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 government on Friday declared smog a “health crisis" and used artificial rain in several cities across the province in an effort to combat its hazardous levels, as millions reported breathing problems and other respiratory issues over the past month.

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.