Dhaka's air was classified as "hazardous" this morning.

With an AQI score of 352 at 9:04 am, Dhaka's air quality was ranked second worst in the world, according to the air quality index.

India's Delhi, Pakistan's Lahore occupied the first and third spots on the list, with AQI scores of 437, and 245 respectively.

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 a heart disease, chronic respiratory diseases, lung infections and cancer, according to several studies.

As per the World Health Organization (WHO), air pollution kills an estimated seven million people worldwide every year.