Delhi, Lahore smog forces school closures as residents choke

India's capital has shut schools and coal plants as it battles dangerous levels of air pollution in the region that on Wednesday left residents of Lahore choking on acrid smog.

Air quality has worsened across northern India and adjacent parts of Pakistan in recent years, as industrial pollutants, smoke from seasonal crop burn-off, and colder winter temperatures coalesce into toxic smog.

Delhi is consistently ranked the world's worst capital for air quality, with levels of pollutants last week reaching more than 30 times the maximum limit recommended by the World Health Organisation.

The city on Tuesday ordered the closure until the end of the month of six of 11 coal-fired power plants surrounding the metropolis in a bid to tackle the filthy air.

The move comes after India led the charge at the weekend to weaken anti-coal pledges at the UN COP26 climate summit, with critics saying it prioritised economic growth over the planet's future.

The Indian capital of 20 million people has also cancelled school classes and urged people to work from home while banning non-essential trucks from entering the city in an effort to clean the smog.

In an order passed late Tuesday, the city's Commission for Air Quality Management said all education institutions should remain shut until further notice.

“Anti-smog guns” — which spray mist into the air — and water sprinklers were ordered to operate at pollution hotspots at least three times a day.

The commission also said that at least half of government workers were being sent home and private firms should follow suit.