While all regions of the world are affected, populations in low-income cities are the most impacted.
Four of the five cities in the world with the worst air pollution are in India, the World Health Organization said on Thursday.
Zabol in Iran is the most polluted city in the world. New Delhi, which was worst polluted city has improved its position to ninth rank.
More than 80 per cent of people living in urban areas that monitor air pollution are exposed to air quality levels that exceed WHO limits, according to the report.
While all regions of the world are affected, populations in low-income cities are the most impacted.
The four worst affected cities in India are: Gwalior, Allahabad, Patna and Raipur.
According to the latest urban air quality database, 98 per cent of cities in low- and middle income countries with more than 100 000 inhabitants do not meet WHO air quality guidelines.
However, in high-income countries, that percentage decreases to 56 per cent.
Photograph: Reuters
