Authorities in India’s smog-ridden capital have extended an emergency schools closure by a week, with no signs of improvement in the megacity’s choking levels of pollution.

New Delhi is blanketed in acrid smog every autumn, primarily blamed on stubble burning by farmers in the neighbouring agrarian states.

The city of nearly 30 million residents is regularly ranked as one of the most polluted on the planet, with its annual smog blamed for hundreds of thousands of premature deaths each year.

“As pollution levels continue to remain high, primary schools in Delhi will stay closed till 10th November,” Delhi state’s education minister Atishi posted on X, formerly Twitter.

Secondary schools “are being given the option of shifting to online classes”, added Atishi, who uses only one name, after days of high pollution levels.

Delhi state annually imposes restrictions on construction activities and orders some vehicles off roads when pollution reaches severe levels.

New Delhi is set to host a cricket World Cup match on Monday between Sri Lanka and Bangladesh. But both teams cancelled their scheduled pre-match training sessions in recent days over health risks from the smog.

Severe smog levels are expected to persist in the city for several more weeks.

Levels of the most dangerous PM2.5 particles – so tiny they can enter the bloodstream – reached 570 micrograms per cubic metre on Sunday, according to IQAir, nearly 40 times the daily maximum recommended by the World Health Organization.

A Lancet study in 2020 attributed 1.67 million deaths to air pollution in India during the previous year, including almost 17,500 in New Delhi.