Bangladesh’s capital Dhaka ranked first among cities with the worst quality in the Air Quality Index (AQI) on Friday morning.

It had an AQI score of 202 at 8:13 am.The air was classified as ‘very unhealthy’.

Thailand’s Chiang Mai and China’s Shenyang occupied the second and third positions with AQI scores of 192 and 165 respectively.

When the AQI value is between 201 and 300, the entire population is more likely to be affected.

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 has long been grappling with air pollution. The air quality usually improves during monsoon.