Calls for action mount as six Indian cities hit top 10 of air pollution

World Health Organisation report says high pollution puts millions of people in cities including Delhi at risk of early death

Environmental campaigners in India have called for the government to implement a "stringent, time-bound" plan to curb air pollution in cities, as a new World Health Organisation report suggests that six of the 10 most polluted cities in the world are in India.

The report, which contains data from 795 cities in 67 countries between 2008 and 2013, shows Indian cities have some of the highest concentrations of particulate pollution, which can cause fatal damage to the heart and lungs.