Dhaka, March 24 -- Dhaka, the densely populated capital of Bangladesh, ranked fourth among the world's most polluted cities on Tuesday morning, recording an Air Quality Index (AQI) of 155 at 9:56 am.

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

Delhi in India, Beijing in China, and Busan in South Korea occupied the first, second, and third spots on the list, with AQI scores of 205, 180, and 163 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', 151-200 ...