Abstract:
Dhaka, the capital of Bangladesh, is the center of all administrative,
economic and cultural activities. The city has now a population of more than
12 million in the area of 2,000 sq. km. According to Bangladesh Road
Transport Authority (BRTA), there are around 4 lakh-motorized vehicles
operating in Dhaka city. Vehicle emission in Dhaka city is Increasing day by
day with the increase of motor vehicle thus polluting the environment. It has
been recognized that motor vehicles play the leading role in the problem of
urban air pollution.
Road transportation has most adversely affected the air quality in Dhaka City.
The existing fleet of 4 lakh molor vehicles in Dhaka contributes nearly 70% of
the total air pollution load. To improve the air quality in Dhaka various
measures viz. Improvement of engine technology, fuel quality, use of exhaust
treatment devices, use of Compressed Natural Gas (CNG) etc. have been
adopted in the recent years by the Government.
The CNG vehicles have been assumed as non-polluting vehicles, hence no
certification was required until recently for tail-pipe emissions, which
otherwise is mandatory for all other vehicles. To understand how these inuse
CNG vehicles compared against their petrol-driven counterparts, this
study is undertaken in Dhaka city.
The tailpipe CO and HC emission characteristics of CNG vehicles were
analyzed and compared against the emiSSion characteristics of similar
vehicle categories earlier using petrol as fuel. The emission levels were
compared against the legislated tailpipe CO emission standards of 4.5% and
3% (by volume) for both the CNG three and four wheelers. The comparison
has revealed notable reduction in CO and HC emissions from CNG driven
vehicles, especially from three wheelers. In this regard, more research is
necessary to find out the right way to reduce the vehicle emission to the
minimum level. As Ihe number of CNG vehicles and CNG conversion
workshops are increasing day-by-day, there is a pressing need to initiate the
process of certification and generation of database for CNG driven vehicles,
It will in one hand, provide the information regarding effectiveness of CNG as
transport fuel on the other hand, it will help to improve the CNG technology
continuously 10reduce vehicle emission,
