Dhaka ranked as the  second most polluted city in the world with ‘very unhealthy’ air quality on Tuesday morning.

Dhaka’s air quality index (AQI) score was 268 at 10 am today.

An AQI between 201 and 300 is said to be ‘very unhealthy’, while a reading of 301 to 400 is considered 'hazardous', posing serious health risks to residents.

India’s Kolkata and Kyrgyzstan’s Bishkek occupied the first and thirs spots in the list, with AQI scores of 278 and 230, respectively.

Read more: Dhaka's air quality turns ‘very unhealthy' this morning

An AQI between 101 and 200 is considered 'unhealthy', particularly for sensitive groups.

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. Its air quality usually turns unhealthy in winter and improves during the monsoon.

Air pollution consistently ranks among the top risk factors for death and disability worldwide. Breathing polluted air has long been recognised as increasing a person’s chances of developing a heart disease, chronic respiratory diseases, lung infections and cancer, according to several studies.

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

The worsening air quality of Dhaka city is threatening the health status and life of its residents.