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.

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.”

A Pakistani province declared a health emergency Friday due to smog and imposed a shutdown in two major cities. Smog has choked Punjab for weeks, sickening nearly 2 million people and shrouding vast swathes of the province in a toxic haze.

The absence of a top provincial politician at the time the country is battling an air emergency involving toxic smog has sparked a debate in Pakistan. Authorities in Punjab province announced a health emergency and said they are mulling a three-day lockdown as the air crisis ahead of winter has trapped dust,