Karachi again topped the list of the most polluted cities of the world on global Air Quality Index on Friday. The city’s air quality index was 177 at 11 am that put it in the hazardous category with regard to PM particulate matter level.
AQI as high as 151-200 is considered unhealthy, while an AQI between 201 to 300 is more harmful and an Air Quality Index over 300 is dubbed extremely hazardous. Yesterday, Punjab’s provincial capital Lahore topped the list of the most polluted cities in Pakistan.
According to experts, the air becomes heavier in the winter as compared to summer, causing poisonous particles in the atmosphere to move downwards and making the atmosphere polluted. As a result, a layer of polluted particles, including large amounts of carbon and smoke, covers a city.