According to a new study showing South-Asia's battle with deteriorating air quality and the global climate accord, India accounts for having seven of the top 10 of the most polluted cities in the world.
Delhi had an average yearly PM2.5 concentration at 113.5 micrograms per cubic metre, followed by Dhaka at 97.1 micrograms per cubic metre.
According to the report, air pollution will cause around 7 million premature deaths globally next year and have a major economic impact.
He noted that burning fossil fuels is both the key driver of climate change and of air pollution worldwide, and that shifting atmospheric conditions have worsened air quality and amplified forest fires.
PM2.5 is particulate matter that has a diameter of less than 2.5 micrometers, which is about three percent the diameter of a human hair.
"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.
Gurugram in 2018 too had topped the list in pollution levels.
But critics have accused his administration of failing to adequately address environmental issues, including air pollution, and criticised New Delhi's recently-minted National Clean Air Programme (NCAP) as insufficient. 22 of the top 30 are in India.
"The report is a reminder to us indicating that our efforts and actions to reduce the invisible killer, i.e., air pollution, are not enough and we need to do much more than already planned and done", said Pujarini Sen of Greenpeace India. However, the number of Chinese cities with high pollution is still substantial. The overall score of Gurugram improved relatively from that of a year ago, however, the number of hazardous matters in its atmosphere is more than thirteen times the World Health Organization annual standard. IQAir AirVisual has included data from air quality monitors operated by private organisations and individuals.