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.

In several areas of the city, pollution levels were more than 50 times higher than the World Health Organization’s recommended safe limit. Forecasts say the poor air quality will continue into the week.

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.

Delhi recorded air pollution more than 17 times above an acceptable level as worsening smog triggered curbs on trucking and shuttered construction sites and schools.

Air quality in northern India has worsened over the past week, with New Delhi's AQI recording a reading of 465, classified as "severe plus category", on Sunday evening due to unfavourable meteorological conditions,

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