Dhaka has once again topped the list of cities worldwide with the worst air quality, with an AQI of 174 at 9:20am on Tuesday.

The air was classified as 'unhealthy', according to the air quality and pollution (city) ranking.

An AQI between 151 and 200 is considered 'unhealthy' while 201-300 is 'very unhealthy', and 301+ is considered 'hazardous', posing severe health risks to residents.

The United Arab Emirates' Dubai and Indonesia's Jakarta occupied the second and third spots in the list, with AQI scores of 166 and 160, 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.

The AQI in Bangladesh is based on five pollutants: particulate matter (PM10 and PM2.5), NO2, CO, SO2, and ozone.

Dhaka has long been grappling with air pollution issues.

As per World Health Organization (WHO), air pollution kills an estimated seven million people worldwide every year, mainly due to increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections.