The atmosphere in Karachi and Lahore has been declared unhealthy for human health.
According to the Air Quality Index, Lahore is the first and Karachi the third most polluted city in the world.
On the other hand, Dhaka is the second most polluted city in the world. According to the classification, 151 to 200 degree pollution is harmful to health while 201 to 300 degree pollution is extremely harmful to health.
It should be noted that more than 301 levels indicate dangerous pollution.