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 U.N. children’s agency is warning that the health of 11 million children in Pakistan’s eastern Punjab province is in danger because of air pollution that experts say has become a fifth season in recent years.

A Pakistani province declared a health emergency on November 15 due to smog and imposed a shutdown in two major cities.

Punjab province in Pakistan has declared a health emergency and closed two cities due to severe smog affecting nearly 2 million people.

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.

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.

LAHORE, Pakistan A Pakistani province declared a health emergency Friday due to smog and imposed a shutdown in two major cities.Smog has choked Punja..

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