The Issue of Environmental Pollution: Dhaka, Bangladesh

This study evaluates the exposure of particulate matters that accumulate indoors releasing from various indoor and outdoor sources with the use of computer model CONTAM. The city chosen for this case study is Dhaka, Bangladesh, one of the most polluted cities of the world (Page and Correspondent, 2018) (Dhaka Tribune, 2018).A new global study report published on April 2018, by Health Effects Institute (HEI), stated that although more than 95 percent global population are suffering from poor air pollution and breathing the polluted air, the main victims of air pollution are the poorest nations. The world is so severely affected by air pollution that according to this report, about 6.1 million deaths around the world in 2016 occurred due to this single cause (healthdata.org, 2018).

According to this report, air pollution is the fourth highest cause of deaths globally, standing just below high blood pressure, diet and smoking. However most of these affected people are inhabitants of low and middle income countries, especially of Asia and Africa where they face very poor air pollution indoors as well as outdoors (Page and Molla,2018).Global warming is now a serious issue for the world as it affects the environment in many ways. Air pollution is one of the impacts caused by global warming. Although a complex one, there is coherence between air quality and climate change; air quality can be affected by climate change, and climate change has an impact on air quality (US EPA,2018).A number of sources are responsible for the production of greenhouse gases and major air pollutants. Fossil fuel combustion, brick production, biomass burning etc. are some notable sources for producing black carbon that is a threat to the climate. As a major air pollutant, black carbon shows it impacts in two different ways. Firstly, it may produce heat in the lower atmosphere by absorbing the solar radiation and secondly, by depositing on Himalayan glaciers it accelerates the melting of the glaciers. Both these two incidents are impacts of global warming. From the recent studies it has been found out that black carbon is the second largest contributor of global warming (Begum, Hopke and Markwitz, 2013).

Because of its topographical location, the climate effects on Bangladesh are very significant. A number of climate changes have been observed over the last decades due to this global warming. Among these; changes in the length of seasonal variation, droughts, floods, increased water salinity, and sea level rise are notable (Begum, Hopke and Markwitz, 2013).Although developed countries play the most significant role in producing greenhouse gases, developing countries also have a growing contribution in this respect. In developing countries; biomass burning, vehicular emission and industry such as brick manufacturing are the main sources for producing the major greenhouses gases such as CO2, CO, NO2, black carbon etc. (Begum, Hopke and Markwitz, 2013). Particulate matters (PM), whether coarse (10-2.5 µm) or fine (up to 2.5 µm) have a great effect on climate change and global warming. They may cool or warm the earth’s atmosphere. As mentioned above, black carbon has a contribution on global warming. This is a particulate matter that originates from incomplete combustion. On the other hand, another particulate matter, sulphate contributes on climate change by cooling the earth’s atmosphere (US EPA, 2018).

Dhaka, the capital city of Bangladesh is now facing severe air pollution and the main contributor to this air pollution is particulate matters. As well as impacting on the climate these pose serious threats to human health. The report published by DoE (Department of Environment, Bangladesh) in 2016, states that the maximum concentration of particulate matters present in Dhaka’s air was 405 µg/m3 for PM2.5 and 543 µg/m3 for PM10 since 2002-07(Bahauddin and Salah Uddin,2010). Dhaka’s average particulate matter levels are higher than Bangladeshi standard (Bangladesh National Ambient Air Quality Standards) and far much higher than WHO guidelines. So particulate matters present in Dhaka’s air are of huge research interest nowadays.Since 2002, the Air Quality Monitoring Project (AQMP), DoE, is operating an air quality monitoring program in Dhaka. The information found from this monitoring program is, the concentration of coarse and fine particulate matters PM10 and PM2.5 found in Dhaka’s air is very much significant and possess a great health risk to the occupants of Dhaka. While the diesel engine operated vehicles are the main contributor of PM in Dhaka’s air, brick kilns and biomass burning are also responsible for the production of PM (Islam et al.,2011).

Besides construction sectors, manufacturing industries and domestic activities are other sources of PM.Although there is a big international focus on the risks posed by outdoor air pollution, indoor air can also be a prominent source of exposure. Cooking, eating, leisure time, sleeping, studying, gossiping all these activities are done at indoors. So staying indoors is not at all an insignificant part of life. Rather people spend most of their time at indoors and the activities they perform at indoors are responsible for the production of PM. Cooking, smoking, heating, walking, sweeping, dusting etc. are some of the prime domestic sources of PM generated at indoors. Cooling or heating system, insufficient ventilation, several building construction materials (asbestos etc.), health care products etc. are responsible for PM production at indoors. The outdoor sources also contribute in indoor PM concentration; if the surrounding (ambient) outdoor environment is polluted, it severely affects the indoor environment. The building patterns or geometrical shapes also play a part in indoor pollution, as they have a contribution to the ventilation and human exposure to pollutants. Thermal comfort is directly associated with ventilation system and changing the geometrical shapes of the buildings also changes the ventilation system as well as the accumulation of pollutants at indoors (Pollutants,2018).

PM is associated with a lot of health problems. PM10 and PM2.5 both can penetrate inside the lungs and through day by day chronic exposure of these particles may increase the risk of developing respiratory and cardiovascular diseases. PM exposure may also be responsible for lung cancer. Alhough coarse and fine both particles are detrimental to health, smaller particles are more dangerous than the larger particles as they can penetrate deep inside the lungs and more susceptible to create these life threatening diseases (WHO, 2013).Both developed and developing countries are experiencing the negative health impacts on their population for particulate matters exposures. Though the impact falls upon the total population but the susceptibility depends on age and health of the population.From the data provided by ICDDRB (International Centre for Diarrhoeal Disease Research, Bangladesh), the child death in Bangladesh, due to pneumonia is estimated about 50,000 and about 80,000 children under five have to admit in hospitals each year due to respiratory illness while the exact number is very likely to be higher than this value (Dhaka Tribune, 2018). From a survey it has been found that by controlling the PM concentration and reducing its level to Bangladesh air quality standard, annually around 3580 premature deaths, 10 million restricted activity days and 87 million respiratory system days could be saved successfully (Bahauddin and Salah Uddin,2010).