A recent list shared by the World Health Organization about the 20 most polluted cities of the world shows that 13 of those cities are from India.
The report rated about 1600 cities from 91 countries for the quality of their air. They were measured for the harmful pollutants which stick to the lungs and cause various diseases.
From the top 20 list Delhi, the capital of India, is ranked number 1, Patna at number 2, Gwalior at 3, Raipur at 4, Ahmadabad at 9, Lucknow at 10, Firozabad at 11, Khanpur at 13, Amritsar at 14, Ludhiana at 15, Allahabad at 18, Agra at 19, while Khanna was on 20th position.
This list includes three major cities of Pakistan Karachi, Peshawar and Rawalpindi as well in the beginning of the list at numbers 5, 6, and 7.