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					Special Feature : Air Pollution ControlTechnologies
                            Special Feature : Air Pollution Control Technologies




                            Air pollution control

                            Technologies in the transport sector

                              Manju Mohan, Renuka Saini and Shweta Bhati




           Automobiles are a major source of air pollution in urban areas. This article explores
           technical and non-technical ways to control this pollution. It examines regulation of
           vehicular emission in relation to fuel characteristics, impact on air quality and stan-
           dards enforcement in various Asian nations. In addition to the various technical and
           non-technical ways, vehicular pollution can also be mitigated by the development
           of an efficient public transport system. The article discusses the cases of two modes
           of public transport systems - Rapid Bus Transit and Metro rail - in Delhi, India. While
           growth in the number of vehicles cannot be contained, the right means can ensure
           that the air we breathe does not damage our health.




                                     Introduction                                   ing. The incidence of other transport-
                                              otorized road vehicles are the        related pollutants (e.g. CO, NOx, SO2

                                     M        primary means of transporting
                                              passengers and freight because
                                     of their versatility, flexibility, and low
                                                                                    and O3) in developing countries also
                                                                                    exceeds international and national
                                                                                    norms. The associated human health
                                     initial cost as compared to other trans-       and welfare costs run into hundreds of
                                     port modes. In all but the poorest de-         millions of dollars and far exceed the
                                     veloping countries, economic growth,           prevention costs.
                                     rising incomes and urbanization are                  With economic prosperity and ur-
                                     contributing to a rapid increase in ve-        banization, there has been an unabat-
                                     hicle ownership and use.                       ed increase in motor vehicles, bring-
                                           Over the last two decades, motor         ing unprecedented mobility to the bur-
        Prof. Manju Mohan            vehicles have emerged as a critical            geoning middle class in many Asian
         Ms.Renuka Saini             source of urban air pollution in much          countries. Although per capita vehicle
         Ms. Shweta Bhati            of the developing world. For example,          ownership in most Asian countries is
  Centre for Atmospheric Sciences    motor vehicles are the largest source          low compared to OECD countries (for
   Indian Institute of Technology    of PM10 emissions in most Asian cities,        example, in China there are about 8
Hauz Khas, New Delhi-110016, India   exceeding the contributions from re-           vehicles per 1,000 persons and in In-
  E-mail: mmohan65@yahoo.com         suspended road dust, heavy fuel oil            dia only 7 vehicles per 1,000 persons
    (Author for correspondence)      and coal combustion, and refuse burn-          compared to 750 vehicles per 1,000



                                                                                  TECH MONITOR      Nov-Dec 2008   15
Special Feature : Air Pollution Control Technologies

persons in the USA), vehicle growth in       ternal combustion engine, commonly           tion timing is governed by timing the
the region has been phenomenal. The          referred to as a diesel engine. This en-     injection of the fuel, and the power
growth of motor vehicles in China has        gine is used for large trucks, buses,        delivered is controlled by the amount
averaged about 11 per cent annually          locomotives and ships.                       of fuel injected in each cycle. The air-
in the last 30 years doubling every 5              The basic principle of the operat-     fuel mixture in a diesel engine is gen-
years, and in India the growth has been      ing cycle of the spark-ignited internal      erally much leaner than that in a spark-
around 7 per cent per year for the past      combustion engine is that a piston           ignition engine.
10 years.                                    moves up and down within a cylinder,
      Common air pollutants in urban         transmitting its motion through a con-       Emissions from vehicles
areas from the transport sector include:     necting rod to a crankshaft, which           Motor vehicle emissions occur during
    Respirable particulate matter from       drives the vehicle. The four strokes of      these various stages of the working of
    smoky diesel vehicles, two-stroke        the spark-ignited internal combustion        the internal combustion engines. Main-
    motorcycles and 3-wheelers, burn-        engine are:                                  ly they can be classified as:
    ing of waste and firewood, en-                Intake - The descending piston              Crankcase emissions. Due to “blow-
    trained road dust, and stationary             draws a mixture of petrol and air in        by” around the piston rings, gases
    industrial sources;                           through the open intake valve.              may escape from the cylinder into
    Carbon monoxide from petrol vehi-             Compression - The rising piston             the crankcase. The largest part of the
    cles and burning of waste and fire-           compresses the fuel-air mixture.            resulting emissions corresponds to
    wood; and                                     Near or at the top of the stroke the        the unburnt air-fuel charge, and only
    Photochemical smog (ozone), pro-              spark plug fires, igniting the mix-         a small part consists of exhaust prod-
    duced by the reaction of volatile             ture.                                       ucts and lube vapour.
    organic compounds and nitrogen                Expansion - The burning mixture             Evaporative emissions. Fuel evap-
                                                  expands, driving the piston down            oration may occur in the tank as well
    oxides in the presence of sunlight.
                                                  and delivering power.                       as in the carburettor. In addition, fuel
Motor vehicle emissions are a major               Exhaust - The exhaust valve opens           vapour is displaced during refuel-
source of nitrogen oxides and volatile            as the piston rises, expelling the          ling. Evaporative losses markedly
organic compounds:                                burned gases from the cylinder.             increase with increasing air temper-
   Sulphur oxides from combustion of         The fuel-air mixture is prepared in the          ature. Besides, they depend on the
   sulphur-containing fuels;                 carburettor. This mixture is character-          fuel volatility.
   Secondary particulate matter formed       ized by its air-fuel ratio, the weight of        Tailpipe emissions: These are emit-
   in the atmosphere by reactions in-        the air per weight of fuel. Ratios below         ted from the vehicle’s exhaust sys-
   volving ozone, sulphur and nitrogen       9 and above 20 are generally not com-            tem. The major pollutants emitted
   oxides and volatile organic com-          bustible. Maximum power is obtained              include Hydrocarbons, Nitrogen
   pounds; and                               at a lower ratio than for minimum fuel           oxides (NOx ), Carbon monoxide
   Known or suspected carcinogens,           consumption. Mixtures with low air-fuel          (CO), Carbon dioxide (CO2), Par-
   such as benzene, 1, 3 butadiene,          ratios are referred to as rich, whereas          ticulates and Sulphur oxides (SOx).
   aldehydes, and polynuclear aro-           those with high ratios are called lean.
   matic hydrocarbons, from motor            During acceleration, when power is           Factors influencing
   vehicle exhaust and other sources.        needed, a richer mixture is required         motor vehicle emissions
                                             than during cruising. The spark during          Vehicle and fuel characteristics
                                             the compression stage propagates                   Engine type and technology -
Motor vehicle emissions -                    unevenly across the cylinder. As a con-            two-stroke, four-stroke; Diesel,
concepts and causes                          sequence of the non-homogeneous                    Otto, Wankel, others; fuel injec-
                                             temperature distribution, the combus-              tion, turbo-charging, type of trans-
The internal combustion engine               tion in an Otto engine is to a consider-           mission system.
With few exceptions, motor vehicles are      able extent incomplete. This is of para-           Exhaust, crankcase, and evap-
equipped with internal combustion en-        mount importance with respect to au-               orative emission control sys-
gines. In such engines, a compressed         tomotive exhaust.                                  tems in place - catalytic convert-
mixture of air and fuel is ignited to pro-         In a diesel engine, air and fuel are         ers, exhaust gas recirculation,
vide the mechanical energy needed to         not mixed prior to being passed into               air injection.
drive the crankshaft. There are two          the cylinder. Air is drawn in through              Engine mechanical condition
common types of internal combustion          the intake valve, and while it is being            and adequacy of maintenance.
engines in use. The most common is           compressed to a high temperature, fuel             Air conditioning, trailer towing
the Otto engine, which is a four-stroke-     is injected into the chamber as a spray            and other vehicle appurtenanc-
cycle, spark-ignited internal combus-        under high pressure in precise quanti-             es.
tion engine, used primarily for passen-      ties. As the piston nears the top posi-            Deterioration characteristics of
ger cars and light-duty trucks. The sec-     tion, the high temperature and pres-               emission control equipment.
ond most common is the four- and two-        sure of compression cause ignition of              Deployment and effectiveness
stroke-cycle, compression-ignition in-       the fuel without the aid of a spark. Igni-         of inspection/maintenance (I/M)



16     TECH MONITOR          Nov-Dec 2008
                                                                                            Special Feature : Air Pollution Control Technologies

          and anti-tampering (ATP) pro-           Figure 1: Motorization trends in major Asian countries
          gramme.
      Fleet characteristics
          Vehicle mix (number and types                                                1970        1975          1980    1985     1990        1995      2000   2005
                                                                                     500
          of vehicles in use) and utiliza-
          tion (km per vehicle per year);
          Age profile of vehicle fleet; and                                          400
          Traffic mix and choice of mode for
          passenger/goods movements.                                                 300
      Operating characteristics
          Altitude, temperature, humidity
          (for NOx emissions);                                                       200

          Vehicle use patterns: number
          and lengths of trips, number of                                            100
          cold starts, speed, loading, ag-
          gressive driving behaviour; and
                                                                              80
          Degree of traffic congestion,
                                                 Passenger cars+motorcycles




          capacity and quality of road in-
                                                    per 1,000 population




          frastructure, and traffic control                                   60
          systems.
      Fuel adulteration                                                       40
Financial incentives arising from differ-
ential taxes are generally the primary
                                                                              20
cause of fuel adulteration. In South Asia,
petrol carries a much higher tax than
diesel, which, in turn, is taxed more than                                    0
kerosene. Industrial solvents and recy-                                       1970   1975        1980       1985        1990     1995       2000       2005
cled lubricants are other materials with                                                      Cambodia                          PRC
                                                                                              Hong Kong, China                  Republic of Korea
little or no tax. Adulteration of petrol and                                                  India                             Singapore
                                                                                              Indonesia                         Sri Lanka
diesel takes place primarily due to the                                                       Japan                             Taipei, China
                                                                                              Malaysia                          Thailand
significant price difference between                                                          Nepal                             United Kingdom
these products and the adulterant. Petrol                                                     Pakistan
                                                                                              The Philippines
                                                                                                                                Viet Nam

may also be adulterated with kerosene
and some petrol boiling range solvent                                                                                                               Source ADB, 2002
like toluene, xylene and other aromat-
ics. Diesel is also adulterated with high      concentration of various pollutants in                                     engine design, combustion conditions,
sulphur content kerosene.                      some Asian cities. While considering both                                  and catalytic after treatment. Some of
       Adulteration of fuel can cause in-      Figures 1 and 2 together, it can be seen                                   the engine and combustion variables
creased tailpipe emissions of hydrocar-        that countries with steep growth in vehi-                                  that affect emissions are air-fuel ratio,
bons (HC), carbon monoxide (CO), ox-           cle count from 2000 onwards such as                                        ignition timing, turbulence in the com-
ides of nitrogen (NOx) and particulate         Republic of Korea (Busan, Seoul), Chi-                                     bustion chamber, and exhaust gas re-
matter (PM). Adulteration of fuels can         na (Hong Kong, Shanghai, Taipei), Indo-                                    circulation. Of these, the most impor-
also cause emissions of air toxins like        nesia (Jakarta) and India also have high-                                  tant is the air-fuel ratio.
benzene and polyaromatic hydrocar-             er than prescribed standards of Nitrogen
bons (PAHs), both known carcinogens.           Oxides and Total Suspended Particulate                                     Air-fuel ratio
                                               (TSP) matter.                                                              The ratio of air to fuel in the combustible
Air quality and the transport sector                A similar observation is displayed                                    mixture is a key design parameter for
Levels of nitrogen dioxide, carbon mon-        in Figure 3 for Delhi, where an increas-                                   spark-ignition engines. An air-fuel mix-
oxide, hydrocarbons and particulates are       ing vehicle count over the years corre-                                    ture that has exactly enough air to burn
highest in towns and cities, where there       sponds to an increasing level of ambi-                                     the fuel, with neither air nor fuel left over,
is more traffic. Road transport is also the    ent nitrogen oxides.                                                       is stoichiometric, and has a normalized
main cause of ozone. Ozone does not                                                                                       air-fuel ratio (ë) of 1.0. Mixtures with more
come directly from vehicles or factories                                                                                  air than fuel are lean, with ë higher than
                                               Vehicle technology
but is created by chemical reactions be-                                                                                  1.0; those with more fuel are rich, with ë
tween other nitrogen oxides and hydro-         for controlling emissions                                                  less than 1.0. A mixture with ë of 1.5 has
carbons.                                                                                                                  50 per cent more air than needed to burn
     Figure 1 shows the motorization           Petrol-fuelled vehicles                                                    all the fuel. Engines using lean mixtures
trends in some major Asian countries,          Emissions from spark-ignition engines                                      are more efficient than those using sto-
while Figure 2 depicts annual average          can be reduced through changes in                                          ichiometric mixtures. There are a num-



                                                                                                                        TECH MONITOR                Nov-Dec 2008   17
Special Feature : Air Pollution Control Technologies

   Figure 2: Average annual air pollution concentrations (2000 - 2004) in selected Asian cities

  400


  350


  300


  250


  200


  150


  100


    50


      0
                        g                          a       i             n       ng                  du     at
                                                                                                              a                  i         i     l         ai         e        a         na
            ok      ijin      sa
                                n        bo      ak      no            in                   ta                     ila         ba        lh    ou        gh         or       ay        hi     ky
                                                                                                                                                                                                o
          gk                            m
                                               Dh      Ha
                                                                      M        Ko        ar        an     lk     an                    De    Se        an         ap       ab        ,C
        an        Be        Bu       olo                           hi       ng        ak         hm     Ko      M            um
                                                                                                                                     w                h         ng       ur        el       To
                                                                  C
       B                            C                           o          o        J
                                                                                              Ka
                                                                                                t                           M      Ne                S        Si        S         p
                                                               H          H                                                                                                     Ta
                  TSP Limit = 60-90 μg/m3 (WHO, 1979)                          TSP                 SO2 Limit = 50 μg/m3 (WHO, 1999)                           SO2

                                                                               PM10                                                                           NO2
                  PM10 Limit = 20 μg/m3 (WHO, 2005)                                                NO2 Limit = 40 μg/m3 (WHO, 1999)



                                                                                                                                                                      Source: CAI, 2005

   Figure 3: Annual ambient NO2 levels in Delhi, India                                                                                      air-fuel mixture going into the engine
                                                                                                                                            to maintain stoichiometry. In addition
                                    Res. areas                            NAAQS                                                             to the air-fuel ratio, computer systems
                                    No. of vehicles                                                                                         control features that were controlled by
                                                                                                                                            vacuum switches or other devices in
                  70                                                                                              6                         earlier emission control systems. These
                  60                                                                                                                        include spark timing, exhaust gas re-
                                                                                                                  5
                                                                                                                                            circulation, idle speed, air injection sys-
                                                                                                                         No. of vehicles
  Concentration




                  50                                                                                                                        tems, and evaporative canister purg-
                                                                                                                          (in millions)




                                                                                                                  4
    (μg/m3)




                  40                                                                                                                        ing. The stringent air-fuel ratio require-
                                                                                                                  3                         ments of three-way catalysts made
                  30                                                                                                                        advanced control systems necessary.
                                                                                                                  2                         But the precision and flexibility of the
                  20
                                                                                                                                            electronic control system can reduce
                  10                                                                                              1
                                                                                                                                            emissions even in the absence of a
                   0                                                                                              0                         catalytic converter. Many control sys-
                                                                                                                                            tems can self-diagnose engine and
                         95 996 997 998 999 00 001 002 003 004 005 006                                                                      control system problems. The ability to
                    19     1   1 1 1 20 2 2           2 2     2   2                                                                         warn the driver of a malfunction and
                                                                Year                                                                        assist the mechanic in its diagnosis can
                                                                                                                                            improve maintenance quality. Self-diag-
                                                                                Source: CPCB Report, 2006-07
                                                                                                                                            nostic capabilities are becoming in-
ber of reasons for this, including less                               Electronic control systems                                            creasingly sophisticated and important
heat loss, higher compression ratios                                  Electronic control technology for sto-                                as engine control systems become
(lean mixtures knock less readily), low-                              ichiometric engines using three-way                                   more complex. Computer-controlled
er throttling losses at part load, and                                catalysts has been extensively devel-                                 engine systems are also more resistant
favourable thermodynamic properties in                                oped. These systems measure the air-                                  to tampering and maladjustment than
burnt gases.                                                          fuel ratio in the exhaust and adjust the                              mechanical controls. The tendency for



18           TECH MONITOR                     Nov-Dec 2008
                                                                   Special Feature : Air Pollution Control Technologies

   Figure 4: Catalytic converter                                                                nitrogen oxides by cooling the com-
                                                                                                pressed-charge air with aftercoolers;
                                                                                                Further reducing nitrogen oxides to
                                                                                                meet regulatory targets by retard-
                                                                                                ing fuel injection timing over most
                                                                                                of the speed–load range. A flexible
                                                                                                timing system minimizes the ad-
                                                                                                verse effects of retarded timing on
                                                                                                smoke, starting, and light-load hy-
                                                                                                drocarbon emissions;
                                                                                                Further reducing nitrogen oxides in
                                                                                                light-duty vehicles by recirculating
                                                                                                exhaust gas under light-load con-
                                                                                                ditions;
                                                                                                Reducing the PM increase result-
                                                                                                ing from retarded timing by increas-
                                                                                                ing the fuel injection pressure and
                                                                                                injection rate;
                                                                                                Improving air utilization (and reduc-
                                                                                                ing hydrocarbon and PM emis-
                                                                                                sions) by minimizing parasitic vol-
                                                                                                umes in the combustion chamber–
                                                                                                such as the clearance between the
                                                                                                piston and the cylinder head and
                                                                                                the clearance between the piston
                                                                                                and the walls of the cylinder;
emissions to increase over time is thus      retted vehicles, the carburettor bowl)
                                                                                                Optimizing in-cylinder air motion
reduced in computer-controlled vehicles.     to the atmosphere through a canister               through changes in combustion
                                             of activated charcoal. Hydrocarbon                 chamber geometry and intake air
Catalytic converters                         vapours are adsorbed by the charcoal,              swirl to provide adequate mixing at
The catalytic converter (Figure 4) is one    so little vapour escapes to the air. The           low speeds (to minimize smoke
of the most effective emission control       charcoal canister is regenerated or                and PM) without over-rapid mixing
devices available. The catalytic con-        “purged” by drawing air through it into            at high speeds (which would in-
verter processes exhaust to remove           the intake manifold when the engine is             crease hydrocarbons, nitrogen ox-
pollutants, achieving considerably low-      running. Adsorbed hydrocarbons are                 ides and fuel consumption); and
er emissions than is possible with in-       stripped from the charcoal and burned              Controlling smoke and PM emis-
cylinder techniques. The catalytic con-      in the engine.                                     sions in full-power operation and
verter comprises a ceramic support, a                                                           transient accelerations by improv-
washcoat (usually aluminum oxide) to         Diesel-fuelled vehicles                            ing the governor curve shape and
provide a very large surface area and        The engine variables with the greatest             limiting transient smoke (frequent-
a surface layer of precious metals (plat-    effect on diesel emission rates are the            ly through electronic governor con-
inum, rhodium, and palladium are most        combustion chamber design, air-fuel                trols).
commonly used) to perform the cata-          ratio, rate of air-fuel mixing, fuel injec-
lyst function. Two types of catalytic con-   tion timing, compression ratio, and the         In-use vehicles
verters are commonly used in automo-         temperature and composition of the              Inspection and maintenance (I/M) mea-
tive engines: oxidation (two-way) cat-       charge in the cylinder. A typical ap-           sures to control emissions from in-use
alysts control hydrocarbon and carbon        proach to reducing diesel emissions             vehicles are an essential complement
monoxide emissions and oxidation–            includes the following major elements:          to emission standards for new vehicles.
reduction (three-way) catalysts control          Reducing parasitic hydrocarbon              I/M programmes ensure that the bene-
hydrocarbons, carbon monoxide and                and PM emissions (those not direct-         fits of new-vehicle control technologies
nitrogen oxides. A new type of catalyt-          ly related to the combustion process)       are not lost through poor maintenance
ic converter is the lean nitrogen-oxide          by minimizing injection nozzle sac          and tampering with emission controls.
catalyst, which reduces nitrogen oxide           volume and oil consumption;                       Inspection and maintenance of
emissions in lean conditions, where a            Reducing PM emissions and im-               high-technology, computer-controlled
three-way catalyst is ineffective.               proving fuel efficiency and power           vehicles can be enhanced substantially
                                                 output through turbocharging and            with on-board diagnostic systems. For
Evaporative emissions and control                by refining the match between the           diesel vehicles, smoke opacity mea-
Evaporative emissions are controlled             turbocharger and the engine;                surements in free acceleration are the
by venting the fuel tank (and, in carbu-         Reducing emissions of PM and                most common inspection method. Opac-



                                                                                           TECH MONITOR       Nov-Dec 2008    19
Special Feature : Air Pollution Control Technologies

   Figure 5: Regular inspection and maintenance ensures reduced emissions




ity measurements can also be used to        gy availability and accessibility in that           emission norms for CNG and
control white smoke emissions from          region. Normally emissions standards                LPG vehicles.
two-stroke motorcycles.                     are prescribed in terms of European          2003 - Bharat stage II (equivalent to
     Inspection and maintenance pro-        emission standards (Euro) and are                   Euro II) norms for 11 major cities.
grammes help identify equipment de-         progressively introduced with increas-       2005 - Bharat stage III (equivalent to
fects and failures covered by vehicle       ingly stringent standards. Table 1 lists            Euro III) norms for 11 major cities.
warranty schemes. These programmes          the enforcement scenario in some             2010 - Bharat stage III emission norms
also discourage tampering with emis-        major Asian countries.                              for 4-wheelers for the entire
sion controls or misfuelling; the threat          In India, the first emission regula-          country, and Bharat stage IV
of failing inspection is considered a       tions were idle emission limits, which              (equivalent to Euro IV) for 11
strong deterrent. Without effective I/M     became effective in 1989. These idle                major cities.
programmes, compliance with stan-           emission regulations were soon re-
dards is significantly weakened.            placed by mass emission limits for both
                                                                                         Recommendations and
                                            petrol (1991) and diesel (1992) vehi-
                                            cles, which were gradually tightened         suggestions for mitigating
Fuel modifications                                                                       vehicular pollution
                                            during the 1990’s. Since the year 2000,
A major advantage of fuel modifica-
                                            India started adopting European emis-
tions for emissions control is that they
                                            sion and fuel regulations for four-wheeled   Pollution control technology
often take effect quickly and begin re-
                                            light-duty and for heavy-duty.               For petrol vehicles, “three-way” cata-
ducing pollutant emissions immedi-
                                                  On 6 October 2003, a National Auto     lysts, precise engine and fuel controls,
ately, whereas vehicle emission con-
                                            Fuel Policy was announced, which en-         and evaporative emission controls have
trols generally must be phased in with
                                            visaged a phased programme for intro-        been quite successful. More advanced
turnover in a vehicle fleet. Another ad-
                                            ducing Euro 2 - 4 emission and fuel reg-     versions of these technologies are in
vantage of fuel modifications is that       ulations by 2010. The implementation         some cars and can reduce smog-form-
they can be targeted geographically         schedule of EU emission standards in         ing emissions from new vehicles by a
or seasonally by requiring the more         India is summarized below:                   factor of ten. For diesel vehicles, “two-
expensive “clean” fuels only in highly
                                                                                         way” catalysts and engine controls have
polluted areas or during seasons with                                                    been able to reduce hydrocarbon and
a high incidence of elevated pollution      Overview
                                            1991 - Idle CO limits for petrol vehicles    carbon monoxide emissions, but nitro-
episodes. In addition, fuel modifica-                                                    gen oxide and toxic particulate-matter
tions are usually easier to enforce,               and free acceleration smoke for
                                                   diesel vehicles, mass emission        emissions remain very high.
since fuel refining and distribution sys-
                                                   norms for petrol vehicles.
tems are highly centralized. Possible
                                            1992 - Mass emission norms for die-          Burning less fuel
further changes to reduce emissions
                                                   sel vehicles.                         The key to burning less fuel is making
from petrol include reduced volatility,
                                            1996 - Revision of mass emission             cars and trucks more efficient and put-
increased oxygen content, reduced
                                                   norms for petrol and diesel ve-       ting that efficiency to work in improving
aromatics and more widespread use
                                                   hicles, mandatory fitment of          fuel economy. This includes more effi-
of detergent additives. Conventional
                                                   catalytic converter for cars in       cient engines and transmissions, im-
diesel fuel also can be improved by
                                                   metros on unleaded petrol.            proved aerodynamics, better tyres and
reducing the sulphur and aromatic
                                            1998 - Cold start norms introduced.          high strength steel and aluminum. More
content and by using detergent addi-
                                            2000 - India 2000 (equivalent to Euro        advanced technologies, such as hy-
tives.
                                                   I) norms, modified IDC (Indian        brid-electric vehicles that use a petrol
                                                   driving cycle), Bharat stage II       engine and an electric motor plus a
Emission standards                                 norms for Delhi.                      battery, can cut fuel use even further.
Emission standards vary from country        2001 - Bharat stage II (equivalent to        These technologies carry with them
to country depending on the technolo-              Euro II) norms for all metros,        additional costs.



20     TECH MONITOR         Nov-Dec 2008
                                                                  Special Feature : Air Pollution Control Technologies

Zero-emission vehicles                          Table 1: Institutionalizing fuel quality standards
Eliminating emissions from the tailpipe
goes even further to cut down on harm-          Country         Current status                      Future directions
ful air pollutants. Hydrogen fuel-cell       Bangladesh Euro 1 under discus- No dialogue or plans to move beyond
and electric vehicles move away from                    sion                 Euro 1
burning fuel and use electrochemical
                                             Cambodia        No formal standards, No road-map in place
processes instead to produce the en-
                                                             still leaded
ergy needed to drive a car down the
road. Fuel-cell vehicles run on elec-        China           Euro 3 - Beijing and 11th Five Year Plan laying out road-
tricity that is produced directly from the                   Shanghai Euro 2 - Rest map for Euro 3 and Euro 4 for entire country
reaction of hydrogen and oxygen. The                         of the country
only byproduct is water - which is why       Hong Kong Euro 4 in place                   ULSD and Euro 5 (diesel) under consid-
fuel-cell cars and trucks are called
                                             SAR (China)                                 eration for 2007
zero-emission vehicles. Electric vehi-
cles store energy in an onboard bat-         Indonesia       Euro 2 (?)                  Euro 3 gasoline by 2006 & Euro 3 diesel
tery, emitting nothing from the tailpipe.                                                after 2010
                                             Japan           Euro 4 Equipment Ultra-low sulphur gasoline and diesel
Cleaner fuels                                                (S 50 ppm)       2007
The petrol and diesel fuels in use to-
                                             Republic of                                 Ultra-low sulphur gasoline and diesel
day contain significant amounts of sul-
                                             Korea                                       by 2007?
phur and other compounds that make
it harder for existing control technolo-     Malaysia        Euro 2 by 2005              Euro 4 by 2009-2010
gy to keep vehicles clean. Removing          Nepal           Euro 1; still partly No structured discussion on how to move
the sulphur from the fuel and cutting
                                                             leaded               ahead
down on the amount of light hydrocar-
bons helps pollution-control technolo-       Philippines     Euro 1; 500 ppm sul- Euro 2 mid 2005. Initial discussions on
gy to work better and cuts down on                           phur diesel          Euro 4 by 2010
evaporative and refuelling emissions.        Singapore       Euro 2 in place             Euro 4 diesel in 2006, no plans for petrol
     Further large-scale reductions of
other tailpipe pollution and CO2 can be      Sri Lanka       Euro 1 in place             No roadmap in place
accomplished with a shift away from          Thailand        Euro 3 petrol and Euro Euro 4 2006 with discussion ongoing on
conventional fuels. Alternative fuels                        2 for diesel           ULSD in some locations
such as natural gas, methanol, etha-
nol, and hydrogen can deliver benefits       Viet Nam        Euro 3 in 2009 an- Euro 2 in 2007 and Euro 4 in 2010 under
to the environment while helping to                          nounced and under discussion and tentatively scheduled for
move the world away from its depen-                          discussion         July 2005
dence on oil. All of these fuels inher-                                      Source: Clean Air Initiative-Asia, 2005, Brussels
ently burn cleaner than diesel and
petrol and have lower carbon content -                                                     Asia’s cities, public transport vehicles
                                                reduces vehicular emissions. How-
resulting in less CO2. Most of these fu-                                                   operating on fixed routes carry the
                                                ever, this also calls for dedicated
els are also more easily made from
                                                cyclist lanes on roads.                    majority of public transport trips.
renewable resources, and fuels such
                                                Driving moderately and avoiding            Policies for public transport to improve
as natural gas and methanol help pro-
                                                frequent stopping and starting.            air quality can either consist of activities
vide a bridge to producing hydrogen
                                                Keeping tyres properly inflated.           that clean the vehicles directly (e.g.
for fuel-cell vehicles.
                                                During start-up, a car’s engine burns      engine upgrades, use of alternative
                                                extra petrol. However, letting an en-      fuels) or can consist of activities that
Personal contributions                                                                     seek to influence modal shift (i.e.
                                                gine idle for more than a minute
How we drive and how we take care of                                                       increase switching to public transport).
                                                burns more fuel than turning off the
our vehicles affect fuel economy and                                                       An example of the use of alternative
pollution emissions. The following are          engine and restarting it.
                                                                                           fuel has been witnessed in Delhi, India,
several ways people can reduce the              During warm periods with strong
                                                                                           where the use of Compressed Natural
harmful environmental impact of cars:           sunlight, parking in the shade keeps
                                                                                           Gas (CNG) was made compulsory for
    Driving as little as possible is the        a car cooler and can minimize the          all public transport vehicles post year
    best way to reduce the harmful en-          evaporation of fuel.                       2000. Similarly, the introduction of a
    vironmental impact of transportation                                                   metro rail system and a Bus Rapid Tran-
    needs. Car-pooling, mass transit         Efficient public transport                    sit system (in Delhi) can be considered
    and walking are ways to limit the        and urban planning                            as an initiative for bringing about a
    number of miles we drive. Also, cy-      The role of public transport varies wide-     change in transport means by people
    cling for travelling shorter distances   ly in Asian cities. However, in most          in general.



                                                                                         TECH MONITOR         Nov-Dec 2008     21
Special Feature : Air Pollution Control Technologies

  Figure 6: Adopting cycling requires dedicated lanes on road                           Maintaining loyalty to public trans-
                                                                                  port or attracting car and motorcycle driv-
                                                                                  ers to switch to public transport is not
                                                                                  easy in view of the status and conve-
                                                                                  nience private vehicle usage confers.
                                                                                  But high quality and fast and accessi-
                                                                                  ble public transport services, whether
                                                                                  by rail or bus, combined with other mea-
                                                                                  sures, such as road pricing and parking
                                                                                  restraints, have proven quite success-
                                                                                  ful in attracting car drivers, especially
                                                                                  when the road system is congested.

                                                                                  Delhi Metro
                                                                                  In developed countries, planning for
                                                                                  mass transit systems such as the Metro
  Figure 7: Implementing and adopting Public Transport is the need of hour
                                                                                  Rail starts when the city population size
                                                                                  exceeds 1 million; the system is in po-
                                                                                  sition by the time the city population is
                                                                                  2 to 3 million and once the population
                                                                                  exceeds 4 million or so, planned ex-
                                                                                  tensions to the Mass Rapid Transit Sys-
                                                                                  tems are vigorously taken up. In devel-
                                                                                  oping countries like India, a Metro Rail
                                                                                  has been proposed for all cities with
                                                                                  more than five million population to
                                                                                  start with, thereafter extending to cities
                                                                                  with a population of more than three
                                                                                  million.
                                                                                       Delhi’s first metro rail system be-
                                                                                  came a huge success when it carried
                                                                                  over 1.2 million passengers on its first
                                                                                  day, 25 December 2002. It is the first
                                                                                  metro system in the world to obtain ISO
                                                                                  14001 certification for environment-
                                                                                  friendly construction and operations at
  Figure 8: Delhi Metro Rail                                                      the construction stage itself, and the
                                                                                  second after the New York Metro to
                                                                                  achieve this standard. The benefits of
                                                                                  this project are manifold as the Metro
                                                                                  carries the same amount of traffic as
                                                                                  nine lanes of buses or 33 lanes of pri-
                                                                                  vate metro cars either way.

                                                                                  Bus Rapid Transit (BRT)
                                                                                  The Bus Rapid Transit (BRT), also
                                                                                  known as the High Capacity Bus Sys-
                                                                                  tem, is one of the cost-effective mech-
                                                                                  anisms for cities to rapidly develop a
                                                                                  public transport system. BRT is an ef-
                                                                                  fective option compared to other pub-
                                                                                  lic transport systems, mainly due to low
                                                                                  capital requirement, low infrastructure
     Improvements to public transport    be implemented in an environment         costs, ability to operate without subsi-
proposed to reduce emissions, or other   where the operations are efficient and   dies and low gestation period. It can be
service quality enhancements should      financially sustainable.                 easily adapted to a range of city condi-



22    TECH MONITOR        Nov-Dec 2008
                                                                    Special Feature : Air Pollution Control Technologies

tions. Various versions of BRT are in             Figure 9: Overhead bridge for passengers in a Transmileneo (Bogota)
existence in Brazil (Curitiba), Columbia                    Busway station (left) and a Busway station in Brisbane (right)
(Bogota), USA (Miami, California), UK
(London, West Sussex), and Australia
(Brisbane). To meet the growing de-
mand, the Government of the National
Capital Territory of Delhi decided to
build six BRT Corridors in Delhi, be-
sides expanding the Metro rail in Del-
hi, by 2010.
      The first pilot stretch of BRT has
met with mixed responses. While pri-
vate vehicle owners complain about             Conclusions                                       in Delhi, Delhi Integrated Multi Mod-
lack of space availability on road, bus        Technical emission control measures               al Transit System Ltd. (DIMTS)”, http:/
commuters feel uncomfortable with the          do not, by themselves, constitute an              /www.dimts.in/road.html.
location of bus stops in the middle of         emission control strategy, nor are they       5. “Delhi Metro Receives ISO 14001
the road. However, people also feel that       sufficient to guarantee environmental-            for Eco-Friendly Systems”, Report,
the BRT is a huge improvement for              ly acceptable outcomes over the long              Date: 2003, USAID India, http://www
buses, giving them dedicated space to          run. Such measures can, however, re-              .usaid.gov/in/about_usaid/success
move on the road and thereby reduc-            duce pollutant emissions per vehicle-             _stories/metro_eco.htm.
ing their travel time to a great extent.       kilometre travelled more than in-use          6. Encyclopedia of Environmental
      Nonetheless, it goes without say-        uncontrolled vehicles.                            Control Technology, Paul N. Cher-
                                                     Although technical measures                 eminisoff, Volume 2, Gulf Publish-
ing that public transport projects like
                                               alone are insufficient to ensure the              ing, Houston, 1989.
BRT are the need of the hour, provided
                                               desired reduction of urban air pollu-         7. “For a Breath of Fresh Air: Ten Years
they are implemented in a way com-
                                               tion, they are an indispensable com-              of Progress and Challenges in Ur-
prehensible to the common man.
                                               ponent of any cost-effective strategy for         ban Air Quality Management in In-
      According to Delhi Integrated Multi
                                               limiting vehicular emissions. Employed            dia 1993-2002”, Environment and
Modal Transit System Ltd. (DIMTS), the
                                               as part of an integrated transport and            Social Development Unit, South
correct measure to consider is not the
                                               environmental programme, these mea-               Asia Region, The World Bank.
number of vehicles but the number of
                                               sures can buy the time necessary to           8. “From Busway to BRT, The City Fix”,
people.
                                               bring about the needed behavioural                July 14, 2008, http://thecityfix.com/
      Buses move far greater numbers
                                               changes in transport demand and the               from-busway-to-brt.
of people than cars and two-wheelers.
                                               development of environmentally sus-           9. “Improving Urban Air Quality in
While a car or a scooter on an average                                                           South Asia by Reducing Emissions
carries 2 passengers; a bus on an av-          tainable transport systems.
                                                     In addition, use of alternative fu-         from Two-Stroke Engine Vehicles,
erage carries over 80 passengers per                                                             Masami Kojima, Carter Brandon”,
trip. The central lane is the preferred        els and effective public transport and
                                                                                                 Jitendra Shah, December 2000,
location for the bus because it avoids         management can ensure a substan-
                                                                                                 The International Bank for Recon-
coming into conflict with left turning traf-   tial improvement in environmental con-
                                                                                                 struction and Development, The
fic. The dedicated lane in the middle of       ditions, despite continuing increases
                                                                                                 World Bank.
the road ensures that the bus traffic          in vehicle fleets and their utilization.
                                                                                             10. “Introduction into Urban Air Quality
does not interfere with the rest of the                                                          in Asia: Status, Impact and its Man-
smaller vehicles on the road.                  References                                        agement, Cornie Huizenga”, May
      On the other hand, bus lanes to-         1. “Air Pollution Control in the Trans-           Ajero and Herbert Fabian, Clean Air
wards the left of the road will provide           portation Sector: Third Phase Re-              Initiative, June 2005, Brussels.
convenience to commuters in terms of              search Report of the Urban Envi-           11. “Need for A Metro”, Delhi Metro Rail
reaching the bus stops. DIMTS offi-               ronmental Management Project”,                 Corporation Ltd., http://www.delhi
cials say that they are checking out              Institute for Global Environmental             metrorail.com/corporates/needfor_
“buses in the left lane models too. In            Strategies (IGES), 2007.                       mrts.html.
many cities such as Bogota (Colum-             2. “Air Pollution from Motor Vehicles,        12. “New Directions: Air pollution and
bia) and Brisbane (Australia), each bus           Asif Faiz, Christopher S. Weaver,              road traffic in developing countries”,
stop of such central lanes busways has            Michael P. Walsh”, World Bank Dis-             Atmospheric Environment, Volume
access to an overhead bridge (or un-              cussion Paper No. 349.                         34, Issue 27, 2000, pp 4745-4746.
derpass) to facilitate movement of bus         3. “Annual Report” 2006-07, Central           13. “Vehicular Pollution”, http://www.
passengers to and fro each side of the            Pollution Control Board, 2007.                 pollutionissues.com/Ve-Z/Vehicu-
road.                                          4. “Bus Rapid Transit (BRT) System                lar-Pollution.html.



                                                                                           TECH MONITOR        Nov-Dec 2008      23