The World Air Quality Report 2024, released by Swiss firm IQAir, has named Byrnihat, a small industrial town in Assam, as the world’s most polluted city, with a PM2.5 concentration of 128.2 micrograms per cubic meter—over 25 times the World Health Organization’s (WHO) safe limit of 5 micrograms.

Delhi retains its grim title as the most polluted capital globally for the sixth year running, registering 91.6 micrograms per cubic meter. India dominates the global pollution rankings, with 13 of the top 20 most polluted cities, including Mullanpur, Faridabad, Loni, Gurugram, Ganganagar, Greater Noida, Bhiwadi, Muzaffarnagar, Hanumangarh, Noida, and New Delhi, alongside Byrnihat and Delhi.

The report, analyzing data from over 40,000 monitoring stations across 138 countries, reveals that 91.3% of these regions exceed WHO guidelines. India ranks fifth among the world’s most polluted nations in 2024, down from third in 2023, with a national PM2.5 average of 50.6 micrograms per cubic meter—a 7% improvement from 54.4 micrograms in 2023. Despite this, six of the top 10 most polluted cities globally are Indian, highlighting the country’s ongoing air quality crisis.

Byrnihat’s extreme pollution is driven by emissions from its 41 factories—iron, steel, and cement plants—combined with heavy truck traffic as a transit hub near Meghalaya. Delhi’s persistent haze results from vehicular exhaust, industrial output, and seasonal stubble burning.

The report estimates that air pollution slashes Indian life expectancy by 5.2 years. Globally, only seven countries met WHO standards in 2024, with India absent from that list. While India shows slight progress, the concentration of polluted cities underscores the urgent need for stronger environmental measures to combat this public health emergency.