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 Urban and Industrial Air Quality
Assessment and Management
Greater Tehran Area (GTA), Iran
 Dr. Yousef Rashidi was director and CEO of the AQCC, the Air Quality Control Company, a subsidiary of the Municipality of Tehran. He has most recently joined the Department of the Environment (DOE) as Head of the Air and Climate Change Office. Dr. Rashidi, when at the AQCC, was the project leader of the Iranian GTA (Greater Tehran Area) case study in EUREKA E!3266 WEBAIR.
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Tehran, the capital city of Iran, with an area of around 780 km², is the most populous and the biggest city in Iran. The population of Tehran Municipality has grown from about 0.7 million in the year 1941 to about 7,230,000 in 2005. Including surrounding areas and the commuting workforce, the metroplitan area by now exceeds 12 million inhabitants. The population growth rate of Tehran has been 0.6 % in 2001 to 2005. |
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>  The metropolitan area is surrounded on the north and east side by the Alborz Mountains, one of the highest mountain ranges in Iran with its peaks above 5,000 m. Average elevation of the city itself is about 1,300 m, increasing towards the North and the posh quarters encroaching the mountain slopes. The city (Municipality of Tehran) covers and area of approximately 22 km North-South and about 35 km East-West - embedded in a 60 by 60 km primary model domain. The city area proper is divided into 22 municipality areas or districts.
The climate is mild-continental, with hot summers (mid to high thirties) and moderately cold winters (just below zero), average annual precipitation in this semi-arid zone around 200 mm, with rainfall mostly between November and April. Predominant winds are westerlies as well as, with lower frequency, NNE and SE.
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 Air Quality
Air pollution is one of the major problems in Tehran. According to the World Bank report the annual damage due to air pollution in Iran was about 7 billion USD in 2004. Also, people die in Tehran due to air pollution and related maladies. The following chart (figure 3) illustrates statistics about number of healthy and unhealthy days in Tehran from 1999 to 2005.
(see also: Abbaspour and Soltaninejad (2004) Design of an environmental assessment model on the effect of vehicle emission in greater Tehran on air pollution with economic sensitivity.
According to the international standards (adopted in Iran) only one hazardous day is permitted within a year. In Air Quality Control Company, air pollution is being modeled with AIRVIRO Grid model based on the observerd metrological data (2 stations), emission database and Tehran topography which is subject to monitoring data received from several ambient air pollution monitoring stations located in Tehran area. A topical map of air pollution dispersion is printed in several newspapers every day.
In the WEBAIR case study, the air quality forecast for the next 120 hours is generated automatically every day based on detailed prognostioc (numerical) weather forecasts based on the NCEP/NOAA GFS data (using the MM5 nested grid meteorological model system for dynamic downscaling) and dynamic emission modeling, feeding a 3D nested grid model system (CAMx) which includes full photochemistry for ozone predictions.
 Sources of Emissions
Air pollution emissions in Tehran falls into two major groups, the stationary (industrial commercial, residential) and mobile (traffic) sources; the share of mobile sources (as a total tonnage) is 89%. Vehicles are the main emissions source in this city. CO (Carbon Monoxide) and PM10 (Particulate Matter) are the two main pollutants in Tehran. For the latter, beside the combustion sources and in particular atrffic, wind entrainment from soils including the desert areas south of the city, must also be considered as important sources.
| The Table summarizes the relative and absolute (ton/year) contribution for each emission source in 2005. Mobile sources consist of: Light duty vehicles and private cars (LDV), Motorcycles, Buses (Public transportation and the other type of buses), Trucks, Minibuses and Motor-vans. According to the study performed by AQCC in 2005 in Tehran, the contribution of light duty vehicle to air pollution has been considered to be close to 50% of the mobile sources. |
| Emission t/a |
Mobile |
% |
Stationary |
% |
| CO |
1,354,652 |
99 |
18,222 |
1 |
| SO2 |
6,142 |
10 |
57,173 |
90 |
| NOx |
109,917 |
70 |
46,253 |
30 |
| THC |
155,609 |
71 |
64,761 |
29 |
| PM |
18,777 |
69 |
8,444 |
31 |
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Emission standards in IRAN
| The European standards used for light duty vehicle emissions control are also applied in Iran (Euro I, Euro II and etc.). The time table for implementation covers 2005 to 2014. (Euro 5 will enter into force in the EU in 2009). |
| Time |
2005 |
2006 |
2007 |
2008 |
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
| LDV/ HDV |
Euro II |
Euro III |
Euro IV |
| Motorcycle |
40.01 |
Euro I |
Euro II |
Euro III |
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EU Emission Standards for Passenger Cars (Category M1, excluding vehicles above 2.5 tons which have to meet N1 category standards.) in g/km. (COP: compliance of production).
Since the import of motor vehicles to Iran is very limited, most cars used in Iran are manufactured by local companies. The technology of car engines has been converted to injection system since 2003, thus all the cars manufactured in Iran are equipped with injection system and most of them have catalytic converters. However, some of drivers due to lack of control or any sanctions remove the catalytic converters in order to avoid loss of engine power due to back pressure.
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| Tier |
Implementation Date |
CO |
HC |
HC+NOx |
NOx |
| Euro 1 |
1992.07 |
2.72 |
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0.97 |
| COP |
1992.07 |
3.16 |
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1.13 |
| Euro 2 |
1996.01 |
2.20 |
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0.50 |
| Euro 3 |
2000.01 |
2.30 |
0.20 |
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0.15 |
| Euro 4 |
2005.01 |
1.00 |
0.10 |
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0.08 |
| ECE R15/04 |
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16.54 |
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5.06 |
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 Energy consumption and fuels
There are several types of fuels used in Iran (Tehran); they include:
- Petrol (normal and super)
- Diesel (two qualities with different sulfur content)
- CNG (compressed natural gas),
- LPG (liquefied petroleum gas, constituting only a very small fraction).
According to the emission inventory study results, the pollution sources in Tehran are predominately private cars using petrol: large numbers together with poor technology and low emission standards. Only a small number of cars use CNG. The unit fuel consumption (mainly petrol) is very high in Tehran. Since petrol produced (refined) in Iran is not sufficient for all customers, the fuel is being imported by the government from the United Arab Emirates, India, China, Singapore and even Switzerland. IFCO (Iranian Fuel Conservation Organization) a subsidiary of Ministry of Oil started to convert petrol vehicles to CNG by using bi-fuel systems but there are not enough CNG refuel stations in Iran.
An important problem in Iran is quality of fuel due to octane number of petrol and sulfur content in diesel fuel. The petrol distributed in Iran comes in two quality ranges, "Normal gasoline" (87 Octane) and "Super gasoline" (95-97 Octane). Also gasoline used in Iran is lead free. Diesel fuel distributed in Iran comes in two qualities according to the sulfur content: 500 ppm for UBCT usage and 7,700 ppm for other heavy duty vehicles.  Vehicle Inspection and Maintenance
Controls are being performed by a regular Road Worthiness Inspection and Maintenance system or by the Traffic police, but this is not 100% effective. Based on research performed by AQCC by a "Capture and Re-Capture" method used for movement variables (such as vehicles, fish in the river) the fleet composition was established for the 22 municipality areas of Tehran. According to the results, Peykan and Pride (Produced by Irankhodro Co. and Saipa Co.) are the most common cars in Tehran with the corresponding contributions to the mobile source emissions (a Peykan emits at more than 15 times the old, by now obsolete Euro 1 level ...)..
 There are 6 IM centers located in Tehran that car owners can test their vehicles for light, brake system, suspension system and also emission test according to the 5 gas idle method. If the cars meet the standard limit that approved by the government (5% for CO and 500 ppm for HC), IM center issues a label to stick on the front glass of vehicle. So, police can check the car whether it has been already tested or not and meets the standards or not. All the LDV cars have to do IM tests after as soon as they are two years of age.
Public transportation 
Public transportation in Tehran consists of taxi, bus, subway and minibus. Public transportation in Tehran is managed by municipality of Tehran through 3 companies:
- UBCT (United Bus Company of Tehran) for buses and minibuses,
- Taxi Co. for taxies and
- Metro Company for the subway system.
Also, private cars used as informal taxis in a "second job" can frequently be found thoughout the city.
UBCT United Bus Company of Tehran: UBCT has several makes of buses consist of MAN, Benz, Volvo and Renault that use diesel (turbo charged and natural aspirated) or CNG as fuel. According to the statistics from UBCT, by March 2006 the number of buses was 6,597 (composed of all the above models).
Taxi Company: Several types of LDVS are used as a taxi in Tehran such as Peugeot 405, Peykan, Hyundai, Samand (a car produced in Iran that uses Peugeot engine) that some of them are equipped with CNG System. Taxi services are in 5 types: Orange taxi, Terminal taxi, Airport and Railway station taxi and Tell taxi. Number of cars in the taxi system (March 2006) was 42,794.
| Metro Company: The Metro Company operating the subway system is a subsidiary of Tehran municipality. There are 3 subway lines for people transportation in Tehran. Also, there is a plan to improve services all over Tehran according to the development of the city. Systra Company is responsible for the research and transportation development plan. |
| Time |
Line 1 |
Line 2 |
Line 5 |
Network |
| Daily average |
34,5385 |
226,513 |
93,770 |
665,668 |
| Working day average |
390,528 |
256,118 |
106,026 |
752,672 |
| Cumulative |
349,513,617 |
311,597,360 |
134,413,184 |
795,524,161 |
Subway transportation statistics (trips) in 2006.
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