With an air quality index (AQI) score of 152 at 8:53 am today, Dhaka ranked 3rd on the list of cities worldwide with the worst air quality.

Baghdad of Iraq, Jakarta of Indonesia and Dubai of United Arab Emirates occupied the first, second, and fourth spots, with AQI scores of 161, 160, and 151 respectively.

Read: Continued rain keeps Dhaka's air quality ‘moderate’

An AQI between 50 and 100 is considered ‘moderate’ with acceptable air quality. However, there may be a health concern for a very small number of people who are unusually sensitive to air pollution. AQI between 101 and 150 is considered ‘unhealthy', and between 201 and 300 is said to be 'very unhealthy', while a reading of 301+ is considered 'hazardous', posing serious health risks to residents.

The AQI, an index for reporting daily air quality, informs people how clean or polluted the air of a certain city is and what associated health effects might be a concern for them.

The AQI in Bangladesh is based on five pollutants: particulate matter (PM10 and PM2.5), NO2, CO, SO2, and ozone.

Read: Dhaka's air quality ‘unhealthy for sensitive groups’ this morning 

Dhaka has long been grappling with air pollution issues. Its air quality usually turns unhealthy in winter and improves during the monsoon.

As per World Health Organization (WHO), air pollution kills an estimated seven million people worldwide every year, mainly due to increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, and acute respiratory infections.