EOH3101PRINCIPLES OF

ENVIRONMENTAL HEALTH

POPULATION & URBANIZATION

DR. SHAHARUDDIN MOHD SHAM

DEPARTMENT OF ENVIRONMENTAL AND OCCUPATIONAL HEALTHFACULTY OF MEDICINE AND HEALTH SCIENCES, UPM

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Introduction

Geographical distribution of people in rural areas, towns and cities significantly influences the social, environmental and economic aspects of population growth.

Example: In 1600s, the majority of the North American population consisted of farmers in rural areas. Today, approximately 25% of people in the USA are involved in agriculture, and the other 75% live in cities.

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Urbanization – process of which people increasingly move from rural areas to densely populated cities

What qualifies as an urban area?Denmark – 250 peopleGreece – 10,000 peopleUSA – 2,500 people

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UrbanRural

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Important distinction between rural and urban areasRural areas – have occupations that involve harvesting natural resources such as fishing, logging and farming

Urban areas – most have jobs that are not directly connected with natural resources

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Difference in characteristics of the urban and rural population Urban areas are more heterogeneous

with respect to race, ethnicity, religion and socioeconomic status compared to populations in rural areas

People in urban areas tend to be younger than in the surrounding countryside. This is caused by influx of many young adults from rural areas.

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Urban and rural areas often have different proportions of males and females

Cities in developing countries tend to have more malesExample: In African cities, males migrate to the cities in search of employment, while females remain in the country and tend the farms and their children

Cities in highly developed countries often have a higher ratio of females to malesExample: Women in rural areas often have little chance of employment after graduating from high school, so they move to urban areas

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The City as an Ecosystem

The ecosystem approach is used to better understand how cities function and how they change overtime.

4 variables in urban trends and patterns – POET Population Organization Environment Technology

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PopulationRefers to the number of people

(birth, death, immigration and emigration) and the composition of the city by age, sex and ethnicity

Organization Refers to the social structure of the

city, including its economic policies, method of government and social hierarchy

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Environment Refers to both the natural

environment such as location of the city by the river or in the desert, and also the city’s physical infrastructure, including roads, bridges and buildings.

It also includes changes to the natural environment that are caused by humans, such as water and air pollution

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TechnologyRefers to human inventions that

directly affect the urban environment.

Example: aqueducts used to carry water long distances to cities in arid environments, and air-conditioning, which allows people to live in comfort in hot, humid cities.

The four variables (POET) do not function independently, they are interrelated, often in complex ways.

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Environmental problems associated with Urban Areas

Growing urban areas affect land-use pattern and destroy or fragment wildlife habitat by urban sprawl that encroaches into former forest, wetlands, deserts or agricultural land in rural areas

Example: Chicago, Boston and New Orleans in the USA are former wetlands.

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ChicagoBoston

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New Orleans before and after Katrina (2005)

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Commuting from suburban areas to city centres is a necessity for workers living in large urban areas, and since development is so spread out, automobiles has become a important tool to accomplish everyday chores. This heavy dependence on motor vehicles increases air pollution and causes other environmental problems.

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Water flow in cities are affected by covering of rainfall-absorbing soil with buildings and paved roads. It is polluted with organic wastes, motor oil, lawn fertilizers and heavy metals.

This water (called urban runoff) is cleaned up in sewage treatment plants before being discharged into nearby waterways. However, high levels of precipitation can overwhelm the treatment plants and result in the release of untreated urban runoff. This contaminates water far beyond the boundaries of the city

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High density of automobiles, factories and commercial enterprises in urban areas causes a build-up of air-borne emissions, such as particulate matter (dust), sulfur oxides, carbon oxides, nitrogen oxides and volatile organic compounds (VOC).

Urban areas in developing nations have the worst air pollution in the world.

Example: In Mexico City, the air is so polluted that schoolchildren are not allowed to play outside during much of the school year.

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Mexico City

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Urban Heat IslandCaused by the heat released by human activities which is retained by paved streets and buildings and slowly released into the atmosphere.

Cities are also warmer than the surrounding countryside.

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Environmental benefits of Urbanization

A well-planned city actually benefits the environment by reducing pollution and preserving rural areas.

Compact development Cities are designed so that tall, multiple unit

residential areas are close to shopping and jobs, all of which are connected by public transport.

Fewer parking lots and highways are needed, so there are more room for parks, open space, housing and businesses.

Compact development makes a city more livable, and more people may want to live there.

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Nagoya in Japan. This is a compact city with small businesses occupying the lower floors of its average 10-15 level commercial + residential buildings

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Urbanization trends

47% of the world’s population currently lives in urban areas. Before 2010, it will increase to more than 50%.

Percentage of people living in cities compared to rural settings currently is greater in highly developed countries (75%) than is developing countries (40%).

Most urban growth in the world is occurring in developing countries whereas highly developed countries are experiencing little urban growth.

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Although proportionately more people still live in rural areas in developing countries, urbanization has been increasing rapidly.

UN Data: 400 cities worldwide has a population of more than 1 million; 284 are in developing countries.

1950: only 3 of the 10 largest cities in the world were in developing countries; In 2000: 7 of the largest cities were in developing countries.

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Challenges faced by cities in developing countries

The faster pace of urban growth in developing countries has outstripped the limited capacity of many cities to provide basic services. It has also overwhelmed their economic growth.

The challenges faced are:

Substandard housing (slums and squatter areas) Poverty Exceptionally high unemployment Heavy pollution Inadequate or nonexistent water, sewage and waste

disposal Strain schools, medical and transportation systems

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Homelessness – shared by cities in both developed and developing countries.

This problem is more pronounced in the cities of developing countries.

In the USA, there are 300,000 to 500,000 homeless people on any given night.

In Calcutta, India, perhaps 250,000 homeless people sleep in the streets each night.

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Urban issues

Poverty Crime

Example: Understanding crime in urban and rural areas (handout)

Potential epidemics in densely populated cities Example: risk of urban yellow fever outbreaks

in Africa (handout)

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Think about this…

1. What is urbanization?2. What is the urbanization trend today in

largely rural nations?3. What are some of the problems brought

on by rapid urban growth in developing countries?

4. Which countries are the most urbanized?5. The least urbanized countries?

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Thank you for your attention !!!