Air pollution still remains one of the top-most challenges for Bangladesh and Dhaka was ranked as the fourth most polluted city in the world with ‘unhealthy’ air quality on Wednesday (November 30, 2022) morning. Dhaka’s air quality index (AQI) score was 186 at 10.15 am today. An AQI between 201 and 300 is said to be ‘very unhealthy’, while a reading of 301 to 400 is considered 'hazardous', posing serious health risks to residents. Read: Noise pollution: The lethal soundtrack to life in Dhaka Pakistan’s Lahore, India’s Delhi and Pakistan's Karachi occupied the first three spots in the list, with AQI scores of 505, 320 and 243, respectively. An AQI between 101 and 200 is considered 'unhealthy', particularly for sensitive groups. Read: Effects of Air Pollution on Unborn Children, Neonates, Infants In Bangladesh, the AQI is based on five criteria pollutants -- Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.