The IQAir AirVisual 2018 World Air Quality Report was compiled by Greenpeace in association with IQAir AirVisual. The index measures the presence of fine particulate matter PM2.5 in the air.

• Seven of the top 10 most polluted cities in the world are in India. Gurugram led all cities in pollution levels in 2018, even as its score improved from the previous year.
• The five most polluted cities in the world are Gurugram, Ghaziabad, Faridabad, Bhiwadi (India) and Faisalabad (Pakistan).

The report adds that fine particulate matter comes from fuel combustion, both from mobile sources such as vehicles and from stationary sources such as power plants, industry, households, agriculture or biomass burning.