Dhaka, the densely populated capital of Bangladesh, ranked ninth among the world’s most polluted cities on Thursday morning, recording an Air Quality Index (AQI) of 153 at 9:22am.

The air quality was classified as ‘unhealthy’, indicating potential health risks for the general population, according to the AQI scale.

Dakar in Senegal, Chiang Mai in Thailand and Delhi in India occupied the top three positions on the list, with AQI scores of 299, 282 and 199 respectively.

According to AQI standards, a reading between 101 and 150 is considered ‘unhealthy for sensitive groups’, 151 to 200 ‘unhealthy’, 201 to 300 ‘very unhealthy’, while levels above 301 are deemed ‘hazardous’, posing serious health risks.

The AQI, which reports daily air quality, informs residents how clean or polluted the air is and highlights potential health effects.

In Bangladesh, the AQI is calculated based on five key pollutants: particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone.

Dhaka has long struggled with air pollution. Air quality usually deteriorates in winter and improves during the monsoon season.

The World Health Organization (WHO) estimates that air pollution causes about seven million deaths worldwide each year, primarily from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections.