According to the official Air Quality Index (AQI), Lahore had a score of 243 while international monitoring bodies placed it at 397.
Karachi stood fifth in the list of most polluted cities in the world with an AQI of 173.
At 175 AQI (Particulate Matter (PM) 2.5), Mongolian city Ulaanbaatar stood at the second position, Indian city Kolkata third and Delhi at the fourth position respectively in the list of most polluted cities in the world.
PM 2.5 concentration in Lahore air is currently 38.6 times above the WHO annual air quality guideline, reports the Swiss AQI Monitor.
According to AQI air quality index, a pollution concentration score above 301 is considered hazardous to health.