The air quality in Bangladesh has been declining over the years at an alarming rate. It worsens significantly during the winter in Dhaka.
So much so, that five among the top 10 causes of death in Bangladesh is related to air pollution, according to the World Health Organization.
Dhaka scored 556 in the Department of Environment’s Air Quality Index (AQI) on January 29, which has been labelled as ‘extremely unhealthy’.
But in Bangladesh, Narayanganj’s air was identified as most polluted with a 565 score in AQI. Chittagong scored the lowest at 174 and the city’s air was categorized as ‘unhealthy’.
With a respective score of 264 and 274 in the AQI, air condition in Sylhet and Barisal was tagged as ‘very unhealthy’.
However, the air pollution in Gazipur, Khulna and Rajshai was dubbed ‘extremely unhealthy’ due to a high level of pollution.
Of the total 11 air quality measuring stations in Bangladesh, three are located in Dhaka, two in Chittagong and one each in Gazipur, Narayanganj, Khulna, Rajshahi, Sylhet and Barisal.
Usually, the level of air pollution worsens in the dry months – from October to April – when scant rainfall makes matters worse.
The government has identified brick kilns, construction works as well as vehicles run by fuels with high levels of sulfur as the major sources of air pollution.
World’s most polluted
Dhaka topped the list of US Air Quality Index (AQI) for having the worst air pollution in the world on January 30.
Data obtained from smartphone application AirVisual shows the user real-time air pollution index of any city across the globe. A real-time map of the US AQI, found on web portals aqicn.org and waqi.info, also supported the data found in the application.
The index terms the air quality of Dhaka extremely unhealthy, as the city consistently ranks between 301 and 500.
“There is no denying that the quality of Dhaka’s air is quite terrible,” said Md Ziaul Haque, director (air quality management) of the Department of Environment.
He noted that the air quality usually started dropping in October every year.
“At least a thousand brick kilns operate in and around the city during winter. It is one of the reasons behind the bad air quality here,” Ziaul added.
The US Environmental Protection Agency (EPA) developed the AQI to report air quality. This AQI is divided into six categories, indicating increasing levels of health concern.
An AQI value of over 300 represents hazardous air quality and below 50 indicates that the air is good.
The index is based on five criteria pollutants regulated under the Clean Air Act – ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
Last year, a study report of World Health Organization claims that although particulate pollution levels are quite high in the capital, it is 44th among the cities it monitors, in terms of fine particle (PM2.5) pollution. In terms of PM10, or coarse dust pollution, it ranks 71st.
According to WHO, PM10 and PM2.5 can penetrate and lodge deep inside the lungs. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as lung cancer.
Among the top 10 causes of death in Bangladesh, five of them – lung cancer (13%), lower respiratory infections (7%), chronic obstructive pulmonary disease (7%), ischemic heart disease (6%), and stroke (5%) – are related to air pollution.
According to the National Institute of Diseases of Chest and Hospital (NIDCH), nearly seven million people in Bangladesh suffer from asthma – over half of them children.
Ziaul Haque suggested that that air pollution could be minimized during the dry months if concerned authorities like the city corporations and Bangladesh Road Transport Authority worked together.
“We [DoE] have been trying to suggest different measures but they are not working,” he added.
Meanwhile, DoE, in collaboration with Clean Air Asia, has initiated a project to reduce black carbon from heavy-duty diesel vehicles and engines in order to achieve a pollution-free environment within a certain period of time.
Under this initiative, the government has been considering using low sulfur diesel in vehicles and engines.
To introduce low sulfur diesel, the government has been preparing a roadmap which will work as a guideline to cut the use of high sulfur content energy.
According to the draft roadmap, import of diesel containing over 500ppm sulfur content will not be allowed from this year and the imported fuel will go through the distribution network without blending.
In addition, the import of diesel with 350ppm or less sulfur content will only be allowed from 2020. The ceiling of 50ppm sulfur content for imported diesel will go into effect by 2023.
Currently, the upper limit of sulfur content in diesel fuel in Bangladesh is 2500ppm. High sulfur content in diesel is partly responsible for particulate matter which is a major pollutant from diesel vehicles.