With an air quality index (AQI) score of 174 at 9:15am today, Dhaka ranked 4th on the list of cities worldwide with the worst air quality.

Pakistan's Lahore, India's Delhi and the United Arab Emirates Dubai occupied the first three spots on the list, with AQI scores of 303, 258, and 177, respectively.

When the AQI value for particle pollution is between 101 and 150, air quality is considered 'unhealthy for sensitive groups', between 151 and 200 is 'unhealthy', between 201 and 300 is said to be "very unhealthy", while a reading of 301+ 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. 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 due to increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections.