NEW DELHI: New Delhi was the world’s most polluted capital city in 2018, two groups monitoring air pollution said on Tuesday in a study of the amount of fine particulate matter known as PM2.5 in 61 capital cities around the world.

The Indian capital, home to more than 20 million people, was followed by the Bangladesh capital of Dhaka and Kabul, capital of Afghanistan, 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 metre 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 micrometers or less in diameter, is so dangerous because it lodges deep in the lungs.

The World Health Organisation sets a daily mean air quality guideline of 25 micrograms of PM2.5 per cubic metre 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.

“In mainland China, in particular, this has led to significant improvements in year-on-year reductions in PM2.5 levels,” the groups said in their joint study.

Published in Dawn, March 6th, 2019