Dhaka ranked 4th among the world's most polluted cities on Thursday morning, recording an Air Quality Index (AQI) score of 147 at 9:50 am. 

According to the AQI scale, the city's air quality was classified as “Unhealthy for Sensitive Groups”, poses health risks to children, older adults, and people with heart or lung diseases, while the general public is mostly unaffected.

Portland of USA topped the global pollution list with an AQI score of 168, followed by Kampala of the  Uganda with 160 and Kinshasa of DR Congo with 159.

According to AQI standards, a reading between 101 and 150 is considered ‘unhealthy for sensitive groups’, 151 to 200 ‘unhealthy’, 201 to 300 ‘very unhealthy’, while levels above 301 are deemed ‘hazardous’, posing serious health risks.

The AQI, which provides daily updates on air quality, indicates how clean or polluted the air is and highlights potential health impacts.

In Bangladesh, the AQI is calculated based on five major pollutants: particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone.

Dhaka has long struggled with air pollution, with air quality typically worsening in winter and improving during the monsoon season.

The World Health Organization estimates that air pollution causes around seven million deaths globally each year, mainly due to stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.