, April 11 -- Dhaka, the overcrowded capital city of Bangladesh, has ranked fifth on the list of cities with the worst air quality with an AQI index of 154 at 09:09 am on Saturday.

Dhaka's air was classified as 'unhealthy', according to the air quality and pollution city ranking.

Vietnam's Hanoi, Thailand's Chiang Mai, India's Delhi and Egypt's Cairo occupied the first four spots in the list, with AQI scores of 185, 178, 167 and 164, respectively.

An AQI between 151 and 200 is considered 'unhealthy' while 201-300 is 'very unhealthy' and 301-400 is considered 'hazardous', posing severe health risks to residents.

The AQI, an index for reporting daily air quality, informs people how clean or polluted the air of a certain city is and what...