Dhaka continued to occupy the top spot in the list of cities around the world with the worst air quality for the fourth consecutive day this morning.

With an air quality index (AQI) score of 322 at 9:00am, Dhaka's air quality remained in the "hazardous" zone.

China's Beijing, Pakistan's Lahore, and India's Mumbai occupied the second, third, and fourth spots in the list, with AQI scores of 214, 210, and 197, respectively.

Dhaka air was also the most polluted in the world yesterday morning with an AQI of 288.

An AQI between 151 and 200 is considered "unhealthy", 201 and 300 "very unhealthy", and 301 to 400 is considered "hazardous", posing serious health risks to residents.

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.

Air pollution consistently ranks among the top risk factors for death and disability worldwide.

Breathing polluted air has long been recognised as increasing a person's chances of developing heart disease, chronic respiratory diseases, lung infections, and cancer, according to several studies.