1.
What is
hazard?[i]
A hazard is an object, situation or behaviour that has
the potential to cause harm in terms of injury, ill health or damage to
property. Hazards can appear in many working circumstances. Some hazards pose
an immediate danger, while others take a longer time to materialize.
Hazards can be classified as –
Physical hazard (temperature, ionizing/non ionizing radiation,
excessive noise, electrical exposure etc.)
Mechanical hazard: created by machinery, moving parts etc.
Chemical hazards: exposure to chemicals in workplace or elsewhere.
Biological hazards: due to viruses, bacteria, fungus etc.
When we refer to hazards in relation to occupational
safety and health the most commonly used definition is - a hazard is a potential source of harm of
adverse health effect on a person or persons.
The term hazard and risk are often used
interchangeably but there is great difference between hazard and risk
Example: if there is an open manhole, then the manhole
would present a hazard where a person may fall and get hurt. If access to that
area is prevented by a physical barricading then the risk of any one falling in
manhole and getting hurt is minimised, but the open manhole – which is a
hazard, is still there.
What is a risk?
The commonly used definition is - a risk is the likelihood that a person may
be harmed or suffers adverse effects if exposed to a hazard.
2.
What is environment?[ii]
Environment is everything that is around us. It can be
living or non-living things. It includes physical, chemical and other natural
forces. Living things live in their environment. They constantly interact with
it and adapt themselves to conditions in their environment.
3.
An environmental hazard is
a substance, state or event which has the potential to threaten the surrounding
and natural environment and/or adversely affect people’s health, including
pollution and natural disasters such as storms and earthquakes.
ENVIRONMENTAL
HAZARD EVENT[iii]
Environmental
events become hazards once they threaten to affect society and/or the
environment adversely. A physical even, such as volcanic eruption, that does
not affect human beings is a natural phenomenon, but not a natural hazard. A
natural phenomenon that occurs in a populated area is hazardous event. In areas
where there are no human interests, natural phenomena do not constitute hazards
nor do they result in disasters.
MULTIPLE
HAZARDS
When
more than one hazard event impacts the same area, there arise a multiple hazard
situation. These different hazard events may occur at the same time or may be
spaced out in time.
RETURN
PERIOD
Majority
of hazards have return periods on human time-scale. Examples are five year
flood, fifty year flood and a hundred year flood. This reflects a statistical
measure of how often a hazard event of a given magnitude and intensity will
occur. The frequency is measured in terms of hazard’s recurrence interval.
For
example, a recurrence interval of 100 years for a flood suggests that in any
year, a flood of that magnitude has a 1% chance of occurring.
Such
extreme events have very low frequencies but very high magnitude in terms of
destructive capacity. This means that an event considered being a hundred year
flood would cause severe damage compared to a five-year flood.
CLASSIFICATION
OF HAZARDS
There
are many different ways of classifying hazards. One is to consider the extent
to which hazards are natural.
1.
Natural hazards: such as earthquakes or floods arise
from purely natural processes in the environment.
2.
Quasi-natural hazards: such as smog, acid rain arise
through interaction of natural processes and human activities.
3.
Technological (or manmade) hazards: such as the toxicity of pesticides
to fauna, accidental release of chemicals or radiation from a nuclear plant.
These arise directly as a result of human activities.
According to Hewitt and Burton (1971) the hazards can
be classified as follows.
1.
Natural hazard
a.
Atmospheric hazard
i.
Excess rainfall
ii.
Heavy snowfalls
iii.
High wind speeds
iv.
Extreme temperatures
v.
Hurricanes
vi.
Thunderstorms
vii.
Tornadoes etc
b. Hydrological
hazards
i.
Floods – rivers and coastal
ii.
Drought etc
c.
Geological
i.
Landslides
ii.
Avalanches
iii.
Earthquake
iv.
Volcanic eruption etc
d.
Biological
i.
Epidemic in humans
ii.
Epidemic in plants
iii.
Epidemic in animals
iv.
Locusts etc
2.
Manmade hazards
a.
Transport accidents
b. Industrial
explosions/fires
c.
Accidental release of toxic chemicals
d.
Nuclear accidents
e.
Collapse of public buildings etc
Hazards
can also be classified as
a.
Primary hazards: primary hazards are immediate and
pose direct threat to mankind or his surroundings. Example: heavy rains which
cause flooding of rivers.
b. Secondary
hazards: secondary hazards occur as a result of primary hazards. Example – dam
failure due to floods.
[iv]An environmental
hazard is a substance, state or event which has the potential to
threaten the surrounding natural environment / or adversely affect
people's health, including pollution and natural disasters such as
storms and earthquakes.
Any single or
combination of toxic chemical, biological, or physical agents in the
environment, resulting from human activities or natural processes, that may
impact the health of exposed subjects, including pollutants such as heavy
metals, pesticides, biological contaminants, toxic waste, industrial and home
chemicals.[1]
Human-made hazards while not
immediately health-threatening may turn out detrimental to man's well-being
eventually, because deterioration in the environment can produce secondary,
unwanted negative effects on the human ecosphere. The effects of water pollution may not be
immediately visible because of a sewage system that helps
drain off toxic substances. If those substances turn out to be persistent
(e.g. persistent organic pollutant), however, they
will literally be fed back to their producers via the food chain: plankton ->
edible fish -> humans. In that respect, a considerable number of
environmental hazards listed below are man-made (anthropogenic) hazards.
Hazards can be
categorized in four types:
1. Chemical
2. Physical
(mechanical, etc.)
3. Biological
4. Psychosocial.
Chemical hazards are defined
in the Globally Harmonized Systemand in the European Union chemical
regulations. They are caused by chemical substances causing significant damage to the environment. The label is
particularly applicable towards substances with aquatic toxicity. An example
is zinc oxide, a common paint
pigment, which is extremely toxic to aquatic life.
Toxicity or other hazards
do not imply an environmental hazard, because elimination by sunlight (photolysis), water (hydrolysis) or organisms
(biological elimination) neutralizes many reactive or poisonous substances.
Persistence towards these elimination mechanisms combined with toxicity gives
the substance the ability to do damage in the long term. Also, the lack of
immediate human toxicity does not mean the substance is environmentally
nonhazardous. For example, tanker truck-sized spills of substances such
as milk can cause a
lot of damage in the local aquatic ecosystems: the added biological oxygen demand causes
rapid eutrophication,
leading to anoxic conditions in the water
body.
All hazards in this
category are mainly anthropogenic although there exist a number
of natural carcinogens and chemical elements like radon and lead may turn up in
health-critical concentrations in the natural environment:
A physical hazard
is a type of occupational hazard that involves environmental hazards that can
cause harm with or without contact.
Biological hazards,
also known as biohazards, refer to biological substances that pose a threat to
the health of living organisms, primarily that of humans. This can include
medical waste or samples of a microorganism, virus or toxin (from a biological
source) that can affect human health.
Psychosocial
hazards include but aren't limited to stress, violence and other workplace stressors. Work is generally
beneficial to mental health and personal wellbeing. It provides people with
structure and purpose and a sense of identity.
[i]
https://www.safeopedia.com/definition/152/hazard.
[ii]
https://simple.wikipedia.org/wiki/Environment
[iii]
http://www.adpc.net/casita/course-materials/Mod-2-Hazards.pdf
[iv]
https://en.wikipedia.org/wiki/Environmental_hazard
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