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.

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.

Pakistan's most populated province of Punjab on Friday extended school closures in smog-hit major cities by a week, as the country battles record

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.

The authorities have also imposed a "health emergency" in Lahore and Multan districts to combat dense smog blanketing the province of about 130 million population for the last few weeks

According to the provincial health department, around two million cases of respiratory disease, besides complaints of asthma, chest infections, conjunctivitis and heart issues, have been reported in hospitals during the last month.