Lahore is the second-most polluted city, with an average Air Quality Index (AQI) of 395 on Monday morning.
Karachi is the world's third-most polluted city, whereas New Delhi, the Indian capital, is at the top of the list.
Health experts have encouraged individuals to avoid unnecessary travel and to use a face mask while going outside.
The inhabitants of Lahore are having difficulty breathing owing to haze and air pollution.
The interim provincial government had ordered the use of face masks mandatory in smog-stricken regions of Punjab the day before. The face mask was made mandatory for one week.
The face mask was declared mandatory in the districts of Lahore, Nankana Sahib, Sheikhupura, Kasur, Gujranwala, Gujrat, Sialkot, Narowal, Hafizabad, and Mandi Bahauddin.
According to the World Health Organisation, air pollution kills 4.2 million people worldwide each year.
An AQI level of 400–500 has an influence on healthy individuals and is harmful to those who already have ailments, whereas a level of 150–200 causes discomfort in persons who have asthma, lung, or heart issues. Levels ranging from 0 to 50 are deemed satisfactory.