Pakistan's smog-hit Lahore will close schools for two days a week to protect children's health, with the city on Wednesday clocking in as the world's most polluted according to a global air quality index.

Hospitals have warned of an influx of patients suffering from breathing problems as well as eye and throat irritation as a result of the grey blanket of smog that engulfs the city.

Air quality in the city of more than 11 million is consistently among the world's worst, and on Wednesday its pollutant levels topped a regularly updated global index run by the Swiss monitoring platform IQAir.

Pollution on Wednesday hit a level of more than 230 on IQAir's scale -– approaching the hazardous level of 300 set by the monitor. Last week Lahore recorded a level of 504, its highest this year.

The Lahore High Court on Tuesday ruled that schools must close on Fridays and Saturdays, as well as the usual Sunday break, until further notice.

A separate ruling on Wednesday said all public sector staff must work from home on Fridays and Saturdays.

The head of the province's teachers' association warned cutting school days was "not a viable solution".

"Staying at home is not necessarily going to protect students from the smog any more than coming to school. At least by coming to school the students will not be affected academically," Rana Liaqat Ali, the secretary general of the Punjab Teachers Union, told AFP.

"Smog, Covid-19, and dengue are all now part of our daily reality. We need to learn to live with them and not isolate ourselves."

Despite court orders over the years instructing officials to come down hard on those responsible for the emissions, Pakistan's authorities are ill-equipped to deal with the mammoth problem.

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

Delhi is consistently ranked as the world's worst capital for air quality, sometimes reaching more than 30 times the maximum limit recommended by the World Health Organization.