Dhaka, Oct. 11 -- Dhaka ranked 6th among the world's most polluted cities on Sunday morning, recording an Air Quality Index (AQI) score of 166 at 08:31am.

The air quality was classified as 'unhealthy', meaning the concentration of pollutants in the air has reached a level that could pose health risks to the general population, according to the AQI scale.

Kolkata in India ranked first with an AQI score of 187, while Singapore ranked second with a score of 184, followed by Hanoi in Vietnam in the third place with an AQI score of 178.

According to AQI standards, a reading between 101 and 150 is considered 'unhealthy for sensitive groups', while 151 to 200 is classified as 'unhealthy'. A reading between 201 and 300 is considered 'very unhe...