessed particularly hazardous air quality episodes. The report highlighted that January saw extremely poor air quality in Delhi and Himachal Pradesh, while November brought severe pollution across Punjab, Chandigarh, Haryana and Himachal Pradesh.