Dhaka's air quality turns to the ‘moderate’ zone this morning.

With an air quality index (AQI) score of 83 at 9:00 am, Dhaka ranked 21st on the list of cities worldwide with the worst air quality.

Pakistan’s Lahore, India's Delhi and Vietnam's Hanoi occupied the first three spots on the list, with AQI scores of 193, 184 and 171, respectively.

An AQI between 50 and 100 is considered ‘moderate’ with acceptable air quality. However, there may be a health concern for a very small number of people who are unusually sensitive to air pollution.

In Bangladesh, the AQI is based on five criteria pollutants: particulate matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.

Dhaka has long grappled with air pollution issues. Its air quality usually turns unhealthy in the 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.