Pakistan's Punjab declared a health emergency due to toxic smog on Friday, banning construction, shutting schools for another week and moving universities online, with a three-day lockdown possible, the province's senior minister said on Friday.

Air quality in Lahore reached hazardous levels this week, while other cities in South Asia also battle toxic pollution.

One doctor compared breathing in Pakistan's toxic air to smoking "dozens of cigarettes a day" as Lahore is the world's most polluted city this week.

With smog intensity escalating in Lahore at the end of October, affecting its 13 million residents, the Punjab government imposed a “green lockdown” and set up a “smog war room.”

The government of Pakistan’s most polluted province has launched a new policy to address a protracted smog crisis, after the world’s worst air shuttered schools and saw 900 people seek hospital treatment in a single day.

Cities across India and Pakistan are struggling with dense smog that has worsened air quality, with authorities declaring a "health crisis" in the latter's Punjab province.

Pakistan's Punjab province declared a health emergency due to toxic smog on Friday, banning construction, shutting schools for another week and moving universities online, while hundreds of thousands of Muslims prayed for rain and forgiveness.

From banning tuk-tuks and barbecues to demolishing old brick kilns, Pakistan's government is pushing a series of measures to fight record-breaking smog.