Delhi continued to be the most polluted capital city in the world for the fourth consecutive year in 2021, with a 14.6% increase in PM2.5 concentrations, according to a new report that analyzed real-time air quality data.

To make matters worse, the report stated that 63 of the 100 cities with the worst air quality were in India.

None of the cities in India met the prescribed World Health Organization air quality standards of 5 micrograms per cubic meter (as of September 2021), with Delhi and Mumbai registering more than 10 times the ‘healthy’ benchmark.

‘India also continues to feature prominently among the most polluted cities with 35 of the top 50 most polluted cities being in this country. India’s annual average PM2.5 levels reached 58.1 μg/m3 in 2021, ending a three-year trend of improving air quality,’ the report said.

Dhaka ranked second after Delhi, among the world’s most polluted capitals, followed by N’Djamena in Chad, Dushanbe in Tajikistan and Muscat in Oman. The air in Bangladesh in general was declared the world’s most polluted in 2021, with PM2.5 concentrations of 76.9 micrograms per cubic meter.

It must be noted that on the global front, the report finds that only three per cent of cities and no single country met the latest WHO’s PM2.5 annual air quality guidelines. 

While Central and South Asia had some of the world’s worst air quality, with 46 of the world’s 50 most polluted cities, the cleanest air was found in the South Pacific island nation of New Caledonia (3.8).

Finland had the lowest PM2.5 concentrations among developed nations (5.5), the report added.

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