Managing Air Quality Information in Tehran Using GIS
Dept. of Environment -Young Researchers Club
Faculty of Environment and Energy
Science and Research Campus, Azad University
Ali A. Alesheikh
Assistant Prof., Faculty of Geodesy and Geomatics Eng.
K,N, Toosi university of Technology, Tehran, Iran
Dept. of management
Faculty of humanities science
science and research Campus, Azad University
The effects of air pollution on public health are being felt worldwide. Pollutants, such as particulates matters (PM10) and ozone; primarily resulting from emissions of oxides of nitrogen (NOx) and hydrocarbons/air toxins (HC or VOCs), destroy sensitive tissues (in people, animals and plants), impair respiratory functions, degrade building materials and deteriorate the aesthetic aspects of environment. The costs of air pollution, from health and other damages, together with public concerns, are thus prompting all governments to seek better urban air quality.
Tehran, capital of Iran, is one of the polluted cities in the region. Due to its geographical location, the ensnared condition as surrounded by mountain ranges, and also lack of perennial winds, the smoke and other particulate matters produced from the daily life do not vanish in the air. Therefore, usually there is a thick layer of aerosols and other particulate matters in the nearby atmosphere. Air pollution and its health consequences has been a major concern for both citizens, urban planners, and decision makers of this city.
This research concentrates on identifying the most dangerous air pollutant parameters in Tehran. The parameters are then measured on the field, and presented in a GIS environment. A topographic map of 1:25000 scale has been overlaid on the position of the field sites. The values are interpolated to acquire the range of pollutants in the entire area. PSI index are then used to locate the positions of the most volatile area in the city. It is found that the most polluted area city centre in which most of the elderly resides. This indicates the potential area for creating public parks. The paper elaborates on the methodologies used in detail. The results are assessed and presented in GIS. Keywords : Air pollution , Geographic Information System , Pollutant , PSI, Interpolation
The air pollution of metropolitan areas is one of the major problems of the world at present. In Tehran, Air pollution has been created by population growth and industrial development. Tehran’s air pollution is below the world standards and the government of the Islamic Republic of Iran identified the pollution as a high priority environmental and health challenge. An important cause of air pollution is the exhaust from about 1.4 million motor vehicles, including about 0.5 million motorcycles, operating in an extremely congested road space (average vehicle speeds below 18 Km/h) and 70,000 industrial units. It is known that between 65 to 70 percent of total emissions are related to urban transport operations (2). Reported average concentrations of pollutants such as carbon monoxide (CO), particulate matter (less than 10 micron diameter (PM-10)) and sulfur dioxide (SO2), in the city center in 2007, were two to three times above average levels recommended by WHO/USEPA. The growth in the number of vehicles over the last two years has made the situation even more severe .
A geographic information system (GIS) is a computer-based information system which enables to capture, model, manipulate, retrieve, analyze and present the geographically referenced data .The ArcView GIS application developed by ESRI was selected because of its relative user friendliness and its generalized use by local authorities and research institutes. In this software, a particular display of the different shapes (industries, houses and roads) are called themes and can be selected in any order, e.g. localization of industries, emission patterns, etc. These themes can be selected or sorted according to the modeler criteria, highlighting the most relevant features on individual digital maps. It is important to note, that GIS is not only used as a map viewer in the system, but more as an integrated tool to handle data from many sources. Expanded spatial dispersion of the pollutants such as CO, NO2, SO2 and PM10 which are emitted from stationary and mobile sources is so important. It is quite suitable to utilize ArcView software and its extentions for modeling the way air pollutant distributes.This research concentrates on PM10 and CO pollutants because these are critical pollutant in Tehran.
In this research GIS design concept and application of GIS in Air Quality Management are considered. Interpolation method is selected according to capability of GIS among various air pollution modeling. The researcher presents interpolation method for each pollutant. Based on theoretical studies spline approximation may lead to better results.
2.Characteristics of the study area
Tehran is located at longitude 52-25’E. and Latitude 35-43’N. The average elevation of the city is 1,100 meters above the sea level. As the capital, Tehran has been the political and official capital over the past 200 years.
It is characterized by gentle upward slopes from the south to the north and from the west to the east formed by 3500 – 4000 m high Alborz mountains in the north and east.
The difference of height between the southern area of Tehran central station and the Mehrabad International Airport (1200m above the sea) and northern part of Tajrish district (1500 m above the sea) is 300 m. Tehran is located in the southern part of the Alborz mountains and its climate is the steppe climate.
Table 1 shows logical element at the meteorological bureau of Mehrabad International Airport in Tehran.
Tehran with a day time population of 10 millions and with a metropolitan area of over 2000 square kilometers is the center of the national government and of commercial, financial, cultural and educational activities in Iran. Repetative Rapid urban expansion over the past two decades in Tehran resulted from a high population growth rate and increased rural urban migration combined with a strong tradition of centralization in the capital.
Tehran is geographically similar to Los Angeles and Mexico City, situated at an altitude of some 1,500 m and is surrounded to the east, north and west by a snow-capped mountain range. There is little wind so pollution tends to congregate above the city, trapped by the mountains and the warm air rising from the south.
Figure (1) : Teheran
3.Geographic information system
A GIS is an information system designed to work with data referenced by spatial / geographical coordinates. In other words, GIS is both a database system with specific capabilities for spatially referenced data as well as a set of operations for working with the data. It may also be considered as a higher order map.
GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable to a wide range of public and private enterprises for explaining events, predicting outcomes, and planning strategies. (3)
A Geographic Information System is a computer based system which is used to digitally reproduce and analyze the feature present on earth surface and the events that take place on it. In the light of the fact that almost 70% of the data has geographical reference as it’s denominator, it becomes imperative to underline the importance of a system which can represent the given data geographically.
A typical GIS can be understood by the help of various definitions given below:-
A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on Earth
Burrough in 1986 defined GIS as, “Set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes”
Arnoff in 1989 defines GIS as, “a computer based system that provides four sets of capabilities to handle geo-referenced data : data input
data management (data storage and retrieval) manipulation and analysis data output. ” Hence GIS is looked upon as a tool to assist in decision-making and management of attributes that needs to be analyzed spatially.
4.Map of Carbon monoxide
Carbon monoxide (CO) is a colourless, odourless and tasteless gas that is a product of the incomplete combustion of solid, liquid and gaseous carbon-based fuels. These include wood, coal, petrol, diesel, LPG, CNG kerosene and oil.
Sources of carbon monoxide concentrations in ambient air in Tehran are typically motor vehicle emissions and domestic home heating in most urban areas. Concentrations of carbon monoxide in the indoor environment from indoor sources can also pose a major health threat. High concentrations of CO indoors can occur as a result of emissions from non-vented gas cookers and heaters. Other common indoor sources of CO include solid fuel burning and smoking.(4)
Carbon monoxide impacts on health by reducing the oxygen carrying capacity of the blood. This occurs because CO binds more readily to haemoglobin than does oxygen and results in the formation of carboxyhaemoglobin (COHb), which leaves less haemoglobin available for transferring oxygen around the body.
Figure (2):CO concentration in year 2007
5.Map of Particulates(PM10)
Air has tiny solid particles or fine liquid droplets suspended within it often called particulates. Usual concentrations are invisible but high concentrations can be seen as a haze, a mist or smoke especially when accompanied by condensing water vapour.� The large majority are less than a hundreth of a millimetre across and are known as P M tens (PM10 = particle ten m icrometres = 10μm). The fraction of the PM10’s which are thought to be the most poisonous are less than 2.5 micrometres across and are called PM2.5’s. The smallest of the particulates are the ultrafine particles which are smaller than 0.1μm across (PM0.1) and often contain less than a million molecules. There are many millions of PM10’s suspended in each cubic metre of even clean air. The chemistry of suspended particulate matter is varied and depends upon the source and can contain carbon, nitrates, sulphates, metals, polycyclic aromatic hydrocarbons to name but a few. When coal or wood is burnt, many of the poisonous emissions start as vapour but quickly condense onto surfaces such as the inside surface of chimney stacks or onto the surfaces of the suspended particles. Particles are the main delivery system for many of the inhalable poisons.
PM10’s are readily inhalable and because of their small size are not filtered and penetrate deeply into the cardiovascular system where they cause damage. Those smaller than 2.5 um penetrate deeper than those closer to 10um. Mainly because of their physical properties, they have a strong association with most types of respiratory illness and even mortality. They also have a strong association with circulatory (heart disease and strokes) disease and mortality. Particles allow many chemicals harmful to human health to be carried to many of our internal organs causing a wide range of illness and mortality including cancer, especially lung cancer, brain damage and damage to the unborn child.�
Figure (3):PM-10 concentration in year 2007
discussion and Conclusion
GIS is a suitable tool for managing air quality as we have a high volume of data that depends on time and position. With time-position analyzing and identifying critical pollution position , it is possible for manager in different level to decide on localization of new industrial centers ,transfering air pollution producer in the way that they have the least effect on air pollution of Tehran ,creating area which require clean air , identifying region need to creating green space.
Utilizing specialized GIS to control air quality we can have optimum site selecting of station. Considering the effect of distribution of pollution for instance topographic data ,land use, climatologic and geographic agents and their influence on distributing of environmental pollutant we should attend to previous factor and modeling to enter this agent in GIS we must assure and accurate of above analyzes.
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