Whatever the causes of the smog, by one ranking Delhi was not just the most polluted city in the world, but “nearly five times as bad as the second most polluted city, Dhaka,” in Bangladesh next door, as Shashi Tharoor, a leader of the opposition in Parliament and best-selling author, posted on X.

India's capital city of Delhi has virtually shut down as air pollution hit "severe plus" levels, according to Indian government officials in its pollution control authority.

Around 38% of the pollution in New Delhi this year has been caused by stubble burning - a practice where stubble left after harvesting rice is burnt to clear fields - in the neighbouring states of Punjab and Haryana, according to SAFAR, a weather forecasting agency under the ministry of earth sciences.

Air pollution chokes New Delhi every winter, but this year's smog has already derailed everything from transport and road work to schools.

Delhi's new action plan to combat rising pollution includes a ban on non-essential trucks, school closures, and remote work.