India is home to 21 of the 30 world's most-polluted cities, as per the 2019 World Air Quality Report. Ghaziabad in Uttar Pradesh is the most polluted city. It had an average PM 2.5 levels of 110.2 in 2019. This is followed by Hotan in China (2) and Gujranwala in Pakistan (3).
Next comes Faisalabad in Pakistan (4), Delhi (5), Noida (6), Gurugram (7), Raiwind in Pakistan (8), Greater Noida (9) and Bandhwari (10). Bangladesh is the most polluted country in the world. Majority of the polluted countries or regions are located in the South Asia region.
Reasons for high air pollution levels are sandstorms, wildfires and rapid urbanisation. India's air pollution levels dipped by 20 percent from 2018 to 2019. This after, National Clean Air Programme (NCAP) was launched last year.