Based on the Source Apportionment Studies carried out in six cities, the
following broad conclusions emerge, which provide guidance, with adequate
scientific evidence, to plan strategies for improving air quality in urban areas:
1. Levels of PM10 and PM2.5 in the ambient air are significantly high
irrespective of the type of locations. Even background locations indicate
presence of considerable levels of particulates, which could be occurring
naturally and/or due to transport of finer dust from other settlements
surrounding the cities. The concentrations of these pollutants are relatively
higher at kerbside/roadside locations. While vehicles contribute
significantly at all the locations, their contributions at kerbside locations
are comparatively higher.
2. Winter and post monsoon seasons had been found most critical when
standard exceedence rates are higher than in the summer months.
3. PM pollution problem is severe and NO2 is the emerging pollutant. These
two pollutants require immediate attention to control their emissions.
4. O3 concentrations in all cities did not exceed the proposed hourly
standard of 180 μg/m3 at any of the locations, where sampling was done.
However, in case of Mumbai and Pune, the peak hourly concentration
observed is very close to 180 μg/m3 (90 ppb). Although higher ozone
concentrations are expected around 1 – 3 pm, but it appears that good
dilution and high speed winds (in afternoon) bring the concentration
down. As such, O3 does not seem to be of much concern. Similarly, CO
levels may exceed marginally the hourly standard of 4000 μg/m3 in at a
few kerbside locations. In all cities, there are morning and evening peaks
in CO levels corresponding to vehicular movement.
5. With regard to air toxics, Benzene levels are higher in Bangalore, Pune
and Kanpur. The values of formaldehyde are also matter of concern in
Mumbai, Pune and Bangalore.
6. High Elemental Carbon (EC) to Organic Carbon (OC) ratio (EC/OC)
represents freshly contributed diesel/coal combustion particles biomass
and garbage burning. Many cities have shown this ratio to be high at
kerbside and industrial locations. EC and OC contribution to PM2.5 is even
more than what it is to PM10; and have high (25 – 75%) values in all the
cities. It signifies an important point that PM2.5 has much higher
component of toxic EC and OC that mostly come from combustion
sources like vehicles and others.
7. Higher fraction of PM2.5 in PM10, and higher values of EC and OC (which
have more severe health impacts) at kerbside locations indicate that
control of vehicular exhaust would be an important element of any
strategy or action plan for improving air quality and minimizing adverse
effects on the health of people.
8. Elemental and ion analysis show abundance of soil constituents (e.g. Si,
Fe, Ca, Na). This clearly suggests that there could be significant sources of
particulate pollution from soil, and road dust. The soil related fraction
drops down drastically (about 5% against 15 – 60% in PM10) in PM2.5. The
re-suspension of road dust due to vehicular movements on
paved/unpaved roads and construction activities, emerging as
prominent sources, would largely be contributing to coarser fraction of
PM10 and combustion sources including vehicles, DG sets, refuse burning,
etc. would emit particles in the finer size (< PM2.5). Hence, strategies for
reduction of PM10 and PM2.5 would involve different categories of sources.
9. There are significant quantities of SO42– and NO3–, (10-15% in most cities
and 20-30% in Kanpur) in PM10 indicating an important contribution of
secondary particles. These contributions are even high at the
background upwind direction in all cities. It signifies long-range transport
of particles in the city as well as formation of secondary particles in the
city. Any control strategy for reduction of particulate will have to
consider control of SO2, NO2 and NH3.
10. The presence of molecular markers like hopanes and steranes in much
higher quantities compared to background location indicates that effect
of vehicles is prevalent. Higher concentration of levoglucosan confirms
contribution from biomass burning.
11. Within the transport sector, the PM10 contribution in terms of emission load
is mainly from heavy duty diesel vehicles (40 – 59%) in almost all the cities.
With regard to NOx emissions, again heavy duty vehicles are major
contributors (43 – 75%).
12. Though, there are city-specific variations among the dominance of
sources, re-suspension of road dust and combustion sources including
vehicles, refuse burning & DG sets; emerge as prominent sources in all the
cities for PM.
13. Several epidemiological studies have linked PM10 and especially PM2.5
with significant health problems. PM2.5 is of specific concern because it
contains a high proportion of toxins, and aerodynamically it can
penetrate deeper into the lungs. Therefore, while planning control
strategies greater emphasis is to be given on reduction of PM2.5 and toxic
constitutes of particulates.
14. An effective control strategy would require combination of engineering
as well as non-engineering solutions. Prioritization of these solutions, in
addition to their effectiveness, should also be driven by the comparative
account of short and long term implementation dilemma. Low cost with
high effectiveness and low cost with shorter implementation period shall
be a better option, when compared with high effectiveness with high
costs or long implementation period.
15. Based on the findings of the study, some of the important steps required
for improving the air quality in urban areas are given below.
(i) Better maintenance of roads, paving of unpaved roads, footpaths or
low-elevation concreting of unpaved surfaces along major roads
with high traffic. Use of fly ash bricks could be considered as an
option for pavement that would also help in utilization of fly ash.
(ii) Agencies responsible for road construction & maintenance (MoRTH,
City Development Authority) should prepare guidelines for reducing
silt load on roads.
(iii) With regard to minimizing vehicular emissions, following actions are
required:
Implementation of progressive norms:
o Progressive tightening of emission regulations since 1991 to
BS-III regulations for 2& 3 wheelers and BS-IV regulations for all
other categories of vehicles (in line EURO-IV) implemented in
2010; have given an edge over the multifold growth of cities
and Mega cities of India and in turn the number of vehicles.
o The implementation roadmap for emission regulations for all
categories of vehicles in the short and medium run need to
be prepared and has to be updated on the continuous
basis.
o Progressive tightening of emission regulations may be
implemented. As a next stage universalization of BS IV norms
throughout the country and subsequently introduction of BS –
V regulations, taking into account environmental and
economic factors may be considered.o New vehicles to be introduced in future also have to be
compliant to the auto fuel norms that may be prescribed.
Road map for fuel quality improvement
o Since year 2000, differential norms are implemented in metros
and rest of the country due to non-availability of uniform
quality fuel across the country. Due to non-availability of
appropriate quality fuel, the vehicles of advance technology
registered in metros and major cities are deteriorating fast
defeating the purpose.
o BS-III regulations except for 2&3 wheelers are implemented in
12 cities of India since 2005. However, there will be vehicles
plying in these cities which are not registered in these cities
and such numbers are also high due to local tax structures.
Similarly, BS-III fuel is available only in the city and not even
20-30km away from city boundary. Considering the
circumferential growth of these cities, the number of city
vehicles traveling out of the city boundary is much higher
and tend to refuel the vehicles outside the city because of
the lesser cost of the fuel. Thus not using the required fuel,particularly low sulfur content fuel, deteriorates the emission
performance of these vehicles and in turn increases the inuse
vehicle emissions.
o Ensuring nationwide same quality of fuel will definitely
improve the conditions of in-use vehicle pollution noticeably
due to the fact that the after-treatment devices and other
newer technologies are very susceptible to the quality of fuel
used. Very short distance exposure to low grade fuel quality
may damage these devices permanently and thus making
newer generation of in-use vehicles not effective or even
worse than those of earlier generation vehicles due to the
failures of emission control devices. With this background, it is
desirable to have the policy of ‘One country One fuel quality
and One regulation’.
Restricting entry of polluting trucks and heavy duty goods
vehicles, and banning of old commercial vehicles in the cities.
As old vehicles emit more, a comprehensive vehicle scarp policy
needs to be evolved.
In place of existing PUC scheme, mandatory periodical
inspection and maintenance requirements may be considered.
Authorized service stations may issue certificates, after servicing
of the vehicles, with details of inspections/maintenance jobs
carried out.
(v) Guidelines to be prepared for better construction practices and strict compliance of the same is to be ensured.
(vi) Garbage/refuse burning should be strictly banned and efforts should be made to minimize biomass use for domestic purposes.
(vii) A time-bound action plan for reduction in use of biomass for cooking may be prepared.
(viii) Reduction in use of DG sets by ensuring adequate power supply, and have stricter norms for DG set emissions.
(ix) Use of cleaner fuels, stricter emission norms for industries located in and around the cities. As multiple agencies are involved,
following broad conclusions emerge, which provide guidance, with adequate
scientific evidence, to plan strategies for improving air quality in urban areas:
1. Levels of PM10 and PM2.5 in the ambient air are significantly high
irrespective of the type of locations. Even background locations indicate
presence of considerable levels of particulates, which could be occurring
naturally and/or due to transport of finer dust from other settlements
surrounding the cities. The concentrations of these pollutants are relatively
higher at kerbside/roadside locations. While vehicles contribute
significantly at all the locations, their contributions at kerbside locations
are comparatively higher.
2. Winter and post monsoon seasons had been found most critical when
standard exceedence rates are higher than in the summer months.
3. PM pollution problem is severe and NO2 is the emerging pollutant. These
two pollutants require immediate attention to control their emissions.
4. O3 concentrations in all cities did not exceed the proposed hourly
standard of 180 μg/m3 at any of the locations, where sampling was done.
However, in case of Mumbai and Pune, the peak hourly concentration
observed is very close to 180 μg/m3 (90 ppb). Although higher ozone
concentrations are expected around 1 – 3 pm, but it appears that good
dilution and high speed winds (in afternoon) bring the concentration
down. As such, O3 does not seem to be of much concern. Similarly, CO
levels may exceed marginally the hourly standard of 4000 μg/m3 in at a
few kerbside locations. In all cities, there are morning and evening peaks
in CO levels corresponding to vehicular movement.
5. With regard to air toxics, Benzene levels are higher in Bangalore, Pune
and Kanpur. The values of formaldehyde are also matter of concern in
Mumbai, Pune and Bangalore.
6. High Elemental Carbon (EC) to Organic Carbon (OC) ratio (EC/OC)
represents freshly contributed diesel/coal combustion particles biomass
and garbage burning. Many cities have shown this ratio to be high at
kerbside and industrial locations. EC and OC contribution to PM2.5 is even
more than what it is to PM10; and have high (25 – 75%) values in all the
cities. It signifies an important point that PM2.5 has much higher
component of toxic EC and OC that mostly come from combustion
sources like vehicles and others.
7. Higher fraction of PM2.5 in PM10, and higher values of EC and OC (which
have more severe health impacts) at kerbside locations indicate that
control of vehicular exhaust would be an important element of any
strategy or action plan for improving air quality and minimizing adverse
effects on the health of people.
8. Elemental and ion analysis show abundance of soil constituents (e.g. Si,
Fe, Ca, Na). This clearly suggests that there could be significant sources of
particulate pollution from soil, and road dust. The soil related fraction
drops down drastically (about 5% against 15 – 60% in PM10) in PM2.5. The
re-suspension of road dust due to vehicular movements on
paved/unpaved roads and construction activities, emerging as
prominent sources, would largely be contributing to coarser fraction of
PM10 and combustion sources including vehicles, DG sets, refuse burning,
etc. would emit particles in the finer size (< PM2.5). Hence, strategies for
reduction of PM10 and PM2.5 would involve different categories of sources.
9. There are significant quantities of SO42– and NO3–, (10-15% in most cities
and 20-30% in Kanpur) in PM10 indicating an important contribution of
secondary particles. These contributions are even high at the
background upwind direction in all cities. It signifies long-range transport
of particles in the city as well as formation of secondary particles in the
city. Any control strategy for reduction of particulate will have to
consider control of SO2, NO2 and NH3.
10. The presence of molecular markers like hopanes and steranes in much
higher quantities compared to background location indicates that effect
of vehicles is prevalent. Higher concentration of levoglucosan confirms
contribution from biomass burning.
11. Within the transport sector, the PM10 contribution in terms of emission load
is mainly from heavy duty diesel vehicles (40 – 59%) in almost all the cities.
With regard to NOx emissions, again heavy duty vehicles are major
contributors (43 – 75%).
12. Though, there are city-specific variations among the dominance of
sources, re-suspension of road dust and combustion sources including
vehicles, refuse burning & DG sets; emerge as prominent sources in all the
cities for PM.
13. Several epidemiological studies have linked PM10 and especially PM2.5
with significant health problems. PM2.5 is of specific concern because it
contains a high proportion of toxins, and aerodynamically it can
penetrate deeper into the lungs. Therefore, while planning control
strategies greater emphasis is to be given on reduction of PM2.5 and toxic
constitutes of particulates.
14. An effective control strategy would require combination of engineering
as well as non-engineering solutions. Prioritization of these solutions, in
addition to their effectiveness, should also be driven by the comparative
account of short and long term implementation dilemma. Low cost with
high effectiveness and low cost with shorter implementation period shall
be a better option, when compared with high effectiveness with high
costs or long implementation period.
15. Based on the findings of the study, some of the important steps required
for improving the air quality in urban areas are given below.
(i) Better maintenance of roads, paving of unpaved roads, footpaths or
low-elevation concreting of unpaved surfaces along major roads
with high traffic. Use of fly ash bricks could be considered as an
option for pavement that would also help in utilization of fly ash.
(ii) Agencies responsible for road construction & maintenance (MoRTH,
City Development Authority) should prepare guidelines for reducing
silt load on roads.
(iii) With regard to minimizing vehicular emissions, following actions are
required:
Implementation of progressive norms:
o Progressive tightening of emission regulations since 1991 to
BS-III regulations for 2& 3 wheelers and BS-IV regulations for all
other categories of vehicles (in line EURO-IV) implemented in
2010; have given an edge over the multifold growth of cities
and Mega cities of India and in turn the number of vehicles.
o The implementation roadmap for emission regulations for all
categories of vehicles in the short and medium run need to
be prepared and has to be updated on the continuous
basis.
o Progressive tightening of emission regulations may be
implemented. As a next stage universalization of BS IV norms
throughout the country and subsequently introduction of BS –
V regulations, taking into account environmental and
economic factors may be considered.o New vehicles to be introduced in future also have to be
compliant to the auto fuel norms that may be prescribed.
Road map for fuel quality improvement
o Since year 2000, differential norms are implemented in metros
and rest of the country due to non-availability of uniform
quality fuel across the country. Due to non-availability of
appropriate quality fuel, the vehicles of advance technology
registered in metros and major cities are deteriorating fast
defeating the purpose.
o BS-III regulations except for 2&3 wheelers are implemented in
12 cities of India since 2005. However, there will be vehicles
plying in these cities which are not registered in these cities
and such numbers are also high due to local tax structures.
Similarly, BS-III fuel is available only in the city and not even
20-30km away from city boundary. Considering the
circumferential growth of these cities, the number of city
vehicles traveling out of the city boundary is much higher
and tend to refuel the vehicles outside the city because of
the lesser cost of the fuel. Thus not using the required fuel,particularly low sulfur content fuel, deteriorates the emission
performance of these vehicles and in turn increases the inuse
vehicle emissions.
o Ensuring nationwide same quality of fuel will definitely
improve the conditions of in-use vehicle pollution noticeably
due to the fact that the after-treatment devices and other
newer technologies are very susceptible to the quality of fuel
used. Very short distance exposure to low grade fuel quality
may damage these devices permanently and thus making
newer generation of in-use vehicles not effective or even
worse than those of earlier generation vehicles due to the
failures of emission control devices. With this background, it is
desirable to have the policy of ‘One country One fuel quality
and One regulation’.
Restricting entry of polluting trucks and heavy duty goods
vehicles, and banning of old commercial vehicles in the cities.
As old vehicles emit more, a comprehensive vehicle scarp policy
needs to be evolved.
In place of existing PUC scheme, mandatory periodical
inspection and maintenance requirements may be considered.
Authorized service stations may issue certificates, after servicing
of the vehicles, with details of inspections/maintenance jobs
carried out.
Management options like synchronizing traffic signals, staggering business hours, restricting vehicular movements in certain areas with high pollution levels (particularly during peak hours and/or critical season), fiscal incentives/disincentives (e.g. increased parking fee, proper fuel pricing policy), banning odd/even vehicles on major roads, etc. may be considered.
Development of mass rapid transportation system. This will
reduce traffic congestion, smaller personalized VKT, and reduce soil and road dust re-suspension.
Financial incentives on non-polluting vehicles like electric- hybrid will also increase the penetration of these vehicles in public as well as in personal vehicles category.
(iv) Certain highly polluting areas (hotspots) can be identified as low emission zone and very specific norms are applied including restrictions on certain activities. Development of mass rapid transportation system. This will
reduce traffic congestion, smaller personalized VKT, and reduce soil and road dust re-suspension.
Financial incentives on non-polluting vehicles like electric- hybrid will also increase the penetration of these vehicles in public as well as in personal vehicles category.
(v) Guidelines to be prepared for better construction practices and strict compliance of the same is to be ensured.
(vi) Garbage/refuse burning should be strictly banned and efforts should be made to minimize biomass use for domestic purposes.
(vii) A time-bound action plan for reduction in use of biomass for cooking may be prepared.
(viii) Reduction in use of DG sets by ensuring adequate power supply, and have stricter norms for DG set emissions.
(ix) Use of cleaner fuels, stricter emission norms for industries located in and around the cities. As multiple agencies are involved,
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