Dhaka: Dhaka's air was classified as "poor" or "very unhealthy" as the mega city ranked the second worst in the Air Quality Index (AQI) on Sunday morning.

Dhaka's AQI score was recorded at 212 at 10:21am, while Pakistaninfo-icon's Lahore and Afghanistaninfo-icon's Kabul occupied the first and third spots with AQI scores of 221 and 190, respectively.

An AQI between 201 and 300 is said to be "poor", while a reading of 301 to 400 is considered "hazardous", posing serious healthinfo-icon risks to residents.

The AQI, an index for reporting daily air quality, is used by government agenciesinfo-icon to inform people how clean or polluted the air of a certain city is and what associated health effects might be a concern for them.

In Bangladeshinfo-icon, 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 during winter and improves during monsoon.

A report by the Department of Environmentinfo-icon (DoE) and the World Bankinfo-icon in March 2019 pointed out that the three main sources of air pollution in Dhaka "are brick kilns, fumes from vehicles and dust from construction sites".

With the advent of winter, the city's air quality starts deteriorating sharply due to the massive discharge of pollutant particles from construction work, rundown roads, brick kilns and other sources.

Air pollution consistently ranks among the top risk factors for death and disability worldwide. Breathing polluted air has long been recognized 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 Worldinfo-icon Health Organization (WHO), air pollution kills an estimated 7 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.