, March 5 -- Dhaka, Bangladesh's densely populated capital, ranked second among the world's most polluted cities on Thursday morning, recording an Air Quality Index (AQI) of 253 at 10:30 am.

The air was classified as 'very unhealthy', posing serious health risks, according to the AQI report of IQAir, a Swiss free real-time air quality monitoring platform.

Pakistan's Lahore topped the list, while Kolkata, India, and Kathmandu, Nepal, ranked third and fourth with AQIs of 197 and 185, respectively.

By contrast, Batam and Medan in Indonesia recorded the world's cleanest air with an AQI of 0.

According to the AQI scale, a reading between 50 and 100 is considered 'moderate', with generally acceptable air quality, though sensitive individual...