Air Pollution in Mega Cities: A Case Study of Istanbul

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Air Pollution in Mega Cities:
A Case Study of Istanbul
Selahattin Incecik and Ulaş Im
1Istanbul Technical University, Department of Meteorology, Maslak, Istanbul
2University of Crete Department of Chemistry, Environmental Chemical
Processes Laboratory (ECPL) Voutes, Heraklion, Crete
1Turkey
2Greece
1. Introduction
A megacity is defined by the United Nations as a metropolitan area with a total population
of more than 10 million people. This chapter provides a brief introduction to the air
pollution in megacities worldwide. This is an extensive topic and brings together recent
comprehensive reviews from particular megacities. We have here highlighted the air quality
in megacities that are of particular relevance to health effects.
The main objective of this chapter is to enhance our understanding of the polluted
atmosphere in megacities, with respect to the emission characteristics, climate, population
and specific meteorological conditions that are leading to episodes. Therefore, the chapter
will provide state-of-the-art reviews of air pollution sources and air quality in some selected
megacities, particularly Beijing, Cairo, Delhi and Istanbul. Furthermore, a detailed analysis
of emission sources, air quality, mesoscale atmospheric systems and local meteorology
leading to air pollution episodes in Istanbul will be extensively presented.
The world population is expected to rise by 2.3 billion, passing from 6.8 billion to 9.1 billion
in between 2009 and 2050 (UN Report, 2010). Additionally, population living in urban areas
is projected to gain 2.9 billion from 3.4 to 6.3 billion in this period. However, during the
industrial revolution years, only about 10% of the total population lived in the cities. As an
example, in 1820, which is the beginning times of the United States (US) transformation
from rural to urban, the great majority of the population lived in rural areas of US (about
96%) (Kim, 2007). Today, according to UN Report the world population in urban areas has
reached to 50.5%. In other words, half of the world's population are concentrated in the
cities. However, distribution of urban population in the world is not evenly. A significant
diversity in the urbanization levels can be seen in different regions of the world. About 75%
of the inhabitants of the more developed regions lived in urban areas in 2010, whereas this
ratio was 45% in the less developed regions. It is expected that urbanization will continue to
rise in both more developed and less developed regions by 2050 with about 86% and 69%,
respectively. These developments have created new physical, social and economic processes
in the cities. For example, uncontrolled urban sprawl has leaded the rising of environmental

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78
problems due to high traffic volume, irregular industry, and low quality housing, etc.
Massive urbanization in the cities due to the better job opportunities and challenges in the
urban areas began first in Europe and then in other regions of the world, particularly in Asia.
At this point, urbanization levels have led to a new classification and a concept- megacity-
which is usually defined as a metropolitan area with a total population in excess of 10 million
inhabitants. Megacities are highly diverse in the world, spanning from Paris (France), Los
Angeles, New York City (USA) in developed countries to Delhi (India), Dhaka (Bengladesh)
and Lagos (Nigeria) in developing countries. In today’s developing countries, megacities
exhibit the highest levels of pollution and therefore, in the studies of the anthropogenic impact
on atmospheric composition, have become of primary importance, particularly those having
high traffic volumes, industrial activities and domestic heating emissions.
The United Nations Environment Programme Urban Environment (UNEP-UE) unit
expressed that more than 1 billion people are exposed to outdoor air pollution annually and
the urban air pollution is linked to up to 1 million premature deaths and 1 million pre-native
deaths each year. Additionally, UNEP presented the cost of urban air pollution with
approximately 2% of GDP in developed countries and 5% in developing countries,
respectively. In addition, the UNEP/Global Environmental Monitoring System (GEMS)
reported that rapid industrialization, burgeoning cities, and greater dependency on fossil
fuels have caused increasing production of harmful pollutants, creating significant health
problems in most urban cities. The serious air quality problems, specifically inverse health
effects, have been experienced in megacities of both developing and developed countries.
due to the exposure to high concentrations of particular matter (PM), nitrogen oxides (NOx),
ozone (O3), carbon monoxide (CO), hydrocarbons (HC) and sulfur dioxide (SO2) depending
on country’s technology level. Especially, exposure to eleveted levels of particular matter
and surface ozone causes loss of life-expectancy, acute and chronic respiratory and
cardiovascular effects. Furthermore, damage to the ecosystem biodiversity by excess
nitrogen nutrient is an important consequence of pollution.
In the beginning of the 2011, The European Commusion released a paper about the current
policy efforts and the expected results to maintain a hard line against countries that are yet
to comply with EU air quality legistlation limiting fine particulate matter (PM2.5)
concentrations. WHO (2009) concluded that megacities have faced particularly health
impact by transportation, governance, water and sanitation, safety, food security, water and
sanitation, emergency preparedness, and environmental issues. Furthermore, Baklanov
(2011) recently shared results of the EU MEGAPOLI project (Megacities: Emissions, Impact
on Air Quality and Climate, and Improved Tools for Mitigation and Assessment), which
focuses on the multiple spatial and temporal scales from street to global levels and vice
versa. The project addresses megacities with air quality and climate having complex effects
on each other. Another EU-funded project CityZen (Megacities: Zoom for the Environment)
also focused on impact of megacities on their environment and climate and vice versa from
local to global aspects using long-term ground and satellite observations as well as regional
and global modeling.
2. Megacities and air quality
As of 2011, there are 26 megacities in the world such as Tokyo, Guangzhou, Seoul, Delhi,
Mumbai, Mexico City, New York City, Sao Paulo, Istanbul and other sixteen , eight of

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which exceeds 20 million. Fig. 1 presents the population in megacities world-wide with
their continents. The four of the megacities are located at the South Hemisphere. Fifteen
megacities are located at the tropical and humids-subtropical regions. This characteristic
is important due to the growing evidence of the climate–health relationships posing
increasing health risks under future projections of climate change and that the warming
trend over recent decades has already contributed to increased morbidity and mortality in
many regions of the world (Patz, et al., 2005). A total of 14 megacities, corresponding to
more than of 50% of the total megacities, are located at the Asia continent, particularly in
south and east parts. In this very dynamic region of the world, there are significant
increases in industrialization and urbanization enhanced the urban population growth
and economic development. This also leads to drastic increases in energy consumption
and pollutant emissions in these regions. As an example, China is a rapid developing
country with an urban population rate that increased from 19.6% to 46% within the last
three decades.
Fig. 1. Populations of the megacities with respect to their continents.
According to “China’s blue paper”, urban population ratio will reach 65% by 2030 in China.
In recent years, a remarkable increase in the number of studies for air quality in China has
been conducted (Kai et al., 2007; Chan and Yao, 2008; Wu et al., 2008; Fang et al., 2009; Wang
et al, 2010;Zhu et al., 2011; Jahn et al., 2011). As an example, Chan and Yao (2008) extensively
discussed the urbanization and air quality characteristics in Beijing, Shanghai and cities in
Pearl River Delta (PRD) which is the mainland of China’s leading commercial and
manufacturing region covering Guangzhou, Shenzhen and Hong Kong. They noticed that in
spite of the much attention to reduce emissions through effective control measures,
particulate pollution is still severe in megacities of China. Among them, Guangzhou, which
is the fourth largest city in China, is the main manufacturing hub of the PRD. In this city, the
major industries are located in this industrial zone. In an earlier study by Kai et al. (2007) Air
Pollution Index (API) values of Guangzhou were compared with the values of Shanghai and
Beijing. The API for Guangzhou is higher than those of Beijing and Shanghai indicating that
TSP was the prominent pollutant accounting for 62% of the major share in Guangzhou

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(Zhou et al., 2007). In order to improve the air quality in Guangzhou, several new strategic
efforts have been planned and established in industry and transportation sectors. Examples
of the new control measures in transportation are; the metro line, which was opened in 1997,
bus rapid transit system, hybrid buses, and design of low-emission zones in busy traffic areas.
In a very recent study, Zhu et al. (2011) investigated the transport pathways and potential
sources of PM10 in Beijing.
On the contrary to the classical air pollution events in megacities that are above mentioned,
Los Angeles, USA (34o03’N; 118o15’W) which is in a large basin surrounded by the Pacific
Ocean to the west and several mountain peaks to the east and south, and having a
population of over 18 million, remains the most ozone-polluted region in the country. The
Los Angeles region, which has a subtropical Mediterranean climate, enjoys plenty of
sunshine throughout the year. The frequent sunny days and low rainfall contribute to ozone
formation and accumulation as well as high levels of fine particles and dust in Los Angeles.
The city area has the highest levels of ozone nationwide, violating federal health standards
with an average of 137 days a year. The population growth, dependence on private motor
vehicles, and adverse natural meteorological conditions can lead the episodic air quality
levels in this area.
2.1 The general characteristics of air pollution and emission sources in megacities
Air pollution in urban areas comes from a wide variety of sources. The sources responsable
for high emission loads are grouped into several sectors such as transport, domestic
commercial and industrial activities for anthropogenic sources and NMVOCs from biogenic
sources. Transport sector includes mainly motor vehicles, trains, aircraft, ship and boats
while industry and domestic activities include fuel combustion including wood, coal, and
gas for heating and production. Besides, biogenic (natural) emissions include NOx and VOC
emissions from vegetation and soils (Guenther et al., 2006). Today, urban air quality is a
major concern throughout the world. Molina (2002) indicated that the quality of the air we
breathe is fundamental to the quality of life for the growing millions of people living in the
world's burgeoning megacities and deteriorating urban air quality threatens the public
health. Furthermore, airborne emissions from major urban and industrial areas influence
both air quality and climate change. This challenge is particularly acute in the developing
world where the rapid growth of megacities is producing atmospheric pollution of
unprecedented severity and extent. Mage et al. (1996) reviewed the difficulties in finding
solutions to the air pollution in the megacities. Baldasano et al. (2003) examined the air
quality for the principal cities in developed and developing countries. According to the
study, the current state of air quality worldwide indicates that SO2 maintains a downward
tendency throughout the world, with the exception of some Central American and Asian
cities, whereas NO2 maintains levels very close to the WHO guideline value in many cities.
However, in certain cities such as Kiev, Beijing and Guangzhou, the figures are
approximately three times higher than the WHO guideline value. In the Asian databases
consulted, only Japan showed really low figures. Surface ozone levels presents average
values that exceed the selected guideline values in all of the analysis by regions, income
level and number of inhabitants, demonstrating that this is a global problem with
consequences for rich and poor countries, large and medium cities and all the regions.

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Gurjar et al. (2008) examined the emissions and air quality pertaining to the megacities. He
and his colleagues ranked megacities in terms of their trace gas and particle emissions and
ambient air quality, based on the newly proposed multi-pollutant index (MPI) which
considers the combined level of the three criterion pollutants (TSP, SO2 and NO2) in view of
the World Health Organization (WHO) guidelines for air quality. Simulations of the export of
air pollution from megacities to downwind locations via long-range transport (LRT) have
shown different transport patterns depending on the megacity location: in the tropics export is
occurring mostly via the free troposphere, whereas at mid and high latitudes it occurs within
the lowest troposphere (Lawrence et al., 2007). Butler & Lawrence (2009) simulated small
impacts of megacities on the oxidizing capacity of the atmosphere and larger on reactive
nitrogen species on global scale. They also pointed out the need of parameterization of the sub-
grid effects of megacities. Butler et al. (2008) analyzed different emission inventories and found
substantial differences in emission’s geographical distribution within countries even if the
country total emissions are the same. They also reported large differences in the contribution
of various sectors to the total emissions from each city.
Table 1 presents the megacities with their location, climate type, major emissions and
critical air quality parameters. As seen in Table 1, there is a significant geographical
variation in domestic heating emissions. Specifically, particulate matter is a major
problem in almost all of Asian and Latin cities. In all of the megacities, emissions from the
motor vehicles are a major contributor of harmful pollutants such as nitrogen oxides and
particulate matter. The most important source for the classical pollutants such as
particular matter, sulfur dioxide, nitrogen oxides, carbon monoxide, and volatile organic
compounds are combustion of fossil fuels.
3. Megacity of Beijing
Beijing (39°54′N; 116°23′E), the capital of China, has completed its third decade of
economic development known as the Economic Reform and Open Policy starting in 1978,
and is a rapidly developing megacity with a 16 million population (Fang et al., 2009). As
it’s the capital city, Beijing continues to experience substantial growth in population,
economic activity, business, travel and tourism. The city is situated at the northern tip of
the roughly triangular North China Plain, which opens to the south and east of the city.
Mountains to the north, northwest and west shield the city and northern China's
agricultural areas from the desert steppes. Beijing has been experiencing severe
anthropogenic air pollution problems since 1980s due to the significant energy
consumption depending on developments of the city. Furthermore, natural sources have a
significant impact on the city environment such as dust transport from the northern parts
of the city. This leads to polluted smog covering the city as a thick blanket under specific
meteorological conditions.
3.1 Climate
Beijing is in a warm temperate zone and has a typical monsoon–influenced humid
continental climate with four distinct seasons. It is usually characterized by hot and humid
summers and dry winters.

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Megacity Lat ; Lon Popul.
(million)
Area
(km2)Climate Type Major Emission
Source(s)
Critical Air
Quality
Parameters
Beijing
(CN) 39°54′N; 116°23′E 16.0 16,800
Monsoon-
influenced
humid
continental
Domestic
heating,
traffic,industry,
dust,biomass
burning
PM10,
PM2.5, NO2,
O3
Buenos
Aires
(ARG)
34°36′S; 58°22′W 15.0 4,758
Humid
subtropical
Motor vehicles,
industry CO, NOx
Cairo
(EGY) 30°3′N; 31°13′E 17.2 86,370 Hot and dry
desert
Industry, motor
vehicles,dust
transport
PM10,
PM2.5
Delhi
(IND) 28°36′N; 77°13′E 23.0 1,483
Humid
subtropical
Motor vehicles,
industry
PM10,
PM2.5, NO2
Dhaka
(BNG) 23°42′N; 90°22′E 14.6 360
Hot, wet and
humid tropical
Industry,road
dust, open
burning
PM10,
PM2.5, SO2
Guangzh
ou (CN) 23°08′N; 113°16′E 12.7 7,434
Humid
subtropical
Industry, motor
vehicles, power
generation
PM10, NO2
Istanbul
(TUR) 41°01′N; 28°58′E 13.2 5343 Mediterranean
Motor
vehicles,
industry
PM10, CO,
NOx
Jakarta
(IN) 6°12′S; 106°48′E 18.0 740
Hot and humid
tropical wet and
dry
Motor vehicles,
Industry
PM10, NO2,
O3,CO
Karachi
(PK) 24°51′N; 67°0′E 17.0 3,527 Arid
Industry,
Motor
vehicles
PM10 (TSP),
CO, NO2
Kolkata
(IND) 22°34′N; 88°22′E 15.6 1,480
Tropical wet
and dry
Domestic,
Motor vehicles,
Waste
PM10,NO2
Lagos
(NGR) 6o 25’N;3o 23’E 12.0 999 Tropical
savanna
Industr
y
, Motor
vehicles,
SO2, PM10,
NO2
London
(UK) 51°30′N; 0°7′W 12,6 1572 temperate Mostly traffic PM10, NO2
Los
Angeles
(USA)
34°3′N;118°15′W 17.7 1302
Subtropical-
Mediterranean
Motor vehicles,
petroleum
rafinery, power
generation
O3, NOx
Manila
(PHP) 14°35′N;120°58′E 20.8 638
Tropical
savanna/
tropical
monsoon climate
Power
generation,
industry motor
vehicles
PM10, SO2

Air Pollution in Mega Cities: A Case Study of Istanbul
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Megacity Lat ; Lon Popul.
(million)
Area
(km2)Climate Type Major Emission
Source(s)
Critical Air
Quality
Parameters
Mexico
City
(MEX)
19°26′N; 99°08′W 21,1 1,485
Subtropical hi
g
h
land Motor vehicles
PM10,
O3,BC
(soot), NO2
Moscow
(RUS) 55°45′N 37°37′E 16.0 1,081 Humid
continental
Motor vehicles,
Industr
y
, Power
generation
SO2, PM10,
NO2, CO
Mumbai
(IND) 18°58′N; 72°49′E 23.0 603
Tropical wet
and dry
Industr
y
, Motor
vehicles, Power
plants,
Domestic, land
fill open
burning, road
dust
PM10, PAH,
hazardeous
chemicals
New
York City
(USA)
40°43′N;74°00′W 19.0 1,214
Humid
subtropical Motor vehicles PM2.5, O3
Osaka
(JPN) 34°41′N; 135°30′E 16.6 222
Humid
subtropical Motor vehicles
PM10,
PM2.5, NO2,
O3
Paris (F) 48° 51′ N;02° 21′ E 11.8 14,518
Western
European
oceanic climate
Motor vehicles
PM10,
PM2.5, O3,
NO2
Rio de
Janeiro
(BR)
22°54′S; 43°11′W 14.4 4,557
Tropical
savanna climate
/ tropical
monsoon
Motor vehicles PM10, NO2
Sao Paulo
(BR) 23°33′S;46°38′W 22.0 7,944
Monsoon-
influenced
humid
subtropical
climate
Industr
y
, Motor
vehicles
PM10,
BC,O3
Seoul
(KR) 37°34′N;126°58′E 25.0 605
Humid
subtropical /
humid
continental
climate
Motor vehicles PM10, NO2,
O3
Shanghai
(CN) 31°12′N; 121°30′E 24.7 6,340
Humid
subtropical
Industr
y
, Motor
vehicles, Dust
transport
PM10, NO2
Tehran
(IRN) 35°41′N ;51°25′E 13.4 1,274
Semiarid
continental
Industr
y
, Motor
vehicles
CO, NO2,
PM10
Table 1. List of megacities and their characteristics.

Air Pollution – Monitoring, Modelling and Health
84
3.2 Air pollution sources
The major anthropogenic emission sources in Beijing are domestic heating, traffic and
industry. Coal dominated energy structure is also one of the major causes of air pollution in
Beijing (Hao, et al., 2007). As an example to the total emissions from energy production
sector of 16.0 GWh/y, Hao et al. (2007) calculated a 102,497 t/y of SO2, 60,567 t/y of NOx
and 11,633 t/y of PM10. Domestic heating in Beijing usually starts in mid-November and
ends in the following March and it is the major source for SO2 in the winter season (Chan
and Yao, 2008; Hao et al., 2005). Furthermore, industrial emissions emitted from Shijingshan
region, located west of Beijing, are significant sources of particulate matter in Beijing. Beijing
experiences a serious urban sprawl which has been claimed to be a major factor leading to
the need for long-distance travel, congestion in the city centre and private vehicle usage
problem (Zhao, et al., 2010; Deng & Huang, 2004). The number of cars in Beijing has grown
rapidly and reached to 4.76 million vehicles in 2011, up from 1.5 million in 2000 and 2.6
million in 2005, according to official statistics provided by the municipal transportation
authorities. Particulate matter emitted from motor vehicles and re-suspension of road dust
are also likely contributors to PM10 pollution in the city (Song et al., 2006). Last but not least,
natural dust originating from the erosion of deserts in northern and northwestern China
results in seasonal dust storms that plague the city.
3.3 Air quality in Beijing
Beijing is party to the Standard Ambient Air Quality Standards (GB 3095-1996), which sets
limits for SO2, CO, PM10 and nitrogen dioxide (NO2). The Chinese air quality standards set
separate limits for different types of areas such as Class I, II and III based on physical
characteristics of the region such as natural conservation areas and special industrial areas.
Beijing is designated as a Class II area, which applies to residential, mixed commercial/
residential, cultural, industrial, and rural areas.
TSP and SO2 have been the major pollutants in China for a long time due to the fossil fuel
burning from power plants, industry and domestic heating. However, in recent years, the
Chinese Government have planned to reveal a major environmental plan to help managing
air pollution and is expected to include efforts to reduce pollution through new regulations
and strategies including taxes and investments in this field. As an example, energy-related
measures include fuel substitution and flue gas desulfurization facilities, which were built at
the coal fired power plants, control measures such as energy efficiency and fuel use and
dust control improvements (Hao et al. 2007). Initiatives have also been implemented in
Beijing. The use of natural gas has been increased four-fold from 2000 as a result of efforts
made to replace coal fired boilers and family stoves to use natural gas, and coal heating with
electrical heating. As a result of these initiatives, from 1990 to 1999, the annual average TSP
concentration in 100 major cities decreased by 30% to 256 μg/m3 and it remained almost
constant from 1999 to 2003 (Sinton et al., 2004), despite an overall decrease of 30% in total
energy consumption from 1997 to 2002. Fang et al. (2009) examined the air quality
management in China and the changing air quality levels with their reasons. The results of
the new strategies in Beijing are seen in Fig.2. In 1998, Beijing started its phased intensive
control program to fight air pollution. PM10 concentrations increased by around 10% from
2003 to 2006 because of the increase in coal-fired boiler emissions, construction activities and
dust storms (United Nations Environment Program, 2007). The annual PM10 concentrations

Air Pollution in Mega Cities: A Case Study of Istanbul
85
in Beijing decreased from 162μg/m3 in 2006 to 141μg/m3 in 2007 despite an increase in
energy consumption. The recent measurements of PM10 indicates lower levels such as
123μg/m3 in 2008; 120μg/m3 in 2009, respectively. One of the reasons of the high level of
PM10 is residential coal-combustion in Beijing. SO2 emissions from residential coal-
combustion in Beijing were increased from 68,800 tons in 2003 to 85,100 tons in 2005. The
expansion of the urban areas and the increase in SO2 emissions led to increased particulate
sulfate concentrations, which resulted in higher PM10 levels. However, SO2 levels in the city
are decreasing (Fang et al., 2009). Furthermore, Beijing experiences high PM10 pollution
during spring dust storms. Zhu et al. (2011) showed that the typical wind speed of such dust
storms is approximately 7 m/s or more, and the sand and dust sources are located about
1000-2000 km northwest of Beijing. According to Zhu et al. (2011), dust storms can reach to
Beijing within 3 days.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0
20
40
60
80
100
120
140
160
180
2000 2002 2004 2006
CO (mgm
-3
)
PM10, SO2, NO2 (gm
-3
)
PM10 SO2 NO2 CO
Fig. 2. Variations of annual-mean PM10, SO2, NO2 (µgm-3) and CO (mgm-3) levels in Beijing
(2000-2008) *Air quality standard for PM10 is 100 µg/m3 and WHO guideliness is 20µg/m3.
Recently, heavy industries have been gradually replaced by less polluting industries in
Beijing. Besides, several possible activities are planned on major polluting industries such as
the closure of cookery units at coke and chemical plants as well as closure of cement, lime
and brick plants. The, transport sector is also a major contributor to Beijing’s air quality. In
this sector, stringent vehicle emission standards have been established. The Beijing
municipal government will also implement traffic control measures such as the
improvement of fuel quality to meet the new emission standards and to ease the city's traffic
congestion.
4. Megacity of Cairo
Greater Cairo (30o3’N; 31o13’E), which is the capital of Egypt, is the largest city in Africa and
located in northern Egypt, to the south of the delta in the Nile basin. The Greater Cairo

Air Pollution – Monitoring, Modelling and Health
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consists of Cario, Giza and Kalubia, and has a population of about 17 million inhabitants.
The city which about one-third of Egypt’s population and 60% of its industry and is one of
the world’s most densely populated cities. Gurjar, (2009) and Decker et al., (2000) reported
that Cairo’s population is confined in 214 km2 area making it the most densely populated
megacity. The urbanization and industrialzation have increased very rapidly in Greater
Cairo, particularly in the second half of the last century.
4.1 Climate
The climate in Cairo and along the Nile River Valley is characterized by a hot, dry desert
climate. Wind storms can be frequent, bringing Saharan dust into the city during the spring.
Abu-Allaban et al. (2002; 2007 and 2009) reported that wind speeds in wintertime is weaker
than during summer, implying a lower ventilation of the area during winter that could
favor pollutant accumulation in the vicinity of the sources. Additionally, Safar and Lebib
(2010) indicated that the arid climate in the city causes a persistent high background PM
level in the Cairo area.
4.2 Air pollutant emissions
The air pollution in Cairo is a matter of serious concern. The major emissions in the city
come from industry and motor vehicles which cause high ambient concentrations of PM,
SO2, NOx and CO. There are over 4.5 million cars on the streets of Cairo according to recent
records. The relative contribution to particulate pollution from different economic activities
is shown in Table 2. As seen in the table, the major contribution to the particulate load is
urban solid waste burning by 30%. Transport and industry follows the solid waste by 26%
and 23%, respectively. Kanakidou et al. (2011) summarized a comprehensive overview of
the actual knowledge on the atmospheric pollutant sources, and the levels in the Eastern
Mediterranean cities including Cairo. The annual sectoral distribution of pollutants are
calculated for Cairo based on 2005 year as the reference year. Road transport and residential
activities are important sources of PM and responsible for almost 35.9% and 53.4% of the
PM10 emissions, respectively. Industrial activities have a major part for the SO2 with 71.5%
(Kanakidou et al., 2011). Furthermore, a typical black cloud appears over Cairo and rural
regions of the Nile Delta in every fall due to biomass burning. It is found that this event is a
major contributor to the local air quality. Molina and Molina (2004) explained the black
cloud in Cairo during fall season based on the open burning of agricultural waste (mostly
burning of rice harvest by farmers to clear fields for the next harvest in rural areas of Nile
Delta). Additionally, traffic, industrial emissions and secondary aerosols was attributed to
the black cloud events. Prasat et al. (2010) indicated the long range transport of dust at high
altitudes (2.5–6 km) from Western Sahara and its deposition over the Nile Delta region. New
evidence of the desert dust transported from Western Sahara to Nile Delta during black
cloud season and its significance for regional aerosols have potential impact on the regional
climate. Recently, the European Investment Bank approved a 90,000 EURO grant in order to
investigate methods to reduce the burning of rice straw, which is thought to be one of the
potential sources of these clouds (UN and League of Arap States Report, 2006). In addition
to all, Cairo is the only city in Africa having a metro system (about 42 km length and
carrying 60,000 passengers per hour in each direction).

Air Pollution in Mega Cities: A Case Study of Istanbul
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Contribution Solid
Waste
Transport
(fuel)
Industry
(non-fuel)
Industry
(fuel)
Agricultural
Residues
(%) 30 26 23 9 6
Table 2. Relative contributions to particulate pollution from different economic activities in
Cairo (EEPP-Air, 2004).
4.3 Air quality in Cairo
Air quality in Greater Cairo is a major concern to the Government of Egypt, particularly
with regard to adverse health impacts. According to Country Cooperation Strategy (CCS)
for WHO and the Egypt Report (2010), particulate matter and lead pollution have been
recognized as the most significant pollutants threatening health in Cairo causing at least
about 6,000 premature deaths annually and about 5,000 excess cancer cases over the
lifetimes of current Cairo residents. Under this framework, PM10 is the most critical air
quality problem in Egypt. Windblown dusts particles were significantly contributed the
PM levels in Cairo and surrounding areas (EEPP-Air, 2004). A comprehensive national air
quality monitoring system has been recently established in Egypt as part of
Environmental Information and Monitoring Program and implemented with support
from the Danish Government. The monitoring system has been operational for the
measurements of common air pollutants such as SO2, NO2, CO, O3 and PM10. This is
carried out by 42 monitoring stations throughout the country with one-third of them
located in Cairo.
In recent two decades, several studies are published in the literature about the air pollution
in Cairo (Zakey& Omran, 1997; Abu-Allaban et al., 2007; Favez et al., 2008, Zakey et al.,
2008; Mahmoud et al., 2008; Safar & Labip, 2010). These studies include both anthropogenic
and natural contributions to air quality in Cairo. As an example, Zakey & Omran (1997)
showed that the dust and sand storms frequently occur specifically in spring and autumn
and hot desert cyclones known as the “Khamasin” depressions pass over the desert during
spring months. Hot and dry winds can often carry the dust and sand particulates to the city
and they increase PM levels in the Cairo atmosphere. A source attribution study was
performed by Abu-Allaban et al. (2007) where they used the chemical mass balance receptor
modeling order to examine the sources of PM10 and PM2.5 in Cairo’s ambient atmosphere.
They found that major contributors to PM10 included geological material, mobile source
emissions, and open burning. PM2.5 tended to be dominated by mobile source emissions,
open burning, and secondary species. Favez et al. (2008) examined the seasonality of major
aerosol species and their transformations in Cairo. Mahmoud et al. (2008) investigated the
origins of black carbon concentration peaks in Cairo atmosphere. Seasonal and spatial
variation of particulate matters was examined in Cairo by Zakey et al. (2008). They indicated
that the highest recorded PM10 values were found in industrial and heavy traffic locations.
The annual mean PM2.5 and PM10 are observed to be 85 and 175 μg/m3, respectively) due to
the traffic emissions and burning of waste materials. Recently, Safar&Labip (2010)
investigated health risk assessments of PM and lead in Cairo. They showed that due to the
arid climate, there is a persistent high background PM level in this area. This is one of the
reasons of the high daily PM10 levels that is above the air quality limits in the country. From
the meteorological conditions view, Cairo has very poor dispersion characteristics. Irregular
settlements, layout of tall buildings and narrow streets create a bowl effect in the city

Air Pollution – Monitoring, Modelling and Health
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environment. The high levels of lead were recorded in the major Egyptian cities.
Safar&Labip (2010) explained that the lead levels in Cairo are among the highest in the
world. The maximum annual average concentration of lead is found in the Shoubra Kheima
industrialized region due to the lead smelters in this area during the period of 1998 through
2007. The highest annual average Pb levels recorded were 26.2 and 25.4 μg/m3 at the
Shoubra Kheima and El Sahel monitoring stations, respectively, during the baseline year
(October 98 to September 99). The annual average Pb levels have been gradually decreased
when the lead smelters in the area were closed and moved to the industrial area of Abou
Zaabal. CCS (2010) report indicated that lead was completely phased out from petrol
distributed in Cairo, Alexandria and most of the cities of Lower Egypt in late 1997, and
consequently, lead concentration in the atmosphere of Cairo city centre and residential areas
gradually decreased. Surface ozone levels were also examined in Cairo. Gusten et al. (1994)
studied the ozone formation in the Greater Cairo in 1990. The peak values of 120 ppb and
daily mean value of 50 ppb throughout the year indicate a substantial contribution of
photochemistry to the ozone content of the atmosphere. It is estimated that the ozone is
produced predominantly over the industrial area in the north and in the centre of Cairo and
transported southward by the prevailing northerly winds. Contrary to many urban areas in
Europe and in North America, fairly high average ozone levels of 40 ppb are observed
during the night throughout the spring and the summer. This may imply that health
hazards and crop damage may be higher in the greater Cairo area than in Central Europe.
Recently, Mi (2009) examined the diurnal, seasonal and weekdays-weekends variations of
ground level ozone concentrations in an urban area in Greater Cairo (Haram, Giza). He
found that the daytime (8-h) mean values of wintertime and summertime O3 were 44 ppb
and 91 ppb, respectively. Besides, he reported that the highest levels of NOx were found in
winter. The concentrations of O3 precursors (NO and NO2) in weekends were lower than
those found in weekdays, whereas the O3 levels during the weekends were high compared
with weekdays.
In order to enhance the air quality in Cairo atmosphere, there are several efforts under the
new strategy by the Government such as switching to natural gas in industrial, residential
and transport sectors. Policies to remove old fleet of vehicles from the streets and to promote
public transport especially through the expansion of underground metro, enhancement of
solid waste management, banning of the open air burning of solid waste are also among the
major strategies.
5. Megacity of Delhi
Delhi (28o36’N; 77o13’E) is the second largest metropolitan in India. The name Delhi is often
used to refer both to the urban areas near the National Capital Territory of Delhi and New
Delhi, the capital of India, which is surrounded by other major urban agglomerations of
adjoining states such as Haryana and Uttar Pradesh (National Summary Report, 2010). The
National Capital Territory of Delhi is spread over an area of 1484 km2. There are three local
bodies in Delhi. Municipal Corporation of Delhi which is the major one has an area of 1397
km2 and the two small areas are New Delhi Municipal Committee and Delhi Cantonment
Board. Its population has increased from 9.4 million in 1991 to 18.9 million in 2010.
Presently, about 30% of the population lives in squatter settlements. The number of
industrial units in Delhi in 1951 was approximately 8,000. By 1991 this number had

Air Pollution in Mega Cities: A Case Study of Istanbul
89
increased to more than 125,000. The vehicular population has increased phenomenally, from
235,000 in 1975 to 2,629,000 in 1996, and closed to touch 6 million in 2011. In 1975 the
vehicular population in Delhi and Mumbai was about the same; today Delhi has three times
more vehicles than Mumbai.
5.1 Climate
The climate of Delhi is a monsoon-influenced humid subtropical climate with an extremely
hot summer, and cold winters. Delhi has relatively dry winters and has a prolonged spell of
very hot weather. Delhi usually experiences surface inversions and heavy fog events during
the winter season. This leads to restriction of dilution of the emissions from specifically
motor vehicles and episodic events in Delhi. In December, reduced visibility leads to
disruption of road, air and rail traffic. Molina & Molina (2004) explained that during
summer, large amounts of wind-blown dust carried by strong westerly winds from the Thar
Desert result in elevated PM levels. These dust storm periods are followed by the monsoon
season (July to mid-September), which is the least polluted season due to the heavy
monsoon rains that wash out the pollutants.
5.2 Air pollution sources
The major air pollution sources in Delhi are motor vehicles and industry. The number of
industrial units in Delhi increased from 8,000 in 1951 to 125,000 in 1991 while automobile
vehicles increased from 235,000 in 1975 to 4,5 million in 2004 (Government of India, 2006).
The vehicular pollution contributes 67% of the total air pollution load (approx.3 Mt per day)
in Delhi and its sharing is rapidly growing (Narain & Krupnick, 2007). The 25% of air
pollution is generated by industry and coal based thermal power plants. The three power
plants in Delhi generate approximately 6,000 Mt of fly ash per day. Industrial effluent load
is about 320 Mt per day. Municipal solid waste generation is also estimated to be 5,000 Mt
per day.
5.3 Air quality in Delhi
Delhi is the fourth most polluted megacity in the world. Air quality in Delhi is poor and
airborne concentrations of major air pollutants frequently exceed National Ambient Air
Quality Standards (NAAQS) set by India’s Central Pollution Control Board (CPCB) (The
Ministry of Environment and Forests, National Ambient Air Quality Standards 2009) A
number of studies have analyzed air pollution data for Delhi. Delhi’s annual mean PM10
concentration is highest among major Asian cities, and was between three and four times
the Indian standard during 2001–2004 (HEI, 2004). A summary of PM10, PM2.5, NO2, and
SO2 levels for different stations (background, residential, industry and kerbside) and
different seasons (winter, post monsoon, and summer) in Delhi is given in Table 3. As
seen in Table 3, almost at all locations and in all seasons, standards of PM10 and PM2.5
have been exceeded (except for the industrial area). Even the background locations are
highly polluted because these locations also fall within the city area and are impacted
from the city emissions. PM10 contribution is mainly originated from heavy duty diesel
vehicles.

Air Pollution – Monitoring, Modelling and Health
90
Background Residential Industry kerbside
Pollutant
/Season Wint Post-
Mon Sum Wint Post-
Mon Sum Wint Post-
Mon Sum Wint Post-
Mon Sum
PM10 355 300 232 505 671 81 546 781 229 451 941 337
PM2.5 - - 131 301 - 30 197 314 52 306 361 107
SO2 8 15 8 14 18 78 85 77 11 20 20 12
NO2 31 33 25 73 88 29 159 142 60 109 121 47
Table 3. Average air quality levels (μg/m3) in Delhi at background, residential, industry
and kerbside areas for winter, post monsoon and summer periods of 2007 (Nat.Rep., 2010).
It can also be seen that in terms of PM levels, Delhi shows highest air pollution levels during
post-monsoon. Observations at Delhi show much higher variability according to the
characteristics of the monitoring station area. NO2 levels are exceeded at the residential area
sites in Delhi (35%), NO2 levels generally exceed the ambient air quality standards at
kerbside locations, particularly during winter and post monsoon seasons at Delhi by 85 –
95%.This analysis shows that PM problem is severe and NO2 is the emerging pollutant that
requires immediate planning to control its emissions. NO2 is mainly contributed by man-
made sources such as vehicles, industry and other fuel combustion activities. Delhi exhibits
high percentage of NO2 from energy production owing to presence of power plants. Fig. 3
presents the trend of annual variation of Respirable Suspended Particulate Matter (RSPM or
PM10), SO2 and NO2 in Delhi in 2001-2008. The annual average RSPM and NO2
concentrations are increasing in Delhi while SO2 values are declining due to the low sulfur
fuel use in power plants. Other fuels consumed in domestic use and, in some cities, for
vehicles, are LPG and CNG respectively.
Fig. 3. Trends in annual average concentrations of RSPM, SO2, and NO2 in residential areas
of Delhi (National air quality standard is 60 for RSPM ,NO2 and SO2).

Air Pollution in Mega Cities: A Case Study of Istanbul
91
6. Megacity of Istanbul
6.1 Introduction
Air pollution problem in Istanbul has received wide public attention since the 1980s and has
remained the focal point among Turkey’s environmental problems. In the late 1980s and
beginning of 1990s, Istanbul has experienced significant particulate matter and sulfur
dioxide episodes due to the fossil fuel burning for domestic heating and industry. Following
the fuel switching policy, particulate matter concentrations and sulfur dioxide levels were
gradually decreased in the city. However, today the city is facing specifically secondary
particulate matter and NOx problems depending on the emission sources. In this part of this
chapter, firstly, a general description of the topography and meteorology of Istanbul,
emission sources, and the spatial and temporal variations of the pollutants, particularly
PM10 and SO2, in the city will be provided that will be followed by a description of the
recent emission inventory preparations. Surface ozone and its precursors in the city are also
discussed. Additionally, meteorological characteristics leading to air pollution episodes will
be extensively presented.
Istanbul is one of the significant and historically ancient megacities in the world with 13.2
million inhabitants and has an area of 5343 km2 covering 39 districts. The city is the center
of industry, economics, finance and culture in Turkey. Istanbul generates about 55% of
Turkey’s trade and produces 27.5% of Turkey’s national product. This lovely city has been
associated with major political, religious and artistic events for more than 2,000 years.
Recently, historical areas of the city have been added to the list of UNESCO World Heritage.
6.2 Topography and climate
Istanbul is located at 41oN and 29oE and is in the NW of Turkey’s from the Black Sea to
Marmara. The Bosphorus channel separates the city to Asian and European parts on the
direction of NNE/SSW (Fig.4). The Bosphorus connects the Sea of Marmara to the Black Sea.
The city also encompasses a natural harbor known as the Golden Horn in the northwest.
The historic peninsula in the European part of the city is built on seven hills and surrounded
by historical city walls. There are two significant hills in the city. The highest points in
Istanbul are Yakacık (420m) and Aydos (537m) hills in Kartal province and Camlıca hill
(288m) nearby the Bosphorus, on the Asian sides.
Istanbul has Mediterranean climate in temperate zone with four distinct seasons. Summer
months (June-July-August) are relatively dry and warm while winter months (December,
January, February) are mild and rainy. The lowest monthly average temperature is 6.5oC in
January and the highest monthly average temperature is 22.7oC in July. Domestic heating in
Istanbul usually starts in early-November and ends in the late March and early-April. There
are also around 124 rainy days with a total precipitation of 843 mm. Most of the rain comes
in winter season. Istanbul is humid and monthly average RH is 75%. RH exceeds 80% in
most winter months. Besides, irradiation is strong with average daily values in summer by
approximately 21 MJ/m2, and sunshine duration is 2460 hours annually. The prevailing
wind directions are north-easterly and south-westerly in winter, and northerly in summer,
especially when the Etesian system controls the weather in the region (Unal et al., 2000).
However, the prevailing wind direction varies from north northeast to northeast and south
southwest in the winter and varies from north northeast, northeast and east-northeast in the

Air Pollution – Monitoring, Modelling and Health
92
summer with moderate wind speeds. The urban area in Istanbul has continuously expanded
to the suburbs.
Fig. 4. A map of Istanbul with air quality measurement stations.
6.3 Emission sources
Emission sources in Istanbul have shown significant changes over time. While today, traffic,
industrial processes, domestic heating, road dust and biogenic emissions are the most
significant emission sources, domestic heating and industry was the major emission sources
before two decades ago in the city.
Istanbul has experienced a complicated period from an ancient metropolis to a sprawling
megacity, growing from just over 2 million inhabitants in 1970 to 13.2 million today.
However, due to the migration from the other cities its population has increased more than
six fold between 1970 and 2010 (Tayanc et al., 2009). Rapid urbanization and development of
society and economy, with the increased migration from the less developed regions of the
country at the end of the 1980s caused a significant increase in the population and an
expansion of the built-up areas in the city. Not only the rapid increase of the urban
population due to influx of the people from other cities, but also the establishment of many
small and medium sized industries in and around Istanbul, caused many environmental
problems. Atimtay and Incecik (2004) extensively discussed the period of 1970-1980s. The
industrial as well as the domestic heating mostly burned fuel oil to produce energy before
1970’s. Following the energy crises of 1970’s, due to the tremendous increase in the oil
prices, the preferred fuel in the city was coal. The coal used was mostly local Turkish lignite
with high in sulfur and ash content, but low in calorific value. In those days there was not
any regulation on air pollution control. The First Environmental Law was accepted in 1983
and the first Air Pollution Control Regulation was entered in force in 1986. The very active
period involving the banning of lignite, natural gas agreement, establishing of gas
distribution company (IGDAS) and starting the operations for infrastructure followed the
regulation. IGDAŞ started to distribute natural gas on January 1992, first on the Asian side

Air Pollution in Mega Cities: A Case Study of Istanbul
93
of the city and then expanded to the metropolitan area (Atimtay&Incecik, 2004). Today 95%
of the total gas is used for domestic heating and industry purposes.
As one of the major emission sources, traffic was the secondary source in 1980s. Following
1980s the number of motor vehicles on Istanbul’s streets has increased even faster than its
population growing since 1980. It was only about 0.3 million cars in 1980, but now it is
closing three million (about 2.72 million vehicles are registered based on the 2010 figures).
Every day more than 700 new cars enter to the Istanbul streets. About 60% of these vehicles
are operated by gasoline and 40% by diesel. PM10 emissions on traffic originate from diesel
vehicles rather than the gasoline powered ones. Besides, most of the heavy vehicles, such as
buses and commercial vehicles in transport and construction sectors, are powered by the
diesel system. Furthermore, following the 1999, liquefied petroleum gas has been widely
used in traffic. Istanbul Chamber of Industry reported and Im et al., 2006; Kanakidou et al.
(2011) used that the low quality solid and liquid fuels with high sulfur content, natural gas
and LPG are the most commonly used fuel types in the industrial activities including textile,
metal, chemical, food and other industries. Istanbul is on the two transit motorways passing
over the city connections between Europe and Asia on the east-west direction by the
Bosphorus and Fatih Sultan Mehmet Bridges. The total length of roads and highways has
significantly increased from 1980s within three decades while the number of vehicles has
increased. The city traffic much more depends on the two bridges in the city. The number of
vehicles crossing the two bridges has increased approximately 25% from 2001 (120,000
vehicles) to 2010 (150,000 vehicles) (KGM, 2011). Hence, traffic emissions are elevated
significantly within the past decade. Recently, Turkey adopted the Euro 4 standards to
reduce vehicular emissions of air pollutants in the beginning of 2009. Istanbul has a metro
with 16 km long in the European side and it is still expanding. On the Asian side, a new
metro construction continues and is scheduled to be opened in 2013. Furthermore, a Bus
Rapid Transit (BRT) system established in 2009 connecting the both side of the city from far
west (Avcılar) to Sogutlucesme (Kadikoy) with about 30 km. Istanbul will be connected at
soon with an underwater tunnel. The construction is currently in progress and underwater
rail tunnel (Marmaray) will be open in 2013.
There are three industrial zones in the city for small and medium-scale industrial
operations. They are located at both sides of the city. There are two busy international
airports. One is located at the European part (Atatürk Airport) and the other is Sabiha
Gokcen Airport at the Asian part (Fig. 4). Atatürk International Airport is ranked 34th in the
busiest airports of the world with a passenger traffic of 32.1 million. Sabiha Gokcen Airport
serves many domestic and some low-fare international flights, with about 104,000 total
aircraft movements annually. Istanbul experiences frequently dust transport coming from
the Sahara. Karaca et al. (2009), Celebi et al. (2010) and Kocak et al. (2011) showed that air
parcels arriving in Istanbul in the spring months are mainly from the Sahara. Nevertheless,
even limited amounts coal is consumed for domestic heating in winter months; it causes
significant particular matter pollution problems at some residential areas in the city where
mostly illegal squatter settlements are located.
6.4 Emission inventory preparations
Emission inventory has always been a significant problem in Istanbul. In recent decade,
there were several efforts on the emission inventory preparations for Istanbul

Air Pollution – Monitoring, Modelling and Health
94
Metropolitan area. In 2005, EMBARQ and Istanbul’s Directorate General of Environmental
Protection launched an ambitious initiative to reduce air pollution in the city considering
reducing transport emissions. In addition, Istanbul Metropolitan Municipality has
developed an “Istanbul Air Quality Strategy Report” emissions inventory of air pollutants
(IBB, 2009). The local emissions inventory was based on a European Union project in the
scope of the EU Life Program has been implemented in a partnership of Istanbul
Metropolitan Municipality and Dokuz Eylül University (Elbir, 2010). In this project, local
emission inventory was prepared with 1-hour temporal and 1-km spatial resolution
within an area of 170 km by 85 km centered at the metropolitan area of Istanbul. In a
systematic way, the emission sources are broadly categorized as point, line and area
sources, covering industrial, vehicular and domestic sources respectively. Five major
pollutants consisting of particulate matter (PM10), sulfur dioxide (SO2), carbon monoxide
(CO), non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOx)
emitted through these sources were identified (IBB, 2009). As seen in Table 4, industry is
the most polluting sector for SO2 contributing to about 83% of total emissions while
domestic heating is the most polluting sector for PM10 contributing to 51% of total
emissions. Traffic is also the most polluting sector for NOx, and CO emissions with the
contributions of 89% and 68%, respectively.
Emissions (tons/year)
PM10 SO2 NOx NMVOC CO
Industry 7630 58458 9394 117 1714
Domestic Heating 13631 10983 7014 18451 123510
Traffic 5200 1016 158000 38500 270000
Total 26461 70467 154408 56968 270000
Table 4. Sectoral emissions in Istanbul (IBB, 2009).
Furthermore, in recent years, there are important efforts on higher resolution (in high spatial
(2 × 2 km2) and temporal resolutions) detailed emission inventories of anthropogenic
sources studies. Markakis et al. (2012) developed high resolution emission inventory for
2007 reference year as annual sectoral distribution of pollutants; and cited by Im et al. (2010
and 2011) and Kanakidou et al, (2011). The sectoral distributions of these emissions is
presented in Table 5. Im et al. (2010) showed that wintertime PM10 episodes can be
explained almost entirely by the local anthropogenic sources. Kocak et al. (2011) confirmed
this finding by the PMF analysis conducted on the chemical composition data provided by
Theodosi et al. (2010). The emissions are spatially allocated on the cells using a grid spacing
of 2 km over the Istanbul. The pollutants considered are NOx, CO, SOx, NH3, NMVOCs,
PM10 and PM2.5. The NMVOCs emissions are chemically speciated in 23 species based on
Olivier et al. (2002) and Visschedijk et al. (2005) source sectoral profiles (CARB, 2007). PM10
emissions were chemically speciated in organic and elemental carbon, nitrates, sulfates,
ammonium and other particles. According to Markakais et al. (2012) and Kanakidou et al.
(2011), CO and NOx are the major emissions for road transport by 83.1% and 79.4%,
respectively. Industry has also major contributer for PM10 by 64.9% and SO2 by 23.2%,
respectively. However, shipping emissions in Istanbul is gradually increasing. Because,

Air Pollution in Mega Cities: A Case Study of Istanbul
95
Bosphorus Istanbul has a busy ship traffic. Recently, there are about 60,000 ships passing
yearly from the Bosphorus channel (Kesgin and Vardar, 2001; Deniz and Durmusoglu, 2008;
Incecik et al., 2010). Kanakidou et al. (2011) presents significant contribution of shipping to
SO2 emissions by 17.6% and NOx by 9.5 and PM10 by 3.1%.
CO NOx SO2 NMVOC PM10
Combustion Residential 10.8 2.1 14.7 2.6 7.1
Industry 3.7 2.4 23.2 0.5 64.9
Fuel Extraction/Distribution 2.3 0.1
Solvents Use 29.8
Road Transport 83.1 79.4 2.3 44.8 17.4
Off-road machinery 2.8 4.1 0.4 3.9
Maritime 0.3 9.5 17.6 0.6 3.1
Waste 0.7 20.4 1.7
Energy 0.7 3.2 35.6 0.2 1.8
ALL (ktons) 437 305 91 77 61
Table 5. Sectoral distribution (%) of annual anthropogenic emissions in Istanbul (Kanakidou
et al., 2011).
6.5 Air quality in Istanbul
6.5.1 Monitoring network
The first air pollution monitoring network was designed to measure SO2 and suspended
particulate matter (TSP) concentrations in the air in 1985 with 7 stations in the city by the
Ministry of Health (Hifzisihha Institute). The network provided daily SO2 and TSP
measurements. In this network, daily values of TSP concentrations were measured by the
reflectivity method and SO2 concentrations were measured with the West-Geake method. In
mid-1989, 10 more stations were established in the city. In 1998, the Greater Istanbul
Municipality established a separate air pollution monitoring network in the city. The new
network system consists of 10 measuring sites located in residential, commercial and
industrial parts of the city. The new network measures air pollution parameters on hourly
basis. Conventional parameters of PM10, which is replaced with TSP and SO2, are measured
in all stations. CO, NOx are only measured in four stations. Surface ozone was measured at
two stations in 1999-2005 and then continued with one station. Now, O3 is being measured
at two stations in the city. However, understanding of air quality in megacities requires high
spatial resolution of the monitoring network. For this purpose, in frame of a new European
Project (SIPA), about 36 stations including urban, semi urban and rural are being launched
in Istanbul and Marmara areas.
6.6 Temporal and spatial variation of air quality
The first measurements showed that Istanbul has a serious air pollution problem due to
domestic heating, industry and traffic (Incecik, 1996; Tayanc, 2000; Topcu et al.,2001). The
pollution was more severe especially in the regions of densely populated settlements.
Uncontrolled expansion of the city in 1980s also caused severe air pollution problems in

Air Pollution – Monitoring, Modelling and Health
96
certain areas. City regulations banning usage of less efficient, poor-quality lignite for heating
purposes was inadequate. Fig.5 presents the first results of the measurements as annual
average SO2 and TSP concentrations in the city. As can be seen in the figure, both SO2 and
TSP levels were much higher than the air quality standards and WHO guidelines.
Fig. 5. Annual mean values of daily SO2 and TSP concentrations in Istanbul for the polluted
period 1985-1994.
Incecik (1996) extensively examined the air quality levels and atmospheric conditions
leading to air pollution episodes in winter months of 1985-1991 periods. Incecik (1996)
showed that anticyclonic pressure patterns and lower surface wind speeds lead to
unfavorable conditions for air pollution potential over the city. Poor quality fuel used in the
city was the major reason of the dramatic levels of SO2 and TSP in the winter months.
Furthermore, he examined the ratios of January/July SO2 and TSP concentrations during the
1985-1994 periods. The ratios for SO2 an TSP presented and increase from 1.4 to 13.6 and 2.3
to 8.8, respectively in the study period. Besides, it is shown that the higher pollutant
concentrations in cool seasons might also be related to the generally stable atmosphere,
which limits the volume of air into which emissions from the local emissions are dispersed.

Air Pollution in Mega Cities: A Case Study of Istanbul
97
The relationship between occurrence of the intense episode days and other meteorological
parameters such as inversions and light winds are seen in many cities. In Istanbul,
inversions form by radiative cooling at night or as a result of subsidence in anticyclones.
Table 6 gives the characteristics of inversions recorded from radio sounding station at
Goztepe-Istanbul in the period of November 1989 – February 1990. There are almost 16
episodes occurring in this period and the days with surface or elevated inversions almost
coincide with the episode days.
Time
LST)
Surface inversion
(day)
Elevated
inversion (day)
Mean thickness of
surface inversion (m)
November 0200 10 12 273
1400 2 13 408
December 0200 13 13 242
1400 2 23 145
January 0200 9 2 280
1400 0 9 -
Feb 0200 9 13 126
1400 3 16 171
Table 6. Frequency and depth of inversions in Istanbul during November 1989-February
1990 (Incecik, 1996).
According to Table 3, the heights of the night time surface inversions in 48% of the cases are
below 250m. Furthermore, it is found that during the episodic period, calms are about 20%
or more of the total episodic periods which are probably associated with weak synoptic
scale pressure gradient at the surface atmosphere in Istanbul.
In Istanbul, natural gas usage has just started in January 1992 in the Asian part of the city.
Hence, the city of Istanbul, particularly in European side, has faced many significant
episodic air quality problems due to the poor quality lignite usage and weak dispersion
conditions in winter periods up to mid 1990s. As an example, one of the dramatic air
pollution episodes had been experienced in 1993 winter. The catastrophic values of the SO2
and TSP were measured to be 4070 and 2662 µg/m3, respectively, on 18th of January 1993 in
the European part of the city (Batuk et al., 1997). The stagnant anticyclonic pressure
conditions continued for two days in the city and Governor of Istanbul announced the
emergency situation in the city particularly for sensible people such as older people and
babies. The schools were closed for two days following the decision in the city. Fig. 6 gives
the surface synoptic map for 18 January at 00Z. As it can be seen from this figure, a very
strong anticyclonic pressure system was established over the Central Mediterranean and
South Europe and consequently the Balkan Peninsula up to the west part of the Asia Minor
and Black Sea Balkan Peninsula. Such synoptic conditions favor the formation of an
anticyclonic subsidence inversion, which results in residential and industrial stack plumes
capping specifically in the European side of the city. Fig.7 indicates the 850 hPa map
indicating geopotential heights and temperatures. This map indicates very strong
temperature advection over Istanbul.

Air Pollution – Monitoring, Modelling and Health
98
Fig. 6. 500 hPa and surface map on 18th Jan. 1993 00Z.
Fig. 7. 850 hPa Geopotential and temperature map indicating the major episode in Istanbul
on 18th January 1993, 00Z.
A ridge covers this area and in some cases a significant warm advection are observed on
17th and 18th of January. As seen in Figures 6 and 8, high pressures were observed at
surface as well as aloft, and the lower troposphere becomes strong stable. During the night

Air Pollution in Mega Cities: A Case Study of Istanbul
99
of January 17, a surface temperature inversion was formed. On January 17, the first day of
the episode, the surface pressure was rather high over the entire Balkans and Eastern
Mediterranean. The light surface winds blew from southern directions, weak at noon and
from SW at night (Fig.9). The thermodynamic structure of the lower atmosphere during the
episode shows that during the night of 17 January, a strong surface inversion was formed
with a depth of 230 m more than 5o C in strength as result of warm advection. On that night
surface atmospheric pressure was 1028 hPa and surface winds measured at the Goztepe
meteorological stations from 17th January 00Z to 19 January 12 Z were light (~1 m/s)
throughout the night and daytime period. around 1 m/s were at the south and southwest
Fig. 8. Skew T log P diagram at 00Z on 17th Jan 1993.
directions. The pollutants (SO2 and TSP) were accumulated during the following day due to
the stagnant weather conditions. Very dramatic concentrations of SO2 and TSP (4070 and
2662 μg/m3) on 18th January 1993 were measured to be associated with very strong surface
inversion and stagnant conditions during the poor quality coal usage in the European and
west parts of Istanbul. The episode ends on January 20, when a strong low pressure system
moves over the Black Sea.

Air Pollution – Monitoring, Modelling and Health
100
Fig. 9. Surface winds at 10m on 18 January 1993 at 00Z.
The hourly concentrations of PM10 were examined by several researchers. As an example,
Karaca et al. (2005) interpreted the analyses for monthly average variations of PM10
concentrations in Istanbul. The numerical results of the study indicate that cyclonic behavior
of the time series of PM10 concentrations occurs in winter and summer times with the effect
of prevailing meteorological conditions. According to Kindap et al. (2006) Istanbul had
hourly PM10 levels observed from monitoring sites that were in excess of 300µg/m3 at
several locations in the beginning of 2000s. Attributing to predominantly westerly winds at
this period it is investigated that long-range transport is effective on elevating PM levels in
Istanbul. Following the 2000s, air quality levels for Istanbul present different characteristics
based on the changing of emission sources in the city. Fig. 10 presents the temporal variation
of the annual average concentrations of some critical pollutants following fuel switching
period in the city. In this figure, the hourly PM10, SO2 and NOx, concentrations reported over
the five year period (1 January 2005 through 31 December 2010).As seen in the figure sulfur
dioxide concentrations in the city remained below the air quality standards whereas PM10
and NO2 concentrations exceeded the air quality standards.

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101
Fig. 10. Temporal variation of annual average PM10, SO2 and NO2 concentrations (µg/m3) in
Istanbul.
In a recent study, Unal et al., (2011) assessed the PM10 data in ten monitoring stations
considering the EU PM10 standards, and to identify air-monitoring sites with similar
pollutant behavior characteristics by means of hierarchical cluster analysis and to explore
possible pollutant sources in such clusters. PM10 concentration averages over the monitoring
sites under the influence of urban traffic and residential heating greatly exceeded the EU’s
daily ambient air quality standard. As an example, PM10 data for the monitoring stations of
the metropolitan air quality monitoring network show that about 32% of the total days in 6
years (2005-2010) daily PM10 concentrations exceed the limit value of 50 µg/m3 within the
city. Istanbul yields an urban average PM10 of 58 µg/m3. The monthly means for all stations
vary in between 32-68 µg/m3 in summer and 43-87 µg/m3 in winter. Unal et al., (2011)
indicated that Kartal (Asian site) Esenler and Alibeykoy (European sites) (Fig.4), where
urban areas with high traffic and industrial activity, were seriously polluted by PM10. Many
people who live in the Kartal region might be exposed to a much higher PM10 level than the
rest of the population. Topography or the barriers in the city environment of the Kartal
might support the accumulation of the concentrations. These results indicate that higher the
PM10 concentration, the greater the risk of premature mortality from heart and lung disease
to the residents living in these locations. Celebi et al. (2010) found similar PM10 results for
these locations (Fig.11).

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102
Fig. 11. Annual variation of PM10 hourly concentrations in Istanbul citywide (Celebi et al.,
2010).
The first complete chemical composition data for PM10 levels in Istanbul has been provided
by Theodosi et al. (2010). Daily PM10 samples were collected at the Bogazici University
Campus and major ionic species as well as metals and organic and elemental carbon were
measured between November 2007 and June 2009. Fig. 12 shows the temporal variation of
major chemical species in Istanbul during the sampling period and Fig.13 shows the
contribution of aerosol species to PM10 concentrations. The seasonal variations of metallic
elements revealed that elements of mainly natural origin peak during spring, associated
with natural processes such as wind flow (Sahara dust transport), whereas elements
associated with human activities peak during winter, due to domestic heating, traffic-related
and industrial emissions. The organic to elemental carbon ratio indicates that the organic
carbon is mostly primary and that the elemental part is strongly linked to traffic. During
winter additional sources like household heating contribute to the total carbon loadings. The
water-soluble organic to organic carbon ratio is characteristic for an urban area,
demonstrating a higher ratio in the summertime, mostly due to the large fraction of
secondary (oxidized and more soluble) organic species.

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103
Fig. 12. Temporal distribution of major aerosol components in Istanbul (Theodosi et al., 2010).
Fig. 13. Annual relative contribution of aerosol species to PM10 mass (Theodosi et al., 2010).

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104
Im et al. (2010) simulated the high PM10 levels observed during 13 to 17th of January, 2008
and showed that high resolution modeling with updated anthropogenic emissions can
successfully reproduce the wintertime episodes associated with local anthropogenic
emissions. Figure 14 shows the OC/PM10 ratios simulated by Im et al. (2010) which clearly
indicate the nature of PM levels in the urban parts of the city. Around the emissions hot
spots, which are located along the two sides of the Bosphorus, the ratios are calculated to be
highest (~0.40). Figure 15 shows the origin of crustal materials from Sahara based on Kocak
et al. (2011). As seen in the figure, Algerian, Libyan and Tunisian deserts are the important
sources of natural dust affecting Istanbul, as well the north-eastern parts of Black sea region.
The analysis has been conducted based on the extensive PM10 chemical composition data
from November 2007 to June 2009 in Istanbul (Theodosi et al., 2010). Further analysis
conducted by Kocak et al. (2011) clearly showed the potential impacts of Istanbul on its
surroundings (Fig.16). The results show that Istanbul is under influence of several sources
including Balkans and Eastern European countries. On the other hand, Istanbul pollution
influences western Black Sea, Balkan counties, Levantine Basin and north-eastern Africa
countries.
Fig. 14. Spatial distributions OC/PM10 mean ratio averaged over the 5-day period between
13th to 17th of January, 2008 (Im et al., 2010).

Air Pollution in Mega Cities: A Case Study of Istanbul
105
Fig. 15. Distribution of crustal source. X: Sampling site (Istanbul), A: Algeria, L: Libya and T:
Tunisia Kocak et al. (2011).

Air Pollution – Monitoring, Modelling and Health
106
Fig. 16. Sources influencing Istanbul for a) wintertime primary sources, b) summer
secondary and natural sources, and potential impacts of Istanbul on c) wintertime primary
sources and d) summertime secondary and natural sources Kocak et al. (2011).
6.6.1 Surface ozone variations in Istanbul
Surface ozone is a secondary pollutant produced by a series of complicated photochemical
reactions involving NOx and HCs in the present of intense solar radiation. The first
measurements of surface ozone at two sites in Istanbul (Kadikoy and Aksaray as seen in
Fig.1)) were studied by Topcu & Incecik (2002 and 2003). They showed that ozone levels do
not show yet episodic values in the city. But, when meteorological conditions are favorable
such as when Istanbul and its surrounding region were dominated by an anticyclonic
pressure system, ozone levels becomes high. During conducive ozone days, southerly and
south-westerly winds with low speeds (<1m/s) influence Istanbul. Fig 17 presents the time
serious of the daily peak ozone concentrations in between 2001-2006. Im et al., (2008)

Air Pollution in Mega Cities: A Case Study of Istanbul
107
evaluated the highest ozone concentrations in Istanbul. They observed in summer periods
having sunny days and maximum temperatures above 25 °C, and the episodes were mainly
characterized by south-westerly surface winds during the day and north-easterly surface
winds during the night. A modeling study conducted by Im et al. (2011a) showed that a
NOx-sensitive ozone chemistry is more pronounced in the northern parts of the city that are
characterized by forested areas with high biogenic VOC emissions. Furthermore, the high
anthropogenic NOx emissions in the urban parts leads to response of ozone more to changes
in NOx, agreeing with the findings of Im et al. (2008).
Kadıkoy
0
100
200
300
400
2001 2002 2003 2004 2005
O3 (g/m3)
Sarachane
0
100
200
300
400
2001 2002 2003 2004 2005
O3(g/m3)
Fig. 17. Daily peak ozone concentrations measured in Aksaray (Sarachane) and Kadikoy.
Furthermore, an assessment of the wind field simulations for a case study in explaining the
ozone formation mechanism over Istanbul is performed by Anteplioglu et al., 2003. In this
study, meteorological conditions favorable for high ozone concentrations appear when
Istanbul and the surrounding region are dominated by an anticyclonic pressure system.
During the ozone favorable days, south and south-westerly winds with low wind speed
influence Istanbul. In addition to the examining of the available monitoring air quality data
in the city, surface ozone concentrations and NO, NO2 were measured first time at three
different sites one is on the island (Prince’s Island or Büyükada) as background site; semi
urban site, Kandilli just over the Bosphorus and as a nearby major high way site (Goztepe
DMO). Figures 18a,b and 19a,b present the time serious of the data for the major high way
and background stations (Incecik et al., 2010). The assessment of meteorological variables
has shown that the production and destruction of the surface ozone was highly related to
temperature and wind speeds. In urban and rural areas emissions of NO decrease ozone
concentrations in the absence of solar radiation due to the reaction O3, NO, NO2 and NOx.
Conversely, O3 concentrations show comparatively less diurnal variability in rural areas due
to the absence of high NOx emission sources.

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Fig. 18a. Hourly ozone concentrations for Goztepe (on major highway) air quality station,
from July 20, 2007 to December 31, 2009.
Fig. 18b. Hourly NOx concentrations for Goztepe (on major highway) air quality station,
from July 20, 2007 to December 31, 2009.

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109
Fig. 19a. Hourly ozone concentrations for Princes’s Island Air Quality Station, from January
9, 2008 to 31 December, 2009.
Fig. 19b. Hourly NOx concentrations for Princes’s Island Air Quality Station, from January 9,
2008 to 31 December, 2009.
Im et al. (2011b) simulated the summertime ozone concentrations in the Eastern
Mediterranean, evaluating the contribution of the physical and chemical process to the
simulated ozone levels. The results showed that for Istanbul, due to the high NOx emissions,
chemistry is a sink by 34% in the surface layer and 45% in the whole PBL. By horizontal
(28%) and vertical transport (22%), Istanbul receives ozone. For the precursors of ozone
(NOx and VOCs), Istanbul is a sink in terms of transport, leading to transport of these
species to downwind locations to produce ozone. Fig.20 shows the simulated surface ozone
and NOx concentrations in the area. As seen in the Fig. 20a, Istanbul is characterized by low
ozone concentrations (~19 ppb) due to the high NOx (Fig.20b)).

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Fig. 20. Simulated levels of surface a) ozone and b) NOx mixing ratios in Istanbul averaged
over 1-15 June, 2004 (Im et al., 2011b).
6.7 Concluded remarks for Istanbul
As a summary, Istanbul had experienced many episodic air pollution events. One is very
dramatic happened in January 1993. It is similar to a small scale London smog event.
Following these events, Istanbul Greater Municipality established several strategically
programs in Istanbul for air quality management in the beginning of 1990s. The first action
was about the strict control program for the use of poor quality lignite in domestic heating
and industry. Then fuel switching program was established in the city in 1992. It was first
started in Asian parts of the city and then gradually expanded to the citywide. Now, about
95% of the city has natural gas. On the other hand, coal combustion is still a leading factor of
the particulate emissions at residential heating even if it has a limited consumption in the
city. Due to the high natural gas prices in the country, in recent years, some parts of the
urban areas use coal instead of natural gas even if they are equipped with natural gas
system in their houses. Furthermore, periodical motor vehicle inspection stations
established at international standards in late 2008. However, traffic is still the most polluting
sector for NOx, NMVOC and CO emissions. Surface ozone levels are not elevated but
depending on the increasing number of the motor vehicles, ozone potential is developing in
the city. Industry is the most polluting sector for both sides of the city. Finally, shipping
emissions over the Bosphorus in Istanbul is becoming serious problem. The emissions
should be strictly controlled.
7. Conclusions
Megacities in general experience elevated levels of primary pollutants such as particular
matter, carbon monoxide and sulfur dioxide whereas they influence the secondary
pollutants like ozone in their surrounding regions. Air pollution in megacities has been
influenced by many factors such as topography, meteorology, emissions from domestic
heating, industry and traffic. The level of air pollution in megacities depends on the

Air Pollution in Mega Cities: A Case Study of Istanbul
111
country’s technology and pollution control capability by air quality improving plans, using
cleaner fuels, renewable.
Megacities in developed and developing countries have different emission sources and air
quality problems. Most of the megacities in developed countries (Los Angeles, New York,
USA; Osaka, Tokyo, Japan and Paris, France) motor vehicles have been the major emission
source and PM10, PM2.5, and NO2 were the critical air quality parameters whereas, industry,
motor vehicles and residential heating were major emissions in developing countries. In
addition to the emission sources, the critical air quality parameters in megacities of
developing countries are PM10, PM2.5, NO2, SO2 and CO. Dust transport leads to serious air
quality and visibility problem in some megacities in developing countries such as Beijing
and Cairo.
Rapid urbanization has resulted in increasing urban air pollution in major cities, especially
in the developing countries. Over 90% of air pollution in cities of these countries is
attributed to vehicle emissions brought about by high number of older vehicles coupled
with low fuel quality. Increased population density causes new risks for the residents
through deteriorated environment and social problems due to the intense and complicated
interactions between economic, demographic, social political and ecological processes in
megacities.
Finally, in megacities of the developing world, in order to enhance quality of life, city
planning needs to adopt new visions and innovating management tools. One of the key
public concerns in megacities is transportation. High population density and high motor
vehicle rates need to be improved. Transport policies should consist of multiple strategies
particularly in developing countries.
8. Acknowledgements
The authors acknowledge Özkan Çapraz, Dr Huseyin Toros and Melike Celebi for their help
with graphics of this chapter.
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