The Indian capital, followed by Dhaka and Kabul, according to the study by IQ AirVisual. A Swiss-based group that gathers air-quality data globally, and Greenpeace.
New Delhi’s toxic air is caused by vehicle and industrial emissions, dust from building sites, smoke from the burning of rubbish and crop residue in nearby fields.
The city’s average annual concentration of PM2.5 in a cubic meter of air was 113.5 in 2018, the groups said in their report. More than double the level of Beijing, which averaged 50.9 during the year, making it the eighth most polluted in the world.

PM2.5, or particles of 2.5 micrometres or less in diameter, is so dangerous because it lodges deep in the lungs. The World Health Organization sets a daily mean air quality guideline. That is 25 micrograms of PM2.5 per cubic meter of air.
China struggled for years to enforce environment rules and crack down on polluting industries. But it has benefited in recent years from vastly improved legislation and greater political will to combat poor air quality. India is home to 15 of the 20 most polluted cities in the world, they said.