Dhaka has long been grappling with air pollution issues

Dhaka's air quality was unhealthy on Sunday morning.

With an air quality index (AQI) score of 158 at 9:15am, Dhaka ranked ninth in the list of cities worldwide with the worst air quality.

India's Delhi, Thailand's Chiang Mai and Pakistan's Lahore occupied the first three spots on the list, with AQI scores of 306, 250 and 212, respectively.

An AQI score between 151 and 200 is considered unhealthy, a reading between 201 and 300 is very unhealthy and 301–400 is hazardous, posing severe 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.

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