List three effects that an increase in urbanization can have on air quality

More than half of the world’s population lives in urban areas. Due to the ongoing urbanisation and growth of the world’s population, there will be about 2.5 billion more people added to the urban population by 2050, mainly in Africa and Asia. The world’s urban areas are highly varied, but many cities and towns are facing problems such as a lack of jobs, homelessness and expanding squatter settlements, inadequate services and infrastructure, poor health and educational services and high levels of pollution.

In this study session, you will learn about the trends in urbanisation and the causes of urban growth. You will also learn about the demographic, health, environmental and social consequences of urbanisation.

When you have studied this session, you should be able to:

5.1  Define and use correctly all of the key words printed in bold. (SAQs 5.1 and 5.2)

5.2  Describe the global and local trends in urbanisation. (SAQ 5.3)

5.3  Explain the main causes of urban growth. (SAQs 5.1 and 5.2)

5.4  Describe the main positive and negative impacts of urbanisation. (SAQ 5.4)

In Study Session 2 you learned about the overall trend in global population growth. Most of this increase is taking place in urban areas. Urbanisation is an increase in the number of people living in towns and cities. Urbanisation occurs mainly because people move from rural areas to urban areas and it results in growth in the size of the urban population and the extent of urban areas. These changes in population lead to other changes in land use, economic activity and culture. Historically, urbanisation has been associated with significant economic and social transformations. For example, urban living is linked with higher levels of literacy and education, better health, lower fertility and a longer life expectancy, greater access to social services and enhanced opportunities for cultural and political participation (UNDESA, 2014). However, urbanisation also has disadvantages caused by rapid and unplanned urban growth resulting in poor infrastructures such as inadequate housing, water and sanitation, transport and health care services.

In 1960, the global urban population was 34% of the total; however, by 2014 the urban population accounted for 54% of the total and continues to grow. By 2050 the proportion living in urban areas is expected to reach 66% (UNDESA, 2014). Figure 5.1 shows the change in the rural and urban populations of the world from 1950 through to projected figures up to the year 2050.

scientific laws are the result of testing theories and proving them to be facts.