Dhaka’s air quality turned ‘moderate’ on Friday morning, with the city recording an Air Quality Index (AQI) score of 79 at 9:35am.

Dhaka ranked 23rd among cities worldwide with the worst air quality at the time.

According to the AQI scale, a score of 51-100 indicates ‘moderate’ air quality. At this level, air quality is generally acceptable, although unusually sensitive people may experience some health effects.

Malaysia’s Kuching, Ethiopia’s Addis Ababa and Indonesia’s Jakarta topped the list of cities with the worst air quality, recording AQI scores of 182, 179 and 167, respectively.

Earlier, at 9:20am on Thursday, Dhaka ranked third among cities worldwide with the worst air quality, with an AQI score of 169.

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

The AQI is an index used to report daily air quality and inform people about how clean or polluted the air is and the associated health risks.

Bangladesh’s AQI is based on five pollutants: particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), sulphur dioxide (SO2) and ozone.

Dhaka has long been grappling with air pollution. Its air quality generally deteriorates during winter and improves during the monsoon.

According to the World Health Organisation (WHO), air pollution causes an estimated seven million deaths worldwide every year, mainly due to increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.