Bangladesh is a country located in the southern region of Asia. It has seen in recent years a massive amount of economic growth as well as a population boom, with some 162 million or more people calling Bangladesh their home. This makes it the 8th most populous country worldwide, with a close proximity to other countries such as Myanmar, India, Nepal and China, many of which suffer from their own pollution related issues, with the economic giants of India and China taking many of the top spots in regards to most polluted cities across the globe.
Observing the pollution readings taken over the last few years, it is clear to see that Bangladesh has some fairly severe issues with its pollution levels, so much so that it actually takes the number one spot out of the most polluted countries ranked worldwide, along with its capital city Dhaka taking the 21st spot in terms of most polluted cities ranked over 2019. These are positions that indicate that Bangladesh has a pollution crisis in its hands.
Once again in 2019, Bangladesh as a country came in with a PM2.5 reading of 83.30 μg/m³, that as mentioned put it in 1st place. This reading would also place it into the middle to higher end of the ‘unhealthy’ ratings bracket, which requires a PM2.5 reading of any number between 55.5 to 150.4 μg/m³ to be classed as such. PM2.5 refers to any fine particulate matter that is 2.5 micrometers or less in diameter, and due to its extremely small size has a highly negative effect on the health of anyone who breathes it. As such it is one of the major components used in the calculation of overall pollution levels, with other pollutants such as PM10 and ozone (O3) being figured into the equation as well.
Whilst there would be many natural areas of pristine beauty and clean air around Bangladesh, particularly in rural areas, the extremely poor placing in terms of its pollution levels is due to major cities such as Dhaka. With the rise of rapid urbanization often comes a massive influx of rural to city migration, which has a compounding effect on the pollution levels.
Growth in the population comes with an increase in cars, larger demand for homes as well as a boom across all industries. As mentioned, whilst there would be many areas of Bangladesh that do not fall under these terrible ratings as a whole, the capital city is of prime focus for the country’s pollution levels, and with its growing population, a solution to these disastrous levels of smoke, haze and pollutants in the atmosphere must be addressed.
Whilst Bangladesh sees many sources of pollution, there are several that stand out as being main instigators in the awful levels of pollution seen. In the most simplistic take on pollution causes, which is not only native to Bangladesh but an eternal problem worldwide, is that of vehicle usage. With a vast amount of cars, motorbikes, buses and trucks dominating the roads, it is inevitable that large amounts of pollution are going to be emitted from these in the form of exhaust fumes.
Of note is that there is a distinct lack of regulations regarding the state and quality of the engines and motors that can be used, and as such in a similar fashion to other highly polluted countries such as Nepal, there are many cars, motorbikes and buses that are kept in use long after they should have been taken off the road. These ancient machines, running on fossil fuels such as diesel, spew out large amounts of black soot, sulfur and other toxic compounds and gases that all contribute to the high levels of year-round ambient pollution, far much more so than a cleaner or less ancient counterpart would.
Besides the vehicular emissions, Bangladesh also has its industrial fumes to worry about, with heavy concentrations of both factories and small-scale local businesses operating within the cities. Of particular salience is that of the brick kilns, with cities such as Dhaka being famous for its high output of bricks, producing estimated numbers of well over a billion bricks per year.
These kilns, often run by small scale family-based operations (although extremely high in number across the cities) rely on the burning of materials such as coal, wood and any other combustible items that can be obtained, such as black rubber tires or synthetic materials such as plastic, which release heavy amounts of highly toxic black soot.
Besides the heavy use of these kilns, often referred to repeatedly in media outlets because of their heavy pollution contributions, along with public acknowledgement that it is doing so (with no proper enforcement or punishment yet in sight for offender), there is also the problem of dust accumulation within the city, something that is not normally acknowledged as a pollutant, but with high levels of PM2.5 and PM10 finding their origin from the various types of finely ground dust, they are also a large contributing factor to Bangladesh's air quality problems.
So, to summarize, the main causes of pollution in Bangladesh are vehicular emissions, fumes from factories and brick kilns, as well as dust accumulations from various sources, all of which will be discussed in further detail.
To address the emissions given out by the various kinds of vehicles first, they would include the standard ones such as carbon monoxide (CO), ozone, nitrogen dioxide (NO2) and sulfur dioxide (SO2). Out of all of these, nitrogen dioxide would see the most prominence in the atmosphere over any given area that sees a high level of traffic or large volume of vehicles moving through it, particularly at peak times such as rush hours or mass commutes in and out of the cities. Nitrogen dioxide is so pertinent in its release from vehicles that its concentration in the atmosphere can often be used to determine exactly how much pollution is being caused by traffic alone.
Besides the standard vehicle pollutants mentioned, when diesel fuel comes into the equation the aforementioned chemical compounds are often released in far greater numbers, accompanied by other dangerous pollutants such as black carbon and volatile organic compounds (VOC’s). Among the VOC’s you would find chemicals such as benzene, formaldehyde and methylene chloride. All of these have adverse effects on human health, and a tendency to become gases at room temperature, making them more dangerous as in their gaseous form it is far easier to respire. The volatile aspect of their name refers to this property of evaporating into a gas at a much lower temperature.
Black carbon is also found released alongside the aforementioned chemicals, as well as being a major component in soot, being released in large volumes from the burning of wood, coal and various types of organic refuse. It has many damaging properties upon inhalation, including increased rates of cancer, scarring of the lung tissue as well as damage to the heart due to its ability to enter into the blood stream via the lungs.
Besides this it also has a number of disastrous consequences on the environment and climate, as well as affecting the temperature within a city, having knock on effects on the quality of people's lives, showing just how far reaching and insidious all forms of pollution are.
Black carbon has the unique property of being able to absorb solar radiation and release it as heat, and with large accumulations of this taking place due to its heavy release from factories, brick kilns and automobiles, it would be found in high amounts permeating both the atmosphere and roads across Bangladesh.
Other pollutants that would be released from the combustion of the kiln fire materials would include furans, dioxins, lead and mercury, polynuclear aromatic hydrocarbons and polychlorinated biphenyls. All of these have disastrous effects on the health of humans, wildlife and vegetation.
With the plethora of previously mentioned pollutants and fine particulate matter in the air in Bangladesh, there come along with it a large number of health issues, most pertinent when the pollution levels are at their highest (such as in January and December in Dhaka with their readings of 181.8 μg/m³ and 146.3 μg/m³ respectively), although of note is that even at lower concentrations of pollution there will always be a risk for adverse effects.
Amongst vehicular pollution, with pollutants like nitrogen dioxide and carbon monoxide being prominent in the atmosphere, symptoms such as irritation to mucous membranes such as the mouth, inner nose, eyes, throat and stomach become possible. There also becomes a risk for increased bouts of chest infections, that lead to further susceptibility to respiratory conditions such as influenza and pneumonia.
When exposed to PM2.5 and PM10 arising from both fires as well as fine dust accumulations, rapid aging of the lungs can occur, with their capacity being reduced due to scarring as well as the alveoli, or small air sacs in the lungs becoming filled with PM2.5, lowering its ability to fully take in oxygen and pass it over the bloodstream unabated.
With a shortness of oxygen available to the body, side effects such as ischemic heart disease become possible, something that occurs when an organ fails receive enough oxygen to keep the tissues at a healthy and full functioning level. This can in turn have knock on effects of increased rates of heart attacks, arrythmias, strokes, problems related to blood pressure and an overall increase in mortality rate.
As mentioned, the extremely small size of PM2.5 allows it to find its way into the air sacs of the lungs, whereby it can accumulate and cause increased risks of lung cancer (as well as the decrease in full lung function), but in other instances it can actually cross over the blood barrier via the lungs and makes its way into the bloodstream and to every part of the body via the circulatory system.
This can wreak havoc on the human body, with all organs being susceptible to damage, in particular those that have filtration roles such as the hepatic and renal systems (liver and kidneys). Damage to the blood vessels can also occur, as well as other areas of the body such as the reproductive system being affected, having ruinous effects on fertility rates and reproductive health as a whole.
Young children who are exposed to high levels of pollution can end up with developmental problems due to pulmonary issues, which can stunt growth as well as cause cognitive impairments. Once children suffer from multiple bouts of respiratory illnesses such as pneumonia, not only does the child mortality rate go up, but the chance of them having lifelong issues related to the health of their lungs and an increased susceptibility to further respiratory ailments goes up.
Pregnant mothers are also highly vulnerable to pollution levels, with disastrous effects on their unborn babies occurring. Instances of miscarriage or stillbirth go up significantly (thus adding to the infant mortality rate in Bangladesh), as well as chances of the child being born severely underweight, or prematurely. As such it is important to highlight the large number of health risks that can happen to every part of the population, and preventative measures become increasingly important, such as the wearing of high-quality air filtering masks, as available on site, as well as staying up to date on pollution levels on any given date via air quality maps, available on the AirVisual app as well as the IQAir website.
Whilst it may seem a daunting task that may require years of collective work from both the government and citizens, dents may be put into the levels of pollution via the implementation of fines and punishments for those that exceed air pollution levels in any given areas, whether they are large scale industrial factories or small-time brick kilns operated out of a family home or shop. Education is also paramount in this, with the educating of the general population to the disastrous effects of pollution so that they may reconsider the materials that they burn before doing so.
Others would include the eventual removal of ancient vehicles off the road, as well as a move to cleaner fuel sources and phasing out of diesel fuels in automobiles across the country. As stated, a highly concentrated effort would need to take place over the coming years, if Bangladesh is to see its position as worlds most polluted country changed for the better.