Karachi, the largest city in Pakistan, has been ranked as the most polluted city in the world on the Air Quality Index (AQI). The average AQI reading for Karachi was 220, while Lahore ranked third on the list.
To understand how bad this pollution is, it’s important to know that an AQI of 151-200 is considered unhealthy, 201-300 is even more harmful, and anything over 300 is extremely hazardous.
The AQI is calculated by considering five types of pollution: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
