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. 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 of 25 micrograms of PM2.5 per cubic meter of air. India is home to 15 of the 20 most polluted cities in the world, they said.

Source: The Express Tribune March 05, 2019 15:00 UTC