NEW DELHI: Air pollution is the fifth largest killer in India taking 6.2 lakh lives per year and Delhi is among one of the five most critically polluted regions in the country, a study by a US-based health institute has claimed.

The other four most critically polluted regions in the country are Ghaziabad, Gwalior, West Singbhum district in Jharkhand and Raipur, according to the study.