Dhaka’s air quality continued to be in the ‘unhealthy for sensitive groups’ zone on Thursday.

With an air quality index score of 108 at 8:37am, Dhaka ranked 31st in the list of cities around the world with the worst air quality.

India’s Delhi, Uzbekistan’s Tashkent and Pakistan’s Karachi occupied the first three spots, with AQI scores of 237, 187 and 182, respectively.

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

Similarly, 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.

AQI, an index for reporting daily air quality, is used by government agencies to inform people how clean or polluted the air of a certain city is, and what associated health effects might be a concern for them.

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

Dhaka has long been grappling with air pollution issues. Its air quality usually turns unhealthy in winter and improves during the monsoon.

With the advent of winter, Dhaka’s air quality starts deteriorating sharply due to the massive discharge of pollutant particles from construction work, rundown roads, brick kilns and other sources.