Bangladesh's capital Dhaka ranked fifth on Wednesday in the AirVisual Index of the world's cities with the worst air quality.
In the real-time air quality ranking, Dhaka scored 164 and was classified as ‘unhealthy’, according to AirVisual.
On Tuesday, Dhaka remained on top of the air quality index for some time, scoring 361, and was also classified as 'hazardous'.
United States environmental experts developed the Air Quality Index (AQI) to rank air quality. The AQI is divided into six categories, indicating increasing levels of pollution harmful to one's health.
India's Mumbai topped the index with a score of 176, followed by Pakistan’s Karachi, and Kathmandu of Nepal.
Bangladesh, one of the most densely-populated countries in the world, has been struggling with air pollution for a long time and Dhaka continuously ranks among the world's most polluted cities.
Many environmental experts blame the ongoing construction of Metro Rail in this regard. They also identified brick kilns, vehicles running on fuel with higher sulphur levels, as well as construction work, as major sources of air pollution.
On February 9, green activists, including ‘Poribesh Bachao Andolan (Poba)’ and ‘Nagorik Odhikar Sangrakkhan Forum’, voiced deep concern, saying that around 90% of Dhaka city dwellers are affected by serious dust pollution and urged the authorities concerned to take effective steps.
They also said the intensity of dust pollution rises in winter due to road digging and delayed disposal of waste, causing the spread of various respiratory, allergy, and skin diseases.
Following this, the High Court has ordered the Director General (DG) of Department of Environment (DoE) to take steps to conduct mobile court drives twice a week against those responsible for air pollution in the city.
A new study that uses data from the Global Burden of Disease Project has found that ambient air pollution shortens an average Bangladeshi's life by 1.87 years.
The study also suggested that better air quality could lead to significant extension of human lifespan around the world.
Currently the World Health Organization (WHO) estimates that worldwide, seven million people die every year from exposure to such pollution, with most deaths occurring in low and middle-income countries, chiefly in Africa and Asia.
An AQI value over 300 represents hazardous air quality, and below 50 the air quality is good.
The index is based on the five criteria of pollutants regulated under the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulphur dioxide, and nitrogen dioxide.
The AQI debuted in 1968, when the National Air Pollution Control Administration undertook an initiative to develop an air quality index and to apply the methodology to Metropolitan Statistical Areas.
Worldwide, ambient particulate matter ranks as the sixth leading risk factor for premature deaths, according to the 2018 'State of Global Air' report.
These risks are acute in Dhaka, said the report. It also suggests that city residents are constantly inhaling particulate pollution of PM2.5, which is microscopically small at 2.5 micrometers in diameter or less, produced by all types of combustion common in the city.
