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Urbanization is one of the most controversial problems of modern society. Although it is an essential process of social and economical development of humans, it also the source of the problems that people never faced before.

Anyone familiar with the world development trends knows that nearly half of the worlds population lives in urban areas and the number are expected to grow by 2% every year. Because of greater engagements in non-farm activities and driven by financial or educational needs people shifts to cities, causing the rapid growth of urban areas. Cities play not only the role of employment, shelter and service but also play the role of center of culture, education and portal to the rest of the world.

Although, cities and their ecology have a thousand years of evolving history, the term urbanization and ecology surprisingly only appeared very recently. For example, term Urbanization was born only in the middle of 19th century, when with the expansion of industry people started to move from rural to urban areas causing vast pressure on the capacity of cities. Air pollution, acid rain, and imbalance of ecology made the term ecology of urbanization more and more relevant in 20th century and made the public pay more attention to this issue. It is kind of scary to realize that this kind of important issue is only a little bit older than me.

Modern urbanization process has tons of problems, starting with insufficient housing and ending with global ecology impact. In this paper, I tried to cover a little piece of the ecology problems that urban areas are facing these days: air, water, waste and ecological footprint. The paper is designed to cover the basic ideas of ecological impact and how significant it can be if we dont realize it soon.


Everybody knows the obvious correlation between urbanization and economic development; some Asian countries rapidly developed during 70s and 80s, the time when the large movement of population from rural to urban was recorded. According to UN report, worldwide, cities produce on average 60 percent of a countrys GNP. Bangkok, for example, produces 40 percent of Thailands output, whereas only 12 percent of its population lives in this city. Cities are undoubtedly the basis for any functioning economy and it will keep remaining important in the future. As mentioned in the introduction, cities are the centers of culture and economic prosper, but the mismanagement and poor economical development can turn the cities into centers of unemployment, poverty and pollution.

As the city grows it needs more lumber, more steel, more labor and more land. They absorb the agricultural land for urban use, the forest for construction and all sorts of raw materials for growth. A city the size of San Francisco has more copper and aluminum than a medium size mine; more lumber than some countries have in their forest. Cities behave like a giant growing monster, eating and swallow everything round it, while at the same time spoiling and wasting surrounding areas. High concentration of cars and industries causes the air and water pollution, high demand produces extra wastes and high density requires more land. In many cases cities are the only cause of the instability of the sensitive ecosystem of the region.

Until recent time the false attitude was popular that only cities of developed countries has an ecology problem. Breaking point was in 1972 when UNs Stockholm conference on ecology declared that ecology of urbanization is one of the difficult problem almost in all countries, no matter where.

One of the reasons of environmental pollution in the developing countries is weak legislation enforcement. Cheap production cost, weak legislation enforcement and corrupted officials are the signs of easy money in developing countries. As a result many corporations from developed countries moved their production of hazardous and dangerous products in to third world. Instead of paying millions of dollars for cleaning and security equipments, they are enjoying a quite safe and cheap environment in hosting countries and harming environment without even bothering about it. Most of these productions usually located within the urban zones. For example, research done in Nicaragua in 1980, found the source of mercury poisoning among the population in capital city. Uncontrolled down throw of mercury by American corporation leaded to enormous poising of environment. In fact the content of mercury in the city water was 12 times higher than it was allowed in the US.


Air pollution

Under the term ecological disaster we understand that one constant system changes to another unstable system. For example, increase in average temperature on Earth leads to melting of polar ice, which can have an unpredictable consequence; or spread of the ozone hole can bring all sorts of diseases or death to a many life forms. One or all of these disasters would occur as the product of our activity if the countries wont pay enough attention to greenhouse effect of emission.

Urban air pollution is one of the most important environmental problems. High concentration of transportation, industry and people turns the city into perfect polluter of the air. According the statistical data, the main sources of air pollution are vehicle exhaust, industrial emissions, and domestic use of wood, coal and refuse for heating and cooking. But in the city the lion share of air pollution belongs to transportation. Vehicles contribute about 14% of total global air pollution but in big cities it can contribute up to 80% of the citys emission. There are about 600 million units of vehicles in the world, and every type produces about 3-4 kg of carbon dioxide, more than our nature can absorb.

In most European and North American cities, the concentrations of SO2 and Suspended Particulate Matter (SPM includes dust, fumes, mists and smoke SO2 and troposphere ozone) have decreased substantially in recent years. However, in the US every second person has a car, about 170 million cars with the population of 280 million people; high concentration of industry and transportation turned the US into one of the biggest air polluters in the world, even though the number is decreasing. The US account for 26% of the total air pollution in the world.

The problem is not only in developed countries. In many developing countries, rapid urbanization has resulted in increasing air pollution in many cities. WHO air quality guidelines are often not met and, in mega cities such as Beijing, Calcutta, Mexico City and Rio de Janeiro, high levels of Suspended Particulate Matter (SPM) prevail. The result of air and water pollution is chronic and infectious respiratory disease; water borne diseases; increased mortality rates, particularly among children; and premature deaths the highest rate being among the poor. In Cairo, the leading polluted city, there are about 10.6 million people with respiratory disorder (SEI 1999). Air pollution is not only the cause of lung disease, but also has become the cause of heard attacks, birth defects and cancer.

In developing countries, transportation is not the main source of air pollution. For example China and India together have about 600 million bicycles and much, much fewer cars. If in the US every second person has a car, in China only every 79th person has a car, so the sources of pollution are different. People move from rural to urban areas to find better job and a better life, so many cities in China have a housing problem. Because the city cant offer decent housing, people live in small self-built shelters and usually heating and cooking is done by burning a very low quality coal, because it is the only cheap source of energy. Beijing is one of the air polluted cities in the world and because of air pollution they have a desert problem. All green plants around the city are dead and any efforts to plant new trees and grass have had a miserable result.

The geographical location plays not last role in the determination of air pollution of cities. For example, some cities in South America, which are located in high mountains have natural problem with free flow of air movement that removes polluted air. Besides, the low oxygen concentration in high mountain areas causes the partial burn of the fuel, which simply worsens the situation. For example Mexico city, the second largest city in the world, has a big problem with smog dry, smoky fogs, which consist of carbon dioxide and nitrogen dioxide. Sometimes the smog stays for few days in the city without any movement, causing enormous harm to the health of citizens of Mexico city.

Water pollution

Water pollution problems vary in severity around the world, depending on population densities, the types and amounts of industrial and agricultural development, and the number and efficiency of waste treatment systems that are used.

For a millennia, people have used water as a convenient sink into which to dump wastes. The pollution comes from many sources, including untreated sewage, chemical discharges, petroleum leaks and spills, and agricultural chemicals that are washed off or seep downward from farm fields. In one area after another, the amounts and types of waste discharged have outstripped nature's ability to break them down into less harmful elements. Pollution spoils large quantities of water which then cannot be used, or at best can be used for restricted purposes only.

A growing number of regions face increasing water stresses because more people are both polluting

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