Dhaka ranked 4th among the world’s cities with the worst air quality on Friday morning, recording an Air Quality Index (AQI) score of 165 at 8:30 am.

The air quality was classified as “unhealthy,” meaning the concentration of pollutants in the air had reached a level that could pose health risks to the general population, according to the AQI scale.

Malaysia’s Kuala Lumpur and Kuching occupied the top two spots on the global pollution list, with AQI scores of 206 and 191, respectively, followed by Pakistan’s Lahore with a score of 171.

An AQI reading of 101 to 150 is considered ‘unhealthy for sensitive groups’, while 151 to 200 is classified as ‘unhealthy’. A reading between 201 and 300 is considered ‘very unhealthy’, and anything above 301 is categorized as ‘hazardous’, posing serious health risks.

The AQI provides a daily indication of air quality by measuring the level of pollution and its potential impact on human health.

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 faced serious air pollution problems, with air quality generally deteriorating during the winter months and improving during the monsoon season.

The World Health Organization estimates that air pollution contributes to around 7 million deaths worldwide every year, mainly from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.