Dhaka, Jan. 28 -- Dhaka, the densely populated capital of Bangladesh, ranked first among the world's most polluted cities on Wednesday morning, recording an Air Quality Index (AQI) of 305 at 8:13 am.

Today, the city's air was classified as 'very unhealthy', indicating a serious health threat, according to the AQI report.

Cairo in Egypt, Kolkata in India and Ulaanbaatar in Mongolia occupied the second, third and fourth position on the list, with AQI scores of 267, 226, and 214 respectively.

According to the AQI scale, a reading between 50 and 100 is considered 'moderate', with generally acceptable air quality, though sensitive individuals should limit prolonged outdoor exertion. AQI levels of 101-150 are 'unhealthy for sensitive groups'...