The report, released Wednesday, notes New Delhi's air is worse than that of Beijing, which has a reputation for pollution, and adds 13 of the world's 20 most polluted cities in the world are in India. New Delhi, Patna, Gwalior and Raipur are in the top four positions in the rating of 1,600 cities in 91 countries.
Anumita Roy Chowdhary, head of India's Department of Air pollution, Center for Science and environment, commented that the report "comes as a shocking reminder on how things are getting worse. We need a very strong policy response on this."
The Indo Asian News Service said the country's political leadership has not regarded public health as a high priority, despite complaints from residents in urban areas.
There is little awareness of air pollution danger in India, said Sumit Sharma of the Energy and Resources Institute in New Delhi.
"As a result of this, the government has also not taken any interest. Such an issue will be taken up by political parties only when people feel affected," Sharma said.
The WHO report estimated that in 2012, air pollution was responsible for the deaths of 3.7 million people, worldwide, under the age of 60.