AN OVERVIEW OF HEALTH AND ENVIRONMENTAL THREATS FROM THE BRICK KILN INDUSTRY AROUND THE CAPITAL OF BANGLADESH

Bangladesh is one of the top brick manufacturing countries in the globe. With rapid urbanization and industrialization, the brick manufacturing industry is elevating to its peak level day by day and contributing to the country’s GDP significantly. This research aims to investigate the current environmental and health threat coming from brick kilns around the capital of Bangladesh. The selected areas are Savar, Tongi, Amin Bazar and Ashulia. The methodology followed in this study was field surveying in the selected areas and information acquisitions from the secondary data. Results from this study revealed that brick kilns are highly responsible for environmental pollution that subsequently deteriorates the air quality, causes land degradation, threatens biodiversity and poses a potential impact on human health. Results also revealed that there are mainly four types of brick kilns found in selected areas e.g. Chimney Kiln (CK), Zigzag kiln (ZK), Hoffman Kiln (HK) and Hybrid Hoffman Kiln (HHK). Of these, the Fixed Chimney Kiln is found to be very obsolete at present days and creates environmental pollution at different levels. Besides these, strict implementation of the Brick Manufacturing and Brick Kilns Establishment (Control) Act, 2013 in the studied locations is still far away. This paper urges the attention of the policymakers as well as the researchers to prioritize the solution to this promising but ever-increasing pollution-causing industry of Bangladesh in sustainable ways. © 2022 by the authors. Licensee ACSE, USA. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativec ommons.org/licenses/by/4.0/).


INTRODUCTION
Brick kilns are very promising sectors of Bangladesh. This sector supporting the ever growing urbanization and industries with production eligibility of 12 billion pieces of bricks/year. There are approximately 5000 brick kilns throughout the country and this figure will be increased is by 50% in the year of 2020 (UNDP, 2011a;World Bank, 2006;Darain et al., 2013;Gomes & Hossain, 2003). Brick kilning industry contributing to the country's % 1% of GDP with the employment of nearly 1 million people. Studies conducted by UNDP revealed that every year Bangladesh is producing 1200 crore pieces of bricks to cope with the rapid urbanization rate of about 7-8% (UNDP, 2011a). However, this big economic market also poses potential losses to the environment. For this reason, the objective of this study was set to evaluate the environmental and health threats coming from the brick kiln industries. Alternative brick kiln industries were also considered since they are emitting less pollutants. Possible recommendations were also included to overcome the problems. Thus this study could be used as base line study regarding brick kiln industry induced environment and health threat in perspective of Bangladesh.

LITERATUR REVIEW
The reasons of abundance manufacturing of brick are due to availability of alluvial soil and scarcity of stone materials. Conventional methods are followed to make bricks in Bangladesh and no precaution with environmental factors like fume toxicity and emitted particles are considered. The main fuel used in brick kiln is low grade coal and firewood. Besides these, tires and natural gas are also used (Ahmed & Hossain, 2008;DoE, 2017).
These fuel create toxic fumes and particulate matters of different types that deteriorate the environment with increasing heat effect in nearby city areas including Narayanganj, Savar, Tongi, Amin bazar, Ashulia, Keraniganz, Gazipur etc. The air quality and cropping yield in the vicinity of these areas are largely affected. The use of low grade fuel, error in chimney design, breaking the legal laws and establishing unplanned brick kiln adjacent to the crop land and residential area pose potential threat to both human and environment (Siddique et al., 2014). The conventional brick field in the vicinity of city area of Bangladesh manufacture more than 18 billion pieces of bricks that require 20 tons of fossil fuel that subsequently reduce the annual crop production and accelerates the greenhouse effects. Study found that manufacturing of 3.5 billion pieces of bricks require 0.85 million tons of coal annually causing about 2,200-4,000 early stage death with 0.2-0.05 million respiratory disease cases in and around capital Dhaka (Ahmed & Hossain, 2008).
Another study revealed that about 23 tons of coal or 3,500 ft 3 of trees are required to fire up 1,00,000 pieces of brick (Roy, 2012). This amount of wood constitutes 2.52 million hectares equivalent to 17.4% of forest area (BBS, 2011). World Bank reported that air quality of Dhaka has been deteriorating due to pollution from vehicles, metal smelters, road dust and brick kilns worsen the scenario (World Bank, 2006). In addition, brick kilns are the root causes of destroying crop land and its fertility (Khan et al., 2007). The infertile land cannot be used for cropping for several years (Khan et al. 2007).

MATERIALS AND METHODS
Field based survey was done to assess the current pollution scenario from the brick kiln industries in Bangladesh. The selected area was Savar, Tongi, Amin bazar and Ashulia. Alternative brick field was also visited. It was found that alternative brick kiln was less polluting site than other conventional brick fields. Secondary data from literature reviews also considered to evaluate the environmental pollution and health threats from the brick kilns. The overview of current brick manufacturing industry is given in Table 1 (Guttikunda & Khaliquzzaman, 2014;Ahmed & Hossain, 2008 Brick field 5,000 2.
Rate of Brick production in a year 17.2 billion 5.
Gross domestic product value 1.0%
Cost of imported coal for brick kilns 22.6 billion BDT (322 million USD) 9.
Total employment in brick industry 1 million people 12.

13.
Expected growth between 2010-2020 2-4% Table 2 displays the characteristics of bricks in studied locations by field survey.

Existing Brick Making Technologies in Bangladesh
There are basically 4 categories of kiln technologies observed in the studied locations. The fixed chimney kiln (FCK) and bull's trench kiln (BTK), consist more than 90% of kilns in Bangladesh creating environmental pollution significantly. For this reason, BTK technology has already banned in Bangladesh. The two other technologies are natural gas fired Hoffmann kilns and coal fired zigzag kilns. These two technologies are relatively environmental friendly than FCK and BTK.

Fixed Chimney Kiln (FCK)
FCK is mostly used technology in the country. Though this technology requires low investment, it degrades the environment very badly. FCK is mostly seen in the north side of the capital remain operational for 6-7 months in a year. FCK is an upgraded version of BTK technology. The height of the chimney was 30 feet for BTK while it is now 120-130 feet for FCK.
This elevated height offers efficient passage of gases than BTK. FCK is basically found in large land especially on the surface level.

Zigzag Kiln
Zigzag technology used in the country is basically the replication of Indian brick manufacturing technology. It is mostly seen in the Comilla region. This kiln shows high energy efficiency with lower emission if properly constructed and operated. The reason of high energy efficiency is due to efficient burning of the bricks. Another positive side of this kiln is that it requires less fossil fuel and complex air flow outlet. The shape of the zigzag kiln is rectangular with 250 feet length and 80 feet wide. The height of the chimney is 55 feet. The kiln has 44-52 chambers. This makes better burning of the brick in zigzag pattern. All of these cause efficient fuel use, and better brick grade than FCK. However, zigzag kilns in Bangladesh is operating with lack of proper maintenance and design and do not reduce the pollutants at desired level.

Hoffman Kiln (HK)
This technology was widely used in Europe during the mid-19 th century and developed by Germany later. During the year of 1980s, this technology was adopted in Bangladesh. The rectangular shaped Hoffman kiln is 400 feet long and 70 feet wide. The height of the chimney is 100 feet. An adjust fan is placed at the bottom of the chimney. This technology possesses very good insulation system. The possible usage of natural gas as fuel further reduce the emissions. However, HK requires special building expertise. One of the advantages of HK is that the brick production can remain operational all around the year. Another advantage is that HK has roof system and monsoon season does not hamper its production rate.

Hybrid Hoffman Kiln (HHK)
This method is developed by China and is the upgraded version of HK technology. The main difference between these two technologies is in fuel usage that is HHK run by coal instead of natural gas thus upgrade the brick quality and reduce the air pollution. This technology was first introduced in the country in 2006 by GEF supported project (UNDP, 2011). About ten HHKs are running in Bangladesh at present and many more in its way to build. The HHK constitutes efficient heat optimization technology named forced draft tunnel kiln (FDTK) to produce environmental friendly bricks. Another positive site of this technology is that this does not require tall chimney like the other kilns. However, there are challenges to adopt this technology. First, establishment of HKK needs large capital investment when compared to other brick kiln technologies. Second, HHK needs larger high land area that is hardly found and very costly especially near sub-urban areas of a major city. Following Table 3 displaying the different brick manufacturing technologies in brief <2,500 <2,500 4,500-6,000 Brick unit price (BDT) 5.5-6.0 5.5-6.0 7.0-7.5

Pollution Emitted From Brick Field and Their Consequences
The commonly used fuel for brick field in study areas are wood and fossil fuel. They emit the greenhouse gases (GHGs) e.g. carbon dioxide, methane etc. (Lee et al., 2013;Chuah et al., 2006;Zong et al., 2002;Co et al., 2009). Besides that, the combustion of clay and fuel during brick manufacturing produce PCBs, PBBs dioxins and volatile liquid as extra products. These byproducts reacted with chlorine and remain for several months to year together and can even fly country to country. Another negative side is that these volatile compounds have bio accumulative characteristics because of having strong affinity to fats that subsequently create toxicity in the ecosystem thus is hazardous to flora and fauna (Hilten et al., 2008;Yarin, 1993).  Studies found that this emission level deviated with the season. For example, pollutant concentration from the brick kiln is higher in the winter (Begum & Hopke, 2013). The reason behind this is the low precipitation and stagnant wind (Akpinar et al., 2006).
Another report of World Bank, 2014 published that about 9.8 million tons of GHGs are being emitted by brick kiln in Bangladesh every year while the total CO2 emission in Bangladesh was noted to be 15.67 million tons in 2017 (Al Faruque, 2017). Using of low grade coal as fuel in the brick kilns further increase the CO2 emission and can be recognized as one of the driver factors of climate change. The consequences of climate change rise the sea level and aerial heat, change the rainfall pattern and accelerates the frequency of natural disaster like cyclone, floods etc. significantly that create negative impacts in the country's economic growth (Hossain, 2004).

Impact on Land
Conventional brick kilns in study areas use clay as the main raw material of brick manufacturing. Alam, 2009 suggested that it takes 500000 to 1000000 cft top soil to produce 3-4 million pieces of brick. It is obvious that the loss of top soil is even bigger in the present year. This scenario also results the loss of farm lands and their fertility that directly hampering the national food reserve. In addition, areas near one or more brick kilns facing reduction in crop yield due to presence of air pollutants in the atmosphere. Nutrients present in the top soil are Ca, Mg, B, Mo, Fe, Mn, N, P, K, S, Zn etc. All of these nutrients are essential to grow crops. So the affected land remains fallow for several years that subsequently affect the country's net crop production (Roy & Roy, 2016).

Impacts on Biodiversity
Studies found that each brick kiln requires at least 80000 kg of wood to run the operation each year (Daily Star, 2011). This makes destruction of trees and shrinkage of the forest cover every year. Ash and other dust particles from brick kilns hinder photosynthesis process. The fruit bearing trees adjacent to the brick kiln lost their regular size and quality. (Hossain, 2015). Besides these, the heated smoke from chimney degrade fruit quality, flower and other vegetative body since it is responsible to exceed the optimum temperature of photosynthesis phenomena. Again this hot fume is also responsible for the slow death of nearby trees (Daily Star, 2018).

Impacts on Human Health
Many of the brick kilns in studied areas are mostly situated near the crowd areas. The inhabitants of these area are facing different chronic and acute disorders. This type of toxic gases is carcinogenic, reduce eye contact capacity and cause skin diseases. (Jerin et al., 2016). The CO emitted from brick field reduce air O2 concentration thus lead to breathing difficulties. Both the aged and children generation suffer most. The children are suffered from fever frequently while the elder often suffered from bronchitis and asthma (Shams et al., 2015). Particulate matter pollution is also produced from brick kilns. WHO, 2018 reported that about 7 million people become death every year because of the presence of excessive particulate matter in the air as it enters into the lungs and cardiovascular system (Alam, 2019).

Laws Regarding Brick Kiln in Bangladesh
The Bangladesh government however, made the Brick Manufacturing and Brick Kilns Establishment (Control) Act, 2013 to protect the environment and biodiversity and to further the development of the country. This Act has 25 sections and has been come into force on 1st July 2014.

License for Establishing Brick Kiln and Brick Making
Establishing brick kiln and making any brick except block brick without license given from the District Commissioner of concerned area is illegal for anyone. On other hand, no brick can be framed in any place except in the brick kiln defined in this act.

Controlling and Reducing of Using Mud
Any kind of clay collected from arable land or hill or hillock can be used as raw materials for brick making. Getting preapproval of the District Commissioner, anyone can collect clay from any other place though the source of the clay with affidavit shall be included in his license for brick making. In addition, hollow brick or block brick shall be made in the area determined by the government to reduce the exploitation of clay for brick making. Block brick making may be made mandatory by the government to reduce the excessive use of clay.

Provisions for fuel using
No one can use wood as fuel in making brick though he is allowed to use coal. Coal, however, exceeding the determined standard sulfur, ash, mercury, or any other element of the same kind can be used as fuel for burning brick.

Prohibited Place for Brick Kiln
Any residential, protected or commercial area, city corporation, municipal area, or center of Upazila (local administration), any forest whether it may be owned by the government or any person, crop land, environmentally vulnerable area etc. shall be prohibited for establishing any brick kiln. And no authority of the Department of Environment or any other organization after the commencement of this act provide license or any kind of approval for establishing brick kiln in those places.

Provisions for Issuing License
To get a license for establishing a brick kiln, a person shall have to make an application in the prescribed manner in 'Form-A' of the Schedule of this act to the District Commissioner or any officer empowered by him of the district where the kiln locates. The application shall accompany by the prescribed fee and all documents concerned to the kiln. The application, however, is not allowed without an environment clearance certificate issued by the Department of Environment under the Environment Conservation Act, 1995. After application, District Commissioner shall be sent it to the investigation committee and order the committee to resent it with their recommendation. If the District Commissioner is pleased with the recommendation made by the Committee, issue a license for making brick in 'Form-B' of the Act.

Penalty for Offence
In this existing Act, the maximum imprisonment is 5 years while punishment can be given up to 20 lacs Taka

Barriers/Challenges
The challenges in the brick kilns of Bangladesh are- The Brick Manufacturing and Brick Kilns Establishment (Control) Act 2013 has not defined responsible authorities that would enforce the law with specific procedure.  Most of the brick field owners are politically influential persons and do not have any concern on regulatory matters and environmental consequences.  Nor rules and regulation in using of alternative bricks.  Lack of comprehensive programs to make the brick industry environmental friendly with profit.  No activity to enhance energy efficient technology that ultimately reduce the production cost.

Potential Alternatives
The Housing and Building Research Institute (HBRI) of Bangladesh has done investigation to establish alternative bricks. Thermal block, compressed stabilized earth block (CSEB), sand-cement Hollow Block and Interlocking CSEB are some of research findings of clay brick alternatives. Their insulation capacity is high. The block size is about 16"×4.5"×8" with nearly 3 kg only. It's crushing strength is 5-6 MPa with water bearing capacity <10%. A comparative scenario between traditional clay made brick and alternative is displayed in Table 5 (based on Field Survey and Ahmed & Struges, 2014). Size (inch) 9.5"×4.5"×2.75" 16"×4.5"×8" (this size can be customized) 2.
Making time Slow Fast 4.
Thermal conductivity High Low 12.
Fire CONCLUSIONS Though the brick kiln industry in Bangladesh is a promising sector in terms of economical point of view, it also degrades the environmental quality in different ways. It is high time to think about it and put emphasize to manage this sector in a sustainable manner. The following recommendations could be some of the good options- Preparing short term policy for the existing brick kiln and long term policy for the future brick kiln to protect the environmental degradation.  Motivating the brick kiln owners to switch into environmental friendly kilns or alternative kilns with financial support.  Prepare effective training and awareness programs for both owners and consumers.  Give importance to do more research to establish sustainable technology in perspective of country's economy.  Increase strict monitoring and proper enforcement of the existing laws related to brick kilns. Since Bangladesh is already ranked as mostly polluted countries in the world, there is no alternative to coming back from existing trends and moving forward to sustainable solution in brick kiln industry of Bangladesh. Institutional Review Board Statement: Ethical review and approval were waived for this study, due to that the research does not deal with vulnerable groups or sensitive issues. Funding: The authors received no direct funding for this research. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: The data presented in this study are available on request from the corresponding author. The data are not publicly available due to restrictions.

Conflicts of Interest:
The authors declare no conflict of interest.