When it comes to air pollution, Dhaka has been continuously on the top of the rankings. On October 3this year, the city ranked the worst, scoring 245 on the Air Quality Index (AQI).
Dhaka is amongst the world's most densely populated cities. According to the AQI, the air quality of this city is a major concern.
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 its residents.
For Bangladesh, the AQI is based on five criteria of pollutants – Particulate Matter (PM10 and PM2.5), nitrous oxide, carbon monoxide, sulphur dioxide and ozone. Amongst these, the particulate matters can affect our respiratory system and can also pollute the blood stream.
There are three components that mostly pollute the air. The components are smoke, vehicle emission and dust. Among these, smoke from brick kilns and vehicle emissions contribute the most to air pollution in Dhaka.
Increasing construction activities in recent years has created high demand for construction materials in Bangladesh. As the country has no alternatives to bricks, the number of brick kilns has been increasing at an estimated annual growth rate of 5-6%.
In 2013, the Bangladesh Bureau of Statistics (BBS) had reported about 4,959 brick kilns in the country, which increased to about 8,000 kilns as of 2018, according to the Clean Air and Sustainable Environment (CASE) project.
Vehicle emission is also a major source of air pollution in Dhaka. Older vehicles, improper traffic and parking management, overloading, lack of maintenance, adulterated fuel, etc., have driven the vehicle sector to contribute to air pollution in the capital.
Vehicles not only pollute the air through tailpipe emission, but also through dust emission generated from friction against the roads. The latest source apportionment study by the Norwegian Institute for Air Research (NILU) under the CASE project attributed about 10.4% of fine particles in Dhaka city to vehicular emission, and 7.7% to road dust.
However, are these the only reasons for air pollution in the city? As Dhaka is going through a major structural change, construction projects all over the city, such as the Mass Rapid Transit project, the Bus Rapid Transit project and the elevated expressway project is also contributing heavily to dust emission.
Even in daylight, it gets difficult to see clearly around the construction sites due to the heavy smog. Although these projects are necessary for the development of the country, they are taking a heavy toll on the environment.
Abu Naser Khan, chairman of Poribesh Bachao Andolon said, "It is necessary to ensure air quality, as it [air] is the most vital component for us. Brick kilns and vehicular emission contribute the most to air pollution. As we cannot fully shut down the brick manufacturing and transportation process, it is required to keep these industries under continuous surveillance, to reduce emission."
According to the AQI data, the air quality of Dhaka improves during the rainy season, but worsens during the dry periods of the year. During the rainy season, rain water helps the dust settle down.
Additionally, the brick kilns remain closed during this season as well.
But this is not a permanent solution. According to CASE, if all 7,200 Fixed Chimney Kilns were replaced by Traditional Zigzag Kilns (TZK), about 810,000 tons of coal or about Tk1,012 crore would be saved every year – meaning that each kiln would save about Tk14 lakh every year.
About 2,579 tons of PM10, 927 tons of sulphur dioxide, and 5,970.2 tons of carbon dioxide would be reduced countrywide in a day.
Recently, a media outlet in Bangladesh reported that the gasoline used in vehicles is not up to the mark. As good gasoline can reduce carbon emission, it is also necessary to ensure fuel quality as well.
Also, to reduce the amount of dust in the dry season, it is also required to properly water the constructions sites as well.
Respiratory diseases are growing day by day in Bangladesh. Even yesterday (Sunday), the air quality of Dhaka according to the AQI stood at 205 at 2:00 pm – a very unhealthy score. There are regulatory bodies in our country to monitor each and every sector that causes air pollution.
Their willingness can reduce air pollution to a great extent and make Dhaka a more liveable place.