Introduction To EH

Unit 1.
Introduction to
Environmental Health
Introduction
• Health services can be categorized in to two

1. Curative health care oriented towards seeking a
cure for an existent disease or medical condition.
2. Preventive preventing the appearance of diseases

through immunization, exercise, proper eating habits
and other life style issues
Discussion points
• Under which category is an Environmental health?

• Why this course for you?
• How can you apply this course in your future career?
Definitions: Health
 The definition developed by the World Health Organization
(WHO) states
“Health is a state of complete physical, mental, and social well-
being and not merely the absence of disease or infirmity and the
ability to lead a productive life in society.”

Determinants of health can be grouped into four basic categories.
1. Hereditary or biological factors
2. Medical care
3. Life style, and
4. Environment
 Which one may be the easiest to control??

 Which one affects people’s health more strongly than any of
the other determinants??
• Public health is the science and the art of preventing disease,
prolonging life and promoting health and efficiency through
organized community efforts.
• The success of public health effort is dependent upon the

simultaneous development of all the disciplines of public
health, with the sanitation of the environment as the first
endeavor.
Definitions: Environment
 “The complex of physical, chemical, and biotic factors (as
climate, soil, and living things) that act upon an organism or
an ecological community and ultimately determine its form
and survival.”
 The term environment captures the notion of factors that are

external to the individual, as opposed to internal factors such
as genetic makeup.
Definitions: Environment
Components of the environment

Lithosphere
Biosphere
Hydrosphere Atmosphere
Environment can be divided into two categories:
(1) Natural environment
(2) Man made/Anthropogenic environment

Environmental factors that could influence health include:
I. Life support: food, water, air etc

II. Physical factors: climate, Rain fall
III.Biological factors: microorganisms, toxins, biological waste
IV. Psycho-social and economic: e.g. crowding, income level,
access to health care
V. Chemical factors: industrial wastes, agricultural wastes, air

pollution, etc
Environmental health
• Is the prevention of diseases and promotion of health by

eliminating or controlling the environmental factors, which
form links in the chain of disease transmission.
• Is the control of all those factors in man’s physical

environment, which exercise or may exercise a deleterious
effect on his physical, mental or social well-being (WHO).
Human-Environment outcomes/interactions
1. Man can affect the environment: deforestation, fire, air
pollution, noise pollution, waste dumping, radiation
pollution, etc.
2. Man can be affected by the environment: flooding, draught,

famine, disease, earthquakes, lighting etc because of the
various disturbances in the environment.
3. Man can maintain environment good relationship:

afforestation, pollution reduction, disarmament, international
conventions and legislations on environment, etc.
Environmental Impact
Environment
(Physical, biological and psychosocial)
Human activities Health of individual

“We are part of the web of life, and whatever we do to the web of life, we do to
ourselves.”
Source: Unknown
Man-environment relationships and adverse
effects
Homo Sapiens—A Suicidal Species?
• Largely as a result of human action, profound changes are

occurring in our environment.
• The basic cause of almost all of these problems is the world’s

large and growing human population, which consumes so
much energy and produces such large quantities of toxic
wastes, etc
• Environmental changes, if accompanied by economic and

political instability, could lead to the collapse of organized
health services.
What we can do for Healthy
Environment??
The Evolution of Environmental Health
 Dietary restrictions in ancient Jewish and Islamic law, such as
bans on eating pork, presumably evolved from the recognition
that certain foods could cause disease.
 Sewage and water lines known in ancient Babylonia, Egypt,

Athens, and Rome civilization dating back more than 4,000
years
 Industrialization and rapid growing Urban environment

 Crowded, dark, unventilated housing, inadequate or non existing
water supplies, stagnant pools of water, ill-functioning open sewers,
and unmuffled industrial machinery
 Thus an epidemic of cholera and typhoid in London in 1854

was terminated by the simple expedient of removing the
handle to a pump on a well located adjacent to a sewer
Dr John Snow The board street Pump: spot mapping in 1854
Water sources Vs deaths location
18
The recognition of chemical hazards

POPs(Persistent Organic Pollutants)
Chemical accidents
Cause of RH effects (miscarriage, birth defects,

CNS effects)
Integration of ecology with human health
– The concept of carrying capacity (Wackernagel and Rees,

1995)
The Forces That Drive Environmental Health
 Environmental sources 25%-30% of the global burden of

diseases
 Continued increasing release of chemicals to environment

 Continued and increasing of chronic threats: asthma, lead
poisoning, cancer, etc
 1.3 bln urban population breathes polluted air

 Disabled, mothers and children are under high threats to
environment.
The Forces That Drive Environmental Health
 WHO estimated that diarrheal diseases accounts for

approximately 3.6% of the total DALY global burden of
diseases.
 Among these 58% is attributable to unsafe water, sanitation and

hygiene, most of which is in developing countries
 More than 2/3 and ¼global population does not have access to
basic human needs: drinking water and sanitation
New global problems on the background of above
Global issues:
 Hazardous waste
 Air pollution
 Biodiversity
 Trans-boundary waste movement;
 Global warming
 Ozone depletion
 Globalization
 Bio-terrorism
The role of environmental health in public
health
• The role of environmental sanitation is to break the

chain of disease transmission
How?
• To answer this question it is essential that we

understand the mechanism of disease transmission.
Concept of Disease Causation
 Disease result from complex interaction between
man, an agent and the environment.
 From ecological point of view disease is defined as
“maladjustment of the human organism to the
environment”.
• For the development of the infectious process, six factors are
essential:
1. Etiological or a causative agent
2. A reservoir or source of infection of the causative agent
3. A mode of escape from the reservoir
4. A mode of transmission from the reservoir to new host
5. A mode of entry into the new host
6. A susceptible host
• For a person to get sick from a germ, three conditions must
exist simultaneously:
a. There must be an a etiologic agent (a germ which causes the

disease)
b. There must be a victim (man) sensitive or susceptible to that

disease
c. There must be a mode of transmission through which the a

etiologic agent gets into the man (the pathway of the agent, i.e.
the environment).
Epidemiological Triad
Agent(A)
Host(H) Environment(E)
Health
Disease
A A
Well Dis
Balanced Balanced E
H E H
• Therefore, to stop the spread of a communicable disease,
attacking the agent, protecting the host or changing the
environment can break the chain.
• The environment also plays an important role in the control of

other non-communicable disease, such as chemical poisoning
of the air, land and water, occupational disease, etc.
• In many instances of the prevention or control measures for
many of the communicable diseases, the attack at the
environmental part of the disease cycle has been the most
feasible and vulnerable of the three components: agent-host-
environment.
– i.e. it is more practicable, and comparatively more economical, to

control the mode of transmission (the pathway of the germs) from the
reservoir to the potential new host.
• Thus the role of environmental sanitation in breaking the chain

of disease transmission must be clearly understood.
• In general environmental health breaks the chain of disease
transmission through three basic strategies:
1. Promotion: targeted to behavioral changes mainly through;

housing improvement, basic sanitary provisions.
2. Prevention of communicable diseases before it happens: safe

water, safe food, latrine provisions, personal hygiene, proper
solid waste management, vector control, etc.
3. Control of communicable diseases through various

environmental interventions.
To simplify
 Role in the transmission of communicable diseases–Triads in

epidemiology
Environment
Vector
Agent Host
 Source of infection? Uni-directionality Vs bi~?

 Determinants?
 Types of prevention?
Scope of Environmental Health
Discussion questions
• Describe the types of environmental health problems

that prevail in the developing world. Give at least
three examples.
• Illustrate the types of environmental health problems

that you have in your own community.
End

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Unit 1.

• Health services can be categorized in to two

2. Preventive preventing the appearance of diseases

• Under which category is an Environmental health?

 The definition developed by the World Health Organization

“Health is a state of complete physical, mental, and social well-

ability to lead a productive life in society.”

1. Hereditary or biological factors

3. Life style, and

 Which one may be the easiest to control??

• The success of public health effort is dependent upon the

climate, soil, and living things) that act upon an organism or

an ecological community and ultimately determine its form

 The term environment captures the notion of factors that are

Components of the environment

Environment can be divided into two categories:

(1) Natural environment

(2) Man made/Anthropogenic environment

I. Life support: food, water, air etc

V. Chemical factors: industrial wastes, agricultural wastes, air

• Is the prevention of diseases and promotion of health by

• Is the control of all those factors in man’s physical

2. Man can be affected by the environment: flooding, draught,

3. Man can maintain environment good relationship:

Human activities Health of individual

• Largely as a result of human action, profound changes are

• The basic cause of almost all of these problems is the world’s

• Environmental changes, if accompanied by economic and

 Sewage and water lines known in ancient Babylonia, Egypt,

 Industrialization and rapid growing Urban environment

 Thus an epidemic of cholera and typhoid in London in 1854

The recognition of chemical hazards

Cause of RH effects (miscarriage, birth defects,

Integration of ecology with human health

– The concept of carrying capacity (Wackernagel and Rees,

 Environmental sources 25%-30% of the global burden of

 Continued increasing release of chemicals to environment

 1.3 bln urban population breathes polluted air

 WHO estimated that diarrheal diseases accounts for

 Among these 58% is attributable to unsafe water, sanitation and

• The role of environmental sanitation is to break the

• To answer this question it is essential that we

 Disease result from complex interaction between

man, an agent and the environment.

 From ecological point of view disease is defined as

“maladjustment of the human organism to the

1. Etiological or a causative agent

2. A reservoir or source of infection of the causative agent

3. A mode of escape from the reservoir

4. A mode of transmission from the reservoir to new host

5. A mode of entry into the new host

a. There must be an a etiologic agent (a germ which causes the

b. There must be a victim (man) sensitive or susceptible to that

c. There must be a mode of transmission through which the a

• The environment also plays an important role in the control of

– i.e. it is more practicable, and comparatively more economical, to

• Thus the role of environmental sanitation in breaking the chain

1. Promotion: targeted to behavioral changes mainly through;

2. Prevention of communicable diseases before it happens: safe