Recently, as developed countries, many cities have become more suitable for living, with all the facilities that people need for a comfortable lifestyle. As a result, many people migrate from rural to urban areas in a process called urbanization (Wikipedia, 2009). Urbanization has become one of the most important problems facing both people and governments in most countries. An important term that has been suggested as a policy to address the problems associated with urbanization is sustainable development. Sustainable development could be defined as a balance between human needs and environmental protection (Wikipedia, 2009). This essay aims to examine the problems of urbanization and discuss how sustainable development policy can be a good solution to address them. In addition, the trial will soon focus on three main points: overpopulation, traffic jams and air pollution. First, since people have moved to cities in large numbers, cities become overcrowded. This consequence can lead to many problems, including random life and health issues. A great example of overpopulation can be found in Mexico City. Population growth in the city is estimated at over 10,000 inhabitants/km², and this number has increased due to the huge movements into the city (Bilham-Boult et al, 1999. pp2). To illustrate the situation in Mexico City, Bilham-Boult also cited “an overcrowded, polluted and chaotic city.” In terms of health issues, infectious diseases can spread between individuals, especially in areas with large numbers of people. A good illustration of this can be seen simply in the transition of the tuberculosis pathogen, which can be inhaled...... middle of article ......xford: Heinemann.Greenwood, D. , Slack, R., Puisherer, J. and Barer, M. (2007) Medical Microbiology, USA: Elsevier. Thisdell, D. (1993). Can Los Angeles kick the car habit? New Scientist, 138 (1887), 24-29.BBC. May 25, 2007 Congestion charging plan unveiled http://news.bbc.co.uk/1/hi/england/manchester/6691683.stm Accessed July 21, 2009 Stephen J. Gislason (2009) Cars, Air Pollution and Health http: //www.nutramed.com/environment/cars.htm Accessed July 26, 2009Wikipedia Encyclopedia. July 26, 2009 Urbanization http://en.wikipedia.org/wiki/Urbanization. Accessed July 20, 2009Wikipedia Encyclopedia. July 23, 2009 Sustainable developmenthttp://en.wikipedia.org/wiki/Sustainable_development. Accessed July 20, 2009Wikipedia Encyclopedia. July 14, 2009 Traffic jamshttp://en.wikipedia.org/wiki/Traffic_congestion. Seen in 23-07-2009