Air pollution levels in Delhi are considered seriously only when winter descends on the city. Every December and January, images of the capital smothered in smog go viral with reports citing the fallout.

Statistics, however, point to a larger, more alarming phenomenon. Half of the air pollution-related deaths in the world in 2015 took place in India and China – each of them reported 1.1 million deaths.

If that was the case two years ago, the problem is bigger today, with the number of deaths rising to 1.2 million.

New Delhi tops the list of India’s most polluted cities, according to a study by Greenpeace India.

Of the 20 most polluted cities listed by the World Health Organisation, 11 are in Punjab, Uttarakhand and Uttar Pradesh. Significantly, the election campaigns in these states had no mention of the bad air quality.

But Union Environment Minister Anil Madhav Dave has refused to accept that air pollution is the reason unless the data and causes are validated by Indian institutions.