Urban Traffic Emissions and Associated Environmental Impacts in India - Novel Combustion Concepts for Sustainable Energy Development - page 397

vehicles in the country grew at a compound annual growth rate (CAGR) of 9.9 %
between 2001 and 2011 (MoS&PI 2014 ). Of these, 32 % are concentrated in 23
metropolitan cities of India. Delhi itself accounts for about 8 % of the total regis-
tered vehicles and has more registered vehicles than those in Mumbai, Kolkata, and
Chennai taken together (TERI 2001b ). The rapid increase in the number of vehicles
has signi cantly raised the emission loads of various air pollutants. Pachauri and

Sridharan ( 1998 ) found that total pollution load from transportation sector in India
has increased 68 times from 1947 (150 Tg) to 1997 (10,300 Tg). During this period,
CO emission had the largest share (43 %) of the total pollutants from transport
sector, followed by NO x (30 %), HC (20 %), SPM (5 %), and SO 2 (2 %). According
to CPCB ( 2000 ), twelve major metropolitan cities in India produce 0.35 Gg of NO x ,
1.91 Gg of CO, and 0.67 Gg of VOC annually from vehicular emissions alone. The
quantum of vehicular pollutants emitted has been found highest in Delhi followed
by Mumbai, Bangalore, Kolkata, and Ahmadabad (TERI 2001a ).
Several studies have shown that vehicular emissions are a major culprit for the
air quality degradation in Indian cities (Gurjar et al. 2004 , 2010a ; Nagpure et al.
2011 , 2014 ; Kumar et al. 2011 ; Nagpure and Gurjar, 2012 ; Nagpure et al. 2013 ;
Babaee et al. 2014 ). Urban population, number of cities, and urban area are growing
at faster rate in the country resulting in the increasing demand of energy, goods, and
services. With these demands, both private and public sector transportation systems
are expanding rapidly in the country, even the current improved technologies in
transportation sector are insuf

cient to counteract this growth in sustainable way.
The future forecast of increasing demands therefore consistently shows the dete-
riorating air quality in the urban areas. This congruence has contributed to urban air
pollution problem directly related to exhaust and non-exhaust motor vehicle
emissions of particulate matter and other hazards pollutants. Because of sources of
these emissions, the public health implications are substantial. Therefore, better
understanding of traf c emissions and associated environmental impacts in India is

needed. Current article presents an overview of urban traf c emissions and asso-

ciated impacts in the Indian context (Gurjar et al. 2004 , 2010a ; Nagpure et al. 2011 ,
2014 ).

2 Vehicular Emission Sources and Pollutants

Figure 1 shows the types of emission source from vehicles. Burning fuel in engine
provides energy to vehicle to move on the road. GHG emissions (e.g., CO 2 ,NO x ) and
most of the pollutants (e.g., CO, HC, PM, benzene, 1 3 butadiene, formaldehyde,

acetaldehyde, total aldehyde, and total PAH) from vehicle are the by-product and this
process is called exhaust emission. In addition to exhaust, vehicle also emits pollu-
tants (e.g., VOCs) from other activities such as fuel evaporation during ri

-

ing and
vehicle operation, and non-exhaust emission (e.g., PM 10, PM 2.5) from break wear,
tire, and road surface wear (Gurjar et al. 2004 , 2010a ; Nagpure et al. 2011 , 2014 ).

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