Dhaka, Nov. 22 -- Dhaka's air quality continued to be in the 'unhealthy' zone on Tuesday morning.

With an air quality index (AQI) score of 196 at 10:20am, the metropolis ranked second in the list of world cities with the worst air quality, reports UNB.

An AQI between 101 and 200 is considered 'unhealthy', particularly for sensitive groups.

Pakistan's Lahore and Karachi occupied the first and third spots in the list, with AQI scores of 317 and 184, respectively.

An AQI between 201 and 300 is said to be 'poor', while a reading of 301 to 400 is considered 'hazardous', posing serious health risks to residents.

In Bangladesh, the AQI is based on five criteria pollutants -- Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.