Out of the top 20 most polluted cities in the world, 11 are in India! This information was revealed in a 2024 air quality report by a Sweden-based organization called ‘IQAir’.

At the top of the list is Birnihat (Air Quality Index or AQI 128.2), located on the Assam-Meghalaya border. This northeastern Indian city narrowly beat the capital, Delhi, to claim the first spot.

The remaining 10 Indian cities in the top 20 are, in order, Delhi, Mullanpur, Faridabad, Lonii, Noida, Gurugram, Ganganagar, Greater Noida, Bhiwadi, and Muzaffarnagar. Kolkata ranks at number 183 with an annual average AQI of 45.6.

According to the Swiss organization’s report, Delhi is the world’s most polluted capital city. Meanwhile, in 2024, India ranked as the fifth most polluted country in the world, down from third place in 2023. The report further states that in 2024, the average concentration of PM 2.5 in India was 50.6 micrograms per cubic meter, which is many times higher than the World Health Organization (WHO) air quality guidelines. According to WHO standards, almost no Indian city has satisfactory air quality. However, the report mentions that compared to 2023, the level of airborne pollutants in India has decreased by seven percent. Despite this, pollution levels remain largely unchanged. Delhi continues to maintain high pollution levels, with an annual average PM 2.5 concentration of 91.6 micrograms per cubic meter.

The report highlights that in 35 percent of Indian cities, the annual average concentration of PM 2.5 is 10 times higher than WHO’s safe limit. Among these, the situation is worst in northern India. Apart from Kolkata in West Bengal, six other cities are on the Swiss organization’s list: Durgapur, Asansol, Barakpur, Howrah, Siliguri, and Haldia.

Notably, according to WHO air quality standards, the acceptable level of pollution should be 5 micrograms per cubic meter. PM 2.5 refers to fine particulate matter smaller than 2.5 microns, which can penetrate deep into the lungs and even enter the bloodstream. Experts warn that exposure to PM 2.5 can cause respiratory issues, heart disease, and even cancer. Sources of PM 2.5 include emissions from vehicles and industrial areas, construction activities, burning wood, or crop stubble.