, April 8 -- Dhaka, the densely populated capital of Bangladesh, ranked fourth among the world's most polluted cities on Wednesday morning, recording an Air Quality Index (AQI) of 151 at 11:58 am.

The air quality was classified as 'unhealthy', indicating potential health risks for the general population, according to the AQI scale.

Chiang Mai in Thailand,Hanoi in Vietnam and Kathmandu in Nepal occupied the top three positions on the list, with AQI scores of 175, 165 and 160 respectively.

According to AQI standards, a reading between 101 and 150 is considered 'unhealthy for sensitive groups', 151 to 200 'unhealthy', 201 to 300 'very unhealthy', while levels above 301 are deemed 'hazardous', posing serious health risks.

The AQI, which r...