With an air quality index (AQI) score of 97 at 9:14am, Dhaka ranked 18th on the list of cities worldwide with the worst air quality on Saturday,

Pakistan’s Lahore, India’s Delhi and Uganda’s Kampala occupied the first three spots on the list, with AQI scores of 355, 353 and 166 respectively.

An AQI score between 51 and 100 is considered "moderate", between 101 and 150 is considered "unhealthy" and between 201 and 300 is said to be "very unhealthy", while a reading of 301 and above 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.

As per the World Health Organisation, 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.