Air quality standards: Delhi still most-polluted capital in world in 2021

Delhi was found to be the most polluted capital in the world for the fourth consecutive year in 2021, according to a new report.

In 2021, none of the cities in India met the prescribed World Health Organization air quality standards of 5 micrograms per cubic meter (µg/m3), stated the World Air Quality Report 2021, prepared by Swiss firm IQAir and released globally on Tuesday.

The report, presenting an overview of the state of global air quality in 2021, is based on PM2.5 air quality data from 6,475 cities across 117 countries.