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.

Pakistan's province of Punjab set up a "smog war room" to tackle severe pollution, officials said, as poor air quality turned its capital of Lahore into the world's most polluted city and forced the closure of some educational institutions.