Transport System

Dhaka, the capital and the mega city of Bangladesh, has a population of about 10 million who use both motorized and non-motorized vehicles for transportation. The city has both private and public transport facilities. However, the majority of the city dwellers and outside commuters depend on public transport system. Bus, minibus, rail and small passenger vehicles operate in different routes within the city. Small passenger vehicles, among others, play a major role in the city transport system. The vehicles are using diesel, gasoline and lube oil as energy.

Bangladesh Government has taken initiatives for reducing air pollution through introducing Compressed Natural Gas (CNG) driven vehicles. The lack of existing infrastructure including CNG filling stations and conversion facilities is a barrier for vehicles to use CNG in place of diesel and gasoline.

At present, only a small fraction of the total vehicles are operating on CNG. There is no doubt that CNG is a cleaner and comparatively environment friendly fuels as far as CO, HC and CO2 emission are concerned. But with the present number of CNG vehicles significant improvement in air quality is not envisaged unless suitable measures are taken to target the private vehicles in Dhaka. Also at this juncture it is not clear what strategy will be best suited in addressing the core issue of vehicular pollution and what price would be paid for reducing the vehicular air pollution load in Dhaka? However, there appears to be no clear road to attain air quality improvement under present circumstances

Recently as in other parts of the world air pollution has received priority among environmental issues in Asia. This problem is acute in dhaka, the capital of Bangladesh and also the hub of commercial activity. The other urban areas like chittagong, khulna, bogra and rajshahi have much lesser health problem related to air pollution.  In the rural areas of Bangladesh, the air pollution problems have not yet become a point of concern. This is due to fewer motorised vehicles and industries there.

With increased rate of urbanisation in the country, the number of vehicles is also increasing rapidly, and contributing to more and more air pollution. The Department of Environment (DOE), and other related organisations, have identified the two-stroke engines used in autorickshaws (baby-taxies), tempos, mini-trucks, and motorcycles as major polluters. At present, there are about 65,000 baby-taxies among them more than 296,000 motor vehicles ply in Dhaka City alone. Moreover, overloaded, poorly maintained and very old trucks and mini-buses are also plying the city streets emitting smokes and gases. In fact about 90% of the vehicles that ply Dhaka's streets daily are faulty, and emit smoke far exceeding the prescribed limit. Diesel vehicles emit black smoke, which contain unburned fine carbon particles.

During July 1999 the Government of Bangladesh (GOB) executed the decision to provide only unleaded gasoline in the country. According to recent measurements between late 1999 and 2000 by BAEC and eastern refinery limited (ERL) the gasoline dispensed at pumps in Bangladesh is now totally free of lead.

The two-stroke engines are now discouraged in Bangladesh because of their pollution hazard. In view of the serious automobile pollution faced in the metropolis, an initiative was taken with World Bank support to introduce big buses in the city and discourage the plying of small automobiles, including baby-taxis. The introduction of air-conditioned city bus service is an outcome of that initiative.

Prior to introduction of unleaded gasoline, BAEC reported that the air that city dwellers breathe on the roads contains lead in concentrations almost ten times above the government safety standard set by the DOE. The air of Dhaka City holds 463 nanograms per cubic meter of lead - the highest in the world. From November 96 to March 97 the lead levels in three different areas of Dhaka City were 123-252 nanograms per cubic meter at Farmgate area and 61 to 76 nanograms per cubic meter in Tejgaon Industrial area.

The lead poisoning produces neuro-developmental disorders in children. About 50 tons of lead is emitted in the Dhaka air annually and the emission reaches its highest level in the dry season from November to January. Lead poisoning has been detected recently in children at the Shishu Bikash Kendro (Child Development Centre) of Dhaka Shishu Hospital. Lead concentrations, measured around 80-micrograms/dl-to180 micrograms/dl in the tested children's blood, is 7-16 times more than the acceptable limit. The safe concentration advocated by the US Centre for Disease Control and Prevention is 10 micrograms/dl. People living in urban slums have a significant rise in mean blood lead levels, compared to those living in urban middle-income or rural areas. The development of lead pollution could also affect the central nervous system, cause renal damage and hypertension. Excessive lead in the blood of children could damage-their brain and kidney. Children are three times more at risk than adults are by exposure to lead poisoning.

In Dhaka city the mean blood lead level of rickshaw pullers is 248 micrograms/dl (range 154-344 micrograms/dl), baby-taxi drivers 287 micrograms/dl, traffic police 272 micrograms/dl (range 152-32 micrograms/dl), tempo assistants 255 micrograms/dl, and petrol pump operators 249 micrograms/dl (range 207-342 micrograms/dl). The mean blood lead level among these risk groups is found to be higher than the acceptable value, with traffic police being the worst affected group. The blood lead levels usually increased with duration of exposure.

Government decisions recently the Ministry of Energy and Mineral Resources (MEMR) has taken important decisions, which are as follows (i) the minimum standard of lubricating oil for two- stroke engine should be APITC or JASOEB and (ii) marketing of straight mineral oil should stop immediately.

In 1985-86 the Bangladesh Petroleum Corporation started a project to use compressed natural gas (CNG) in vehicles instead of gasoline. The primary objective was to reduce vehicular emissions, as combustion of CNG produces less pollution than gasoline. The World Bank donated Taka 225 million to initiate the project. So far data on the number of vehicles converted to CNG from 1985 to 1997 are as follows: 1985-86 converted vehicles 2; 1988-89 converted vehicles 19; 1989-90 converted vehicles 9; 1990-91 converted vehicles 6; 1991-92 converted vehicles 10; 1992-93 converted vehicles 16; 1993-94 converted vehicles 3; 1995-96 converted vehicles 13 and 1996-97 converted vehicles 86. Private sector participation in using CNG for taxicabs is significant. At the beginning of 2002 the Government has started promotional campaign and appropriate push to the owners of autorickshaws to use CNG in order to reduce vehicular emissions.

The Bangladesh atomic energy commission (BAEC) and the Bangladesh Council of Scientific and Industrial Research (BCSIR), in collaboration with the DOE, recently assessed the concentration of lead in the ambient air. The Dhaka Shishu hospital in association with the BAEC also estimated the level of lead in the blood of children of Dhaka City and the possible impact of leaded gasoline on them. The Bangladesh Road Transport Authority (BRTA) is also setting up a vehicle emission monitoring station at Mirpur, Dhaka.

Dhaka Air Quality Context
In Bangladesh urban air pollution is worsening rapidly due to upward trends in vehicle ownership and use, particularly two-stroke engine vehicles. Four pollutants – suspended particulate matter (SPM), carbon monoxide (CO), sulfur dioxide (SO2), and air-borne lead - pose significant air pollution problems, and have major public health impacts. In particular, SPM levels in Dhaka range from 2 to 4 times Bangladeshi standards, but up to 12 times worse than WHO guidelines in the most heavily polluted commercial locations in Dhaka. Ambient SO2 levels are nearly five times national standards in commercial area, and nearly ten times above WHO guidelines.

Air Quality Standards
Table 1 lists air quality standards adopted in Bangladesh, World Health Organization Standards, and National Ambient Air Quality Standards adopted in the US for comparison purposes.

Existing and Proposed Bangladesh Emission Standards
Vehicular emission standards were adopted by the Government of Bangladesh under the Environment Protection Rules of 1997 (Schedule 6, SRO No. 197-Law/97 dt 27.8.97). The standards are as shown in Table 3:

The adopted standards have several serious shortcomings that effectively limit their effectiveness, as follows:

The Hartridge smoke unit measurement for black smoke is not applicable to white smoke emitted by 3-wheeler, two-stroke engines but can only be used for diesel poweredvehicles. Opacity standards can be applied to any vehicle. The absence of a opacity standard for control of two-stroke engine smoke emissions is a serious omission.
• The g/km specification for CO, HC and NOx cannot be practically implementedwithout installation of chassis dynamometers at the inspection stations and are therefore not likely to be implemented.
• The hydrocarbon standard of 180 ppm is extremely low compared to Thailand standards (5,000 ppm for 3-wheelers and 10,000 ppm for motorcycles). Since the standard does not distinguish between vehicle types, age of the vehicle or gross tonnage, the 180 ppm standard would seem to apply to 3-wheelers as well as passenger cars. Recent tests of HC emissions from 3-wheelers indicate that the average emission concentration is about 4,000 ppm.
• The current Bangladesh emission standards do not reference a measurement method or vehicle test cycle so the specifics of vehicle operation applicable to the standards cannot be determined. Vehicle type, weight, age and fuel are also not specified.
As an interim measure, recommended emission standards for passenger cars, diesel buses and trucks are those adopted by Thailand in 1996, and as shown in Table 4.

Lead Pollution: Current Threat

In Dhaka, the biggest threat to public health is the severe lead pollution in its air. According to the scientists of Bangladesh Atomic Energy Commission (BAEC), lead pollution reaches its highest level in the air of Dhaka during the dry season. A team of scientists from the Bangladesh Atomic Energy Commission led by Dr. Khalikuzzaman conducted a series of tests to measure the level of lead pollution in Dhaka. The team has found the lead pollution in Dhaka's air in November-December- January to be 463 nanograms (one nanogram is one billionth of a gram) per cubic meter. In the air of Mexico City, where level of air pollution is considered to be highest in the world, lead pollution is 383 nanograms per cubic meter. Mumbai, the third highest lead polluted city has a lead pollution of 360 nanograms per cubic meter.

The use of leaded petrol is solely responsible for the lead pollution in Dhaka's air. The fine particles of lead spread in the air with the smoke emitted from vehicles, which run on leaded petrol. Lead particles are so thin that the upper part of the human respiratory organs is in no way capable to prevent them. These fine particles enter straight into the lungs and finally mix in the blood stream.

Dr. Khaliquzzaman, principal Scientific Officer of Bangladesh Atomic Energy Commission said that the lead concentration in Dhaka's air varies from monsoon to winter. During the dry season of winter the pollution level rises to 463 nanograms per cubic meter which comes down to 160 nanograms per cubic meter during the monsoon. From February to May, during the moderate rainfall period the level of lead pollution in Dhaka's air again rises to 253 nanograms per cubic meter. But although lead pollution in Dhaka is the highest in the world it is still within the acceptable level recommended by the World Heatth Organization (WHO). According to the WHO standard lead pollution in the air exceeding 1.5 micrograms (1500 nanograms) per cubic meter should be considered dangerous.

The symptoms of lead pollution in the body are weakness, constipation, terrible convulsion and pain in the lower stomach, anemia and occasional psychological disorder and paralysis. Children are the worst victims of the possible lead pollution in an area. Lead slows down the physical and mental growth of a child and reduces the working capacity of the Red Blood Corpuscles (RBC). As a result, their IQ decreases and in many cases they become mentally retarded.

A child absorbs lead 4 times higher than an adult does. It harms the brain and the sensitive nervous system most. That is why children under 6 years exposed to lead pollution suffer most.

Fuel Quality

Fuel quality and vehicle technology are intimately linked and have a combined effect on emission levels. In the global effort for harmonization of fuel quality issues, a World Wide Fuel Charter (WWFC) was released in April 2000. The WWFC classifies gasoline and diesel into four categories depending on the specific need, status of fuel quality program and air quality of various countries. After considerable study, the UTEIS team has recommended that Bangladesh adopt WWFC Category II gasoline specifications, and fuel quality as shown in Table 2.

Reduction of Sulfur in Diesel

At present Bangladesh has a standard for sulfur content in diesel for 0.5% m/m, which is quite high. The proposed limit is to bring down the sulfur content to 0.25%. The reduction in sulfur content from diesel is most important option for achieving air toxic pollutant emissions from diesel vehicles. The sulfur reduction has direct benefit of reducing SOx to a large extent and reducing PM to some extent from diesel exhaust.

Fuel Cost Differences (Gasoline, Diesel and CNG)
Worldwide, the retail price of diesel is typically lower than that of gasoline, as a result of differential taxation. The trend is particularly pronounced in South Asia. In Bangladesh, for example, the retail price of gasoline was almost double that diesel in 1999. The price differential, together with the low profit margin fixed by the government for the sale of gasoline, has led to the adulteration of gasoline with kerosene and, as an unintended consequence, to higher particulate emissions from vehicles. In Pakistan, where the price difference is even higher, the diesel-gasoline ratio consumed in the transport sector reached 4.5 to 1 in fiscal 1996–97, which is very high compared to international averages. Similar trends have been observed in India, where, as a corrective action, the government recently increased the price of diesel sharply. Large tax differences or, in many cases subsidies (for example in Indonesia) in favor of diesel have adverse environmental implications in developing countries where diesel vehicles are poorly maintained and become large sources of serious health damages caused by particulate emissions. At the same time diesel subsidies have not been very efficient as a social measure in targeting poor populations (users of public transport run by diesel buses).

Introduction of CNG as Alternatives
In Bangladesh, natural gas (NG) is abundantly available. Recent estimates by the US Geological Survey reveals that the total resource reserve of natural gas is about 32 trillion cubic feet (TCF). PetroBangla estimates the recoverable natural gas reserves to be about 12 TCF. The annual consumption of natural gas in year 1998 was about 0.2625 TCF. There are22 gas fields in Bangladesh including recently explored two fields of Bibiyana and Moulavibazar in 1998 and 1999 respectively. The natural gas available in Bangladesh mostly contains methane to the tune of 95-97 percent.

CNG has been used as clean fuel for automobiles in various countries for a long time. Many vehicle owners use CNG as it is cost effective as compared to diesel. In Japan, however, itis used mainly because of its environmental advantages even though CNG costs more than diesel. Natural gas is an environmentally-friendly fuel due to three major reasons.

• First, NG typically contains mostly methane (95-97 % in case of Bangladesh). The emissions from NG vehicle exhaust contain about 20-25 percent less CO2 up to 90 percent less CO, and 75 to 90 percent less non-methane hydrocarbons. Unburned methane is a major emission from CNG vehicle exhaust. Although methane is a greenhouse gas having the greenhouse gas potential of 32 CO2 equivalent, natural gas vehicles on the whole contribute less to greenhouse gas formation as NG contains less carbon as compare to gasoline and other petroleum products. Moreover methane is not a volatile organic compound (VOC) and thus does not react with NOx which otherwise results in formation of ozone and photochemical smog. CNG has 80 percent less ozone generating potential than gasoline.

• Second, the fuel cycle emissions of NG are much less than other vehicle fuels. The refining, processing, conversion, and transportation by road are not required in case of NG. The only energy requirement is for compression to high pressure. This lesser energy requirement results in fewer fuel cycle emissions.

• Third, there are no evaporative emissions from CNG vehicles. Carcinogenic and toxic air pollutants such as 1-3 butadiene are not emitted by NG vehicles.

Other advantages of CNG include; no heavy metal additives necessary to increase knock rating, no losses through vaporization from the tank and/ or while refueling, and no transport by road because natural gas is normally supplied via pipelines.

Bangladesh natural gas does not contain toxic elements such as mercury or arsenic. This has been confirmed by experts from BUET and Petrobangla. Secondary evidence supports this finding also.

CNG vehicles emit more NOx in comparison with gasoline, however de-NOx converters would be able to reduce the NOx emissions to acceptable levels. CNG results in 10-20 percent less power output with existing engines and may pose problem of premature defects of engine components (gas pressure regulators, valves, gaskets, hoses, monometers, etc). Storage cylinders are heavy which add load on vehicle, space requirement is also large for placing these cylinders. Operation of vehicle may be restricted to shorter distance ranges due to unavailability of CNG stations widely.

At this time the consumption of NG in transport sector particularly as automotive fuel is negligible. However, there is a growing demand for conversion of cars and baby taxis to CNG vehicles, with the condition that sufficient number of CNG filling stations are available. Estimated demand of CNG for car for the year 2008 would be 136,000 m3/day and 226,000 m3/day with conversion of 30 and 50 percent of cars respectively. The immediate demand could be of 80,000 and 135,000 m3/day for similar percentage of cars to be converted to CNG.

The present government has also formulated some action plan discussing with the various stakeholders of the society to control vehicular air pollution and improvement of transport system. For example, The Environment Conservation Rules 1997 has been amended and under this amended rules, use of Catalytic Converter and Diesel Particulate Filter for Petrol and Diesel driven vehicles respectively has been made mandatory. Ministry of Communication has taken a step to a total ban on plying of two strokes three wheelers in Dhaka City from January 2003. Moreover, a ban has been imposed on plying in Dhaka City from 1 January 2002 of Bus, Minibus, Microbus, Taxi older than 20 years and Truck, Mini truck, Tank lorry, Van older than 25 years. Moreover, introduction of four-stroke CNG run-auto-richshaws, use of low sulfur content fuel prove the noble intention of the government. Please follow the link to view the Major Decisions taken on Vehicular Emissions by the Government.


Source:

1. URBAN TRANSPORT AND ENVIRONMENT IMPROVEMENT STUDY: FINAL REPORT, BRTC-GOB          

2. Banglapedia