"Looking at the predicted air wind and air quality index we are closing all higher secondary schools," said Marriyum Aurangzeb, a senior minister in Punjab during a press conference in Lahore.

The decision will affect millions of children in cities that are among the largest of Pakistan, including the Punjab's provincial capital Lahore.

For days, some of provinces cities have been enveloped by smog, a mix of fog and pollutants caused by low-grade diesel fumes, smoke from seasonal agricultural burning and winter cooling.

The minister said on Wednesday the air quality index (AQI), which measures a range of pollutants, spiked above 1,000 -- well above the level of 300 considered 'dangerous' - according to data from IQAir.

"This morning's AQI crossed 1,100," Aurangzeb said.

"I appeal citizens, that for god's sake don't come out of your houses," she said adding that wearing a face mask was made mandatory in affected cities.

She also announced that half of the staff in public and private offices will work remotely.