Bangladesh’s capital Dhaka ranked the 10th worst city in the Air Quality Index (AQI) on Sunday morning.

It had an AQI score of 163 at 10:49am. The air was classified as ‘unhealthy’.

When the AQI score is between 151 and 200, everyone may experience health effects while members of sensitive groups may experience more serious health effects.

Pakistan’s Lahore, Vietnam’s Hanoi and Mongolia’s Ulaanbaatar occupied the top three positions in the list of cities with worst air with AQI scores of 239, 238 and 198 respectively.

The AQI, an index for reporting daily air quality, informs 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 (O3). The Department of Environment has also set national ambient air quality standards for these pollutants. These standards aim to protect against adverse human health impacts.

Dhaka, an overpopulated megacity surrounded by brick kilns, has long been battling air pollution.

Brick kilns have been identified as the leading cause of air pollution in the capital in a report by the World Bank and the Department of Environment.