Dhaka, once again recorded the worst air quality globally with an Air Quality Index (AQI) score of 266 at 9:00am this morning.

Today's air was classified as "very unhealthy", according to the AQI index.

This is the second consecutive day that Dhaka has reported the worst air quality, posing a severe health threat to its residents.

The AQI categorises air quality as "moderate" when scores range from 50 to 100, "unhealthy for sensitive groups" from 101 to 150, "unhealthy" from 151 to 200, "very unhealthy" from 201 to 300, and "hazardous" at 301 or above.

Following Dhaka, India's Delhi and Vietnam's Hanoi both recorded AQI scores of 253, and Nepal's Kathmandu reported a score of 200, placing them second, third, and fourth respectively on the list of cities with the worst air quality.

The AQI measures air quality by analysing the levels of five pollutants: particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone. It provides residents with information on how clean or polluted the air is and the potential health effects.

Dhaka has struggled with severe air pollution for years, with air quality typically deteriorating during the winter months and improving during the monsoon season.

According to the World Health Organization (WHO), air pollution is responsible for an estimated seven million deaths annually, primarily due to stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections.