Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055 Page 1 of 8 Can a “Blue Sky” Return to Indian Megacities? Prashant Kumar 1,2,* , Suresh Jain 3 , B.R. Gurjar 4 , Prateek Sharma 3 , Mukesh Khare 5 , Lidia Morawska 6 , Rex Britter 7 1 Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences (FEPS), University of Surrey, Guildford GU2 7XH, United Kingdom 2 Environmental Flow (EnFlo) Research Centre, FEPS, University of Surrey, Guildford GU2 7XH, United Kingdom 3 Department of Natural Resources, TERI University, Delhi, 10, Institutional Area, Vasant Kunj, New Delhi 110070, India 4 Department of Civil Engineering, Indian Institute of Technology, Roorkee, Roorkee 247667, Uttrakhand, India 5 Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India 6 International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street, Brisbane Qld 4001, Australia 7 Senseable City Laboratory, Massachusetts Institute of Technology, Boston, MA 02139, USA *Correspondence to: Tel. +44 1483 682762; fax: +44 1483 682135; Email addresses: [email protected], [email protected]Abstract: Deterioration of air quality in Indian megacities (Delhi, Mumbai or Kolkata) is much more significant than that observed in the megacities of developed countries. Densely packed high-rise buildings restrict the self-cleaning capabilities of Indian megacities. Also, the ever growing number of on-road vehicles, resuspension of the dust, and anthropogenic activities exacerbate the levels of ambient air pollution, which is in turn breathed by urban dwellers. Pollution levels exceeding the standards on a regular basis often result in a notable increase in morbidity and mortality. This article discusses the challenges faced by Indian megacities in their quest for sustainable growth, without compromising the air quality and urban way of life. Main Text: India has the largest number of megacities (3 out of ~25) in the world. Together, Delhi, Mumbai and Kolkata house approximately one–fifth of the total worldwide megacities population (UN, 2010). The year 1991 saw the opening of the Indian economy and markets that resulted in rapid urbanisation. One outcome was the increase in use of private vehicles using limited road space, often leading to congestion and public health concern over the prolonged exposure to greater emissions from road vehicles (Nel, 2005; Patankar and Trivedi, 2011). The sky over Indian megacities is rarely blue nowadays. While the blue color itself is not a direct indication of the cities air quality level, the absence of it is a visible warning sign of a serious problem related to air pollution. Recent estimates suggest that exposure to vehicle-emitted nanoparticles (Kumar et al., 2011a) and other pollutants (suspended particulate matter, SPM; sulphur dioxide, SO 2 ; and nitrogen dioxide, NO 2 ; Gurjar et al., 2010) cause ~11250 and ~10500 excess deaths in Delhi every year, respectively. Reports by the Central Pollution Control Board (CPCB) suggest a high correlation between increased outpatient visits to hospitals and elevated pollution levels in Delhi (CPCB, 2008a, b). In fact, ~1/3 of Delhi adults have been shown to carry one or more respiratory symptoms due to poor air quality, which surges to ~2/3 in children (CPCB, 2008a, b). Findings of the “six cities”
Transcript
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 1 of 8
Can a “Blue Sky” Return to Indian Megacities?
Prashant Kumar1,2,*
, Suresh Jain3, B.R. Gurjar
4, Prateek Sharma
3, Mukesh Khare
5,
Lidia Morawska6, Rex Britter
7
1Department of Civil and Environmental Engineering, Faculty of Engineering and Physical
Sciences (FEPS), University of Surrey, Guildford GU2 7XH, United Kingdom
2Environmental Flow (EnFlo) Research Centre, FEPS, University of Surrey, Guildford GU2
7XH, United Kingdom
3Department of Natural Resources, TERI University, Delhi, 10, Institutional Area, Vasant
Kunj, New Delhi 110070, India
4Department of Civil Engineering, Indian Institute of Technology, Roorkee, Roorkee
247667, Uttrakhand, India
5Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New
Delhi 110016, India
6International Laboratory for Air Quality and Health, Queensland University of Technology,
2 George Street, Brisbane Qld 4001, Australia
7Senseable City Laboratory, Massachusetts Institute of Technology, Boston, MA 02139, USA
Abstract: Deterioration of air quality in Indian megacities (Delhi, Mumbai or Kolkata) is
much more significant than that observed in the megacities of developed countries. Densely
packed high-rise buildings restrict the self-cleaning capabilities of Indian megacities. Also,
the ever growing number of on-road vehicles, resuspension of the dust, and anthropogenic
activities exacerbate the levels of ambient air pollution, which is in turn breathed by urban
dwellers. Pollution levels exceeding the standards on a regular basis often result in a notable
increase in morbidity and mortality. This article discusses the challenges faced by Indian
megacities in their quest for sustainable growth, without compromising the air quality and
urban way of life.
Main Text: India has the largest number of megacities (3 out of ~25) in the world. Together,
Delhi, Mumbai and Kolkata house approximately one–fifth of the total worldwide megacities
population (UN, 2010). The year 1991 saw the opening of the Indian economy and markets
that resulted in rapid urbanisation. One outcome was the increase in use of private vehicles
using limited road space, often leading to congestion and public health concern over the
prolonged exposure to greater emissions from road vehicles (Nel, 2005; Patankar and Trivedi,
2011). The sky over Indian megacities is rarely blue nowadays. While the blue color itself is
not a direct indication of the cities air quality level, the absence of it is a visible warning sign
of a serious problem related to air pollution. Recent estimates suggest that exposure to
vehicle-emitted nanoparticles (Kumar et al., 2011a) and other pollutants (suspended
particulate matter, SPM; sulphur dioxide, SO2; and nitrogen dioxide, NO2; Gurjar et al.,
2010) cause ~11250 and ~10500 excess deaths in Delhi every year, respectively. Reports by
the Central Pollution Control Board (CPCB) suggest a high correlation between increased
outpatient visits to hospitals and elevated pollution levels in Delhi (CPCB, 2008a, b). In fact,
~1/3 of Delhi adults have been shown to carry one or more respiratory symptoms due to poor
air quality, which surges to ~2/3 in children (CPCB, 2008a, b). Findings of the “six cities”
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 2 of 8
study (NSR, 2010) indicate that, in 2007, 24-h average ambient concentrations of SPM, PM10,
PM2.5 and NO2 in residential areas of Delhi and Mumbai were much higher than the CPCB
standards (Table S1). The indoor environment does not safeguard against outdoor pollution,
because outdoor air penetrates easily indoors (Hoek et al., 2008) where Indian city dwellers
spend more than 80% of their time (Massey et al., 2012) as in most countries around the
world (Heinrich, 2011; Wallace and Ott, 2011). Even in the absence of additional indoor
source contributions, indoor concentrations of PM10 and PM2.5 can reach between 50 and
100% of their outdoor counterparts inside naturally ventilated buildings (Morawska and
Salthammer, 2003). Given this fact, “clean air” in the context of megacities, and whether it is
available to the residents of Indian megacities, needs to be explored. “Clean air” is referred to
here as air with pollutant levels that fall below the WHO (2006) standards (Table S2) or the
“low concentration” category of the CPCB (i.e. <50% of those set as national standards). This
leads to the question: what is needed to achieve “clean air” objectives in Indian megacities?
Fig. S1 presents an interesting overview of annual mean PM10 levels in Indian cities and the
megacities worldwide (WHO, 2011). At par with Karachi, Delhi shows ~10-fold pollutant
concentration levels over the WHO limits or the levels in New York which appears to be the
cleanest megacity. Clearly, taking PM10 as a metric, all three Indian megacities are among the
top polluted cities in developing countries and up to 10-times more polluted than the
megacities in developed world. Inter-comparison of PM10 levels in various Indian cities
suggests that even the cleanest cities contained ~2-times higher annual PM10 concentrations
(with the dirtiest being 13-times higher) over the WHO guidelines. About eight of these
burgeoning cities show equal or more concentrations than those in the three Indian
megacities. Although such growing Indian cities are not the focus of this article, their
inhabitants are paying identical or even larger health penalties compared to those residing in
megacities (Banerjee et al., 2012; Salvi, 2011).
The “six city” study (NSR, 2010), which included Delhi and Mumbai, suggested that road
vehicles are the principal source for most pollutants, except PM10 and SPM (largely produced
by resuspension from paved and unpaved road dust), therefore lowering their levels should be
the first priority. Mitigation actions such as better maintenance of existing roads using
innovative environmental friendly road construction materials (e.g. polymers with improved
bitumen quality) as well as paving of unpaved roads and footpaths could help controlling the
resuspension of PM10 and SPM. On the other hand, limiting the emissions from combustion
sources such as road vehicles, refuse burning and diesel generator sets could work well in
minimising the emissions of other pollutants. For instance, introduction of compressed
natural gas (CNG) in all public modes of road transport and light duty commercial vehicles in
Delhi during 2001-2006 resulted in reduction in PM concentrations, in addition to CO, NOx
and SO2 levels. Further reduction in ambient pollutant concentrations by targeting the
combustion-derived emissions is possible given the past success stories, such as the
downward trend of SO2 and lead emission levels following the policy decisions regarding the
lead and sulphur content in fuels (from 10,000 ppm in mid-1990s to 500 ppm within 4 years
and to 50 ppm in 2010). However, this is still about 5 times higher than the ultra-low-sulphur
diesel used in Europe (Jones et al., 2012). Despite the above efforts, the current levels of
some of the combustion-derived air pollutants such as PM2.5 are up to ~7.5 times above the
24-h average standards in Delhi (NSR, 2010; WHO, 2011). These will require great efforts to
reduce them, if “clean air” targets are to be achieved. The ineffectiveness of the policy
interventions to meet the air quality goals is attributed to increase in the number of private
vehicles in addition to other factors discussed above. A modal shift from private to public
mode is likely to improve the effectiveness of various interventions. Moreover, any solution
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 3 of 8
must firstly reduce emissions at the source. Court-mandated measures applied in public
transport of Mumbai and Delhi have resulted in improvements in air quality, although the
case in Kolkata is less encouraging, since older vehicles are yet to be phased out or changed
to CNG. Besides the timely implementation of progressive emission norms and improvement
in fuel quality, adoption of successfully applied emission reduction methods elsewhere, such
as the installation of over 100 million non-polluting e-bikes by Chinese cities during the past
decade (Shuguang et al., 2011), hydrogen fuel based clean vehicles (Kumar et al., 2009) or
the use of subsidised electric vehicles in the UK and Europe, can also be of value.
However, the question remains as to whether India's air pollution problem would disappear if
vehicle emissions were significantly reduced. The same “six city” study (NSR, 2010) showed
that emissions from power plants, industries, domestic biomass burning, building and
construction activities are also of concern. Both short and long distance trans-boundary
pollution from surrounding areas can also increase the ambient air concentrations in India's
megacities. For example, Delhi and Kolkata are surrounded by suburban areas where
unregulated anthropogenic sources of domestic biomass burning and local diesel generators
(for continuity of electricity supply) are common. As recently shown, “unorganised industry”
is the main contributor to airborne metals in Delhi (Pathak et al., 2012). This indicates the
magnitude of the problem and the need for an emissions reduction to clean the air over these
megacities.
Moreover, there is yet another mega pollution source that must be addressed: the cities
themselves! Through the buildings’ high energy consumption, the cities themselves are
indirect pollution sources. It has been estimated that urban areas account for over 70% of
energy related greenhouse gas (GHG) emissions worldwide (CPCB, 2008a, b; Hoornweg et
al., 2011). The actual amount of emissions varies significantly between cities and countries.
For instance, Delhi was responsible for 1.5 tCO2 e/capita of GHG emissions in the year 2000
(the year when the data was available), Sydney, Australia contributed much higher emissions
in 2006, at 20.3 tCO2 e/capita (Hoornweg et al., 2011). These emissions contribute to global
atmospheric pollution and, thus, to the background pollution in the cities. Megacities in
developed countries tend to consume much more energy than those in developing countries
(the difference between Delhi and Sydney is of the order of 20 times!), which indicates that
future emissions in the latter will increase in line with their economic progress. Therefore,
when addressing urban sustainability, the issue of urban and building design, as well as
human behaviour should be brought into the picture, as this is where huge gains can be made
in energy reduction and air pollution (Fig. 1). This is of particular importance for megacities
which will grow into super megacities in the next one or two decades, as is the compounding
problem of global climate change and the impact this will have on indoor and outdoor air
quality and energy consumption. For example, temperature increases will drive even more
energy consumption and higher air pollution emissions for air conditioning in already hot
climate of India.
So can Indian megacities have a sustainable future growth without compromising on air
quality and urban life? A positive answer is possible through the proper management of
pollution, reduction of vehicle emissions, and regulation of “unorganised” industries (Fig. 1).
This should be underpinned by scientifically evaluated air pollution dispersion modelling and
forecasting systems that are fit for local use and capable of predicting the sudden occurance
of “extreme” pollution levels due to unfavourable meteorology and poor dispersal capacity at
busy traffic-intersections, in order to allow time for mitigation plans to be drafted and
implemented (Gokhale and Khare, 2007). For instance, modelling studies for the long range
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 4 of 8
transport of pollutants could objectively apportion the contribution from background and
remote sources to the pollution load in city centres (Wagstrom and Pandis, 2011). This would
help to identify appropriate control points, which can be prioritised in order to reduce
pollution levels in the cities. Lessons can still be learned from the developed world to ensure
the future of India's megacities and to manage future megacities. One such concept applied in
developed world is establishing sustainability metrics for cities. These metrics have been
successfully developed for growing cities such as Boston, Seattle and Chicago, to monitor
environmental, social and economic impacts (Fitzgerald et al., 2012). Conceputal framework
for sustanability metrics is also available for growing cities in India but requires
comprehensive evaluation and a protocol for its effective implementation (JNNURM., 2005).
Emission control measures and policies have helped in reducing the level of air pollutants in
Indian megacities over the past decade. Consequently, the air is cleaner, but it is still not
close to the “clean air” goal. PM10 levels are still unacceptably high and continue to be above
air quality standards (Sharma et al., 2013). PM2.5, which has recently attracted the attention of
regulatory authorities in India, is a concern, after being introduced as a standard in 2009. So
far, measured data show up to 7.5 and 2.5 times higher levels in Delhi and Mumbai,
respectively, than those prescribed by the CPCB (NSR, 2010). NOx levels continue to exceed
the standards at most monitoring stations (NSR, 2010). Nanoparticles, potentially the most
harmful of all pollutants (Heal et al., 2012; Kumar et al., 2013) as they can penetrate straight
into the lungs and blood stream (Donaldson et al., 2005), are not currently in the regulatory
picture (Kumar et al., 2011b). Preliminary investigations on nanoparticle measurements in
Indian megacities indicate roadside concentrations 10's of times higher than in European
megacities (Kumar et al., 2011a; Kumar et al., 2012). Limited efforts are made thus far to
bring together issues of sustainable living and air pollution. Better foresight is needed if
Indian cities are to reduce and maintain air pollution levels within the standard limits,
including plans to develop regulatory guidelines for pollutants that are currently not in the list
(e.g. nanoparticles, indoor air pollutants). Meeting the “clean air” goals – and returning to a
“blue sky” – in existing megacities may appear to be a distant dream, but this could well be
achieved for new and growing cities, if a holistic approach combined with a futuristic vision
Fitzgerald, B.G., O’Doherty, T., Moles, R., O’Regan, B., 2012. A quantitative method for the
evaluation of policies to enhance urban sustainability. Ecological Indicators 18, 371-378.
Gokhale, S., Khare, M., 2007. A theoretical framework for the episodic-urban air quality management
plan (e-UAQMP). Atmospheric Environment 41, 7887-7894.
Gurjar, B.R., Jain, A., Sharma, A., Agarwal, A., Gupta, P., Nagpure, A.S., Lelieveld, J., 2010. Human
health risks in megacities due to air pollution. Atmospheric Environment 44, 4606-4613.
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 5 of 8
Heal, M.R., Kumar, P., Harrison, R.M., 2012. Particles, air quality, policy and health. Chemical
Society Reviews 41, 6606-6630.
Heinrich, J., 2011. Influence of indoor factors in dwellings on the development of childhood asthma.
International Journal of Hygiene and Environmental Health 214, 1-25.
Hoek, G., Kos, G., Harrison, R., de Hartog, J., Meliefste, K., ten Brink, H., Katsouyanni, K.,
Karakatsani, A., Lianou, M., Kotronarou, A., Kavouras, I., Pekkanen, J., Vallius, M., Kulmala,
M., Puustinen, A., Thomas, S., Meddings, C., Ayres, J., van Wijnen, J., Hameri, K., 2008.
Indoor-outdoor relationships of particle number and mass in four European cities. Atmospheric
Environment 42, 156-169.
Hoornweg, D., Sugar, L., Trejos Gomez, C.L., 2011. Cities and greenhouse gas emissions: Moving
forward. Environment and Urbanisation 23, 207-227.
JNNURM., 2005. Jawaharlal Nehru National Urban Renewal Mission: Governance and Reforms.
Centre for Good Governance, Administrative College Staff of India pp. 36.
Jones, A.M., Harrison, R.M., Barratt, B., Fuller, G., 2012. A large reduction in airborne particle
number concentrations at the time of the introduction of “sulphur free” diesel and the London
Wallace, L., Ott, W., 2011. Personal exposure to ultrafine particles. Journal of Exposure Science and
Environmental Epidemiology 21, 20-30.
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 6 of 8
WHO, 2006. Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide.
Global update 2005 summary of risk assessment. Report no. WHO/SDE/PHE/OEH/06.02,
WHO, 2011. Urban outdoor air pollution database. Department of Public Health and Environment,
World Health Organization, Geneva, Switzerland http://www.who.int/phe (accessed 06
November 2012).
Fig. 1. A multi-layer conceptual framework showing the interlinkages between the
drivers/soures for air pollution (central rings), environmental sustainability (three circles),
and overriding concerns for the future development of megacities (triangle). The overalpping
central rings refer to various important sources of air pollution. The black coloured “outer
circle” surrounding these central rings depicts the treatment of these emissions through the
science, governance and regulatory practices aimed to reduce the air pollution expsoure of
city dwellers. The outer circles indicate the “three pillars of sustanability” which are needed
to be considered whilst treating the emissions through governance. The overlapping traingle,
which is synonomous to sustainability pillars but with better directed challenges, indicates
overriding concerns for the future development of megacities that are needed to be tackled
whilst implementing the emission control strategies and other sustainability measures.
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 7 of 8
Supplementary Information (e-material)
0 50 100 150 200 250
LudhianaKanpur
LucknowIndore
AgraFaridabad
JabalpurDhanbad
AllahabadPatna
MeerutJaipur
VaranasiPune
NagpurBhopal
VijayawadaBangalore
RajkotHyderabad
VisakhapatnamSurat
NashikAhmedabad
VadodaraCoimbatore
ChennaiMadurai
KochiDelhi
KolkataMumbaiKarachi
CairoMexicali
DhakaLagos
BeijingTehran
ShanghaiGuangzhou
SeoulRio de Janeiro
IstanbulBangkok
Metro ManilaJakarta
Buenos AiresParis
LondonOsaka
Los AngelesTokyo
New York
Annual mean PM10 (µg m-3)
WHO PM10 annual mean (20 µg m–3)
Megacities worldwide
Other Indian cities
Indian megacities
CPCB PM10 annual mean (60 µg m–3)
Fig. S1. Annual mean PM10 concentrations in various cities and megacities within and
outside India; taken from WHO urban outdoor pollution database (WHO, 2011).
Cite this article as: Kumar, P., Jain, S., Gurjar, B.R., Sharma, P., Khare, M., Morawska, L., Britter, R., 2013. New Directions: Can a “Blue Sky” return to Indian megacities? Atmospheric Environment 71, 198-201. http://dx.doi.org/10.1016/j.atmosenv.2013.01.055
Page 8 of 8
Table S1: National Ambient Air Quality Standards in India.
Pollutant Time
weighted
average
Concentration in ambient air
(µg/m3)
Industrial,
Residential,
Rural and
Other area
Ecologically
Sensitive
Area
(notified by
Central
Govt.)
Methods of
Measurements
SO2: Sulphur Dioxide Annuala
24 hoursb
50
80
20
80
-Improved West and
Gaeke
-Ultraviolet
fluorescence
NO2: Nitrogen
Dioxide
Annuala
24 hoursb
40
80
30
80
-Modified Jacob &
Hochheiser (Na-
Arsenite)
-Chemiluminescence
PM10: Particulate
matter with
aerodynamic diameter
of 10 µm or less
Annuala
24 hoursb
60
100
60
100
-Gravimetric
-TOEM
-Beta attenuation
PM2.5: Particulate
matter with
aerodynamic diameter
of 2.5 µm or less
Annuala
24 hoursb
40
40
40
60
-Gravimetric
-TOEM
-Beta Attenuation
aAnnual arithmetic mean of minimum 104 measurements in a year at a particular site taken
twice a week 24 hourly at uniform intervals b24 hourly or 08 hourly or 01 hourly monitored values are applicable shall be compiled with
98% of the time in a year. 2% of the time they may exceed the limits but not on two
consecutive days of monitoring
Table S2: Ambient Air Quality Guidelines by the World Health Organisation (WHO, 2006).
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