Urban Traffic Emissions and Associated Environmental Impacts in India - Novel Combustion Concepts for Sustainable Energy Development - page 401

Fig. 5 Comparison of
vehicle population growth,
emission, and ambient
concentration of NOx in
Mumbai during 1996 - 2005.
Source based on TERI ( 2002 ),
CPCB ( 2008 )

NOx Emission Vehicle Population NOx Concentration

1.40 40

35

1.20

30

1.00

25

0.80

20

0.60

15

0.40

10

0.20

5

0.00 0

Year

In recent years, various studies (Gurjar et al. 2010a ; Nagpure et al. 2013 , 2014 )
suggested that transport is the predominant source of NOx because of the increased
number of motor vehicles in Kolkata. Estimated annual emission from transport
increased from 1.82 to 25.55 Gg between years 1970 and 1990. The main vehicular
sources of NOx are diesel-driven trucks and buses. Although diesel-driven vehicles
account for approximately 10 % motor vehicle population of Kolkata, but they are
responsible for almost 90 % of NOx emissions caused by motor vehicle (ESS
2002 ). ADB ( 2005 ) concluded that within the vehicle fleet, buses (53.7 %) are the
principal source of NOx. Sharma et al. ( 2002b ) estimated the NOx emissions from
gasoline consuming vehicles were 0.3 Gg in 1990 1991 and increased to 0.4 Gg in

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1995 1996, while the emission from diesel was 2.6 and 3.2 Gg for the same period.

Another study done by ADB ( 2005 ) estimated that in 2003, the total annual
emission of NOx from mobile source was 93.85 Gg. As per ADB ( 2005 ) study, the
total annual RSPM emission in KMA was 76 Gg during 2003 with major contri-
butions from road dust (61 %) followed by vehicles (21 %). Another study suggests
that 50 % of the total SPM comes from transport sector and 48 % from industries in
Kolkata (Chakraborty and Bhattacharya 2004 ). According to a report published by
WHO and UNEP, due to the high SPM and RSPM levels, Kolkata is placed among
the most polluted cities of the world (Chakraborty and Bhattacharya 2004 ). The
total emission of air pollutants is around 0.71 Gg per day, in which 0.24 Gg is
single-handedly produced by the vehicles (Chakraborti 1993 ) in Kolkata.
According to the West Bengal Pollution Control Board (WBPCB 2006 ), the
presence of high-level particulate matter in the ambient air is a major problem for
the megacity Kolkata. The major sources of air pollution in Kolkata are the
industrial emissions and automobile emissions. While Asian Development Bank
(ADB 2006 ) estimation suggests that for respirable particulate matter (RPM), paved
road dust is the major contributor in megacity Kolkata followed by vehicles and
open burning (Fig. 4 ). As per ADB, in case of NO x , vehicles (74 %) are the major
source of NO x followed by industrial sources (26 %). Ghose et al. ( 2004 ) stated that
approximately 70 % of the total pollution load of the city is contributed by vehicles
in Kolkata.

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