A HAZARD is any agent that can cause harm or damage to life , health
, property or the environment .
Hazards can be dormant or potential, with only a theoretical
probability of harm. An event that is caused by interaction with a
hazard is called an incident . The likely severity of the undesirable
consequences of an incident associated with a hazard, combined with
the probability of this occurring, constitute the associated risk . If
there is no possibility of a hazard contributing towards an incident,
there is no risk.
Identification of hazards is the first step in performing a risk
* 1 Definition
* 2 Classification
* 2.1 Based on energy source
* 2.2 Based on origin
* 2.3 Based on effects
* 3 Disasters
* 4 Status of a hazard
* 6 Marking of hazards
* 7 See also
* 8 References
Kates (1978) defines environmental hazard as "the threat potential
posed to man or nature by events originating in, or transmitted by,
the natural or built environment". This definition includes a broader
range of hazards ranging from long term environmental deterioration
such as acidification of soils and build-up of atmospheric carbon
dioxide to communal and involuntary social hazards such as crime and
terrorism to voluntary and personal hazards such as drug abuse and
mountain climbing . Environmental hazards usually have defined or
common characteristics including their tendency to be rapid onset
events meaning they occur with a short warning time, they have a clear
source of origin which is easily identified, impact will be swift and
losses suffered quickly during or shortly after on-set of the event,
risk of exposure is usually involuntary due to location or proximity
of people to set hazard and the "disaster occurs with an intensity and
scale that justifies an emergency response" .
Hazards were grouped by Hewitt and Burton (1971) according to their
characteristics. These were factors related to geophysical events
which were not process specific. They were:
* Areal extent of damage zone
* Intensity of impact at a point
* Duration of impact at a point
* Rate of onset of the event
Predictability of the event
In defining hazard it is important to distinguish between natural
hazards which may be defined as "extreme events that originate in the
biosphere, hydrosphere, lithosphere or atmosphere" or "a potential
threat to humans and their welfare" which include earthquake,
landslide, hurricane and tsunamis and technological and man made
hazards including explosions, release of toxic materials, episodes of
severe contamination , structural collapses, and transportation,
construction and manufacturing accidents etc. There is also a
distinction to be made between rapid onset natural hazards,
technological hazards and social hazards which are described as being
of sudden occurrence and relatively short duration, and the
consequences of environmental degradation such as desertification and
drought, (McGuire, et al., 2002).
In defining hazard, whether it be of natural or anthropogenic origin,
Keith Smith argues that what may be defined as a natural hazard is not
in fact a hazard unless there is the presence of humans to make it a
hazard and that it is merely an event of scientific interest. In this
sense the environmental conditions we may consider hostile or
hazardous can really be seen as neutral in that it is our perception,
human location and actions which identify resources and hazards with
the range of natural events. In this regard human sensitivity to
environmental hazards is a combination of both physical exposure
(natural and/or technological events at a location related to their
statistical variability) and human vulnerability (in regard to social
and economic tolerance of the same location).
Keith Smith states that natural hazards are best seen in an
ecological framework in order to distinguish between natural events as
natural hazards. He says "natural hazards, therefore, result from the
conflict of geophysical processes with people and they lie at the
interface what has been called the natural events system and the human
interface system." He says that "this interpretation of natural
hazards gives humans a central role. Firstly through location, because
it is only when people and their possessions get in the way of natural
processes that hazard exists."
We can regard hazard then as a geophysical event which when it occurs
in extremes and a human factor is involved may be called risk of
hazard. In this context we can see that there may be an acceptable
variation of magnitude which can vary from the estimated normal or
average range with upper and lower limits or thresholds. In these
extremities the natural occurrence will become an event that presents
risk to the environment or people. Smith says "most social and
economic activities are geared to some expectation of the 'average'
conditions. As long as the variation of the environmental element
remains fairly close to this expected performance, insignificant
damage occurs and the element will be perceived as beneficial. However
when the variability exceeds some threshold beyond the normal band of
tolerance, the same variable starts to impose a stress on society and
become a hazard." Thus above average wind speeds resulting in a
tropical depression or hurricane according to intensity measures on
the Sapphire Simpson Scale will provide an extreme natural event or
Hazards can be classified as different types in several ways. One of
these ways is by specifying the origin of the hazard. One key concept
in identifying a hazard is the presence of stored energy that, when
released, can cause damage. Stored energy can occur in many forms:
chemical, mechanical, thermal, radioactive, electrical, etc. Another
class of hazard does not involve release of stored energy, rather it
involves the presence of hazardous situations. Examples include
confined or limited egress spaces, oxygen-depleted atmospheres,
awkward positions, repetitive motions, low-hanging or protruding
Hazards may also be classified as natural , anthropogenic , or
technological . They may also be classified as health or safety
hazards and by the populations that may be affected, and the severity
of the associated risk.
In most cases a hazard may affect a range of targets, and have little
or no effect on others. Identification of hazards assumes that the
potential targets are defined.
BASED ON ENERGY SOURCE
Biological hazard Main article: biological hazard Biological
hazards, also known as biohazards, originate in biological processes
of living organisms, and refer to agents that pose a threat to the
health of living organisms , the security of property, or the health
of the environment. The term and its associated symbol may be used as
a warning, so that those potentially exposed to the substances will
know to take precautions. The biohazard symbol was developed in 1966
by Charles Baldwin, an environmental-health engineer working for the
Dow Chemical Company on the containment products. and is used in the
labeling of biological materials that carry a significant health risk,
such as viral samples and used hypodermic needles . Biological hazards
include viruses, parasites, bacteria, food, fungi, and foreign toxins.
Many specific biological hazards have been identified. For example,
the hazards of naturally-occurring bacteria such as Escherichia coli
Salmonella , are well known as disease-causing pathogens and a
variety of measures have been taken to limit human exposure to these
microorganisms through food safety, good personal hygiene and
education. However, the potential for new biological hazards exists
through the discovery of new microorganisms and through the
development of new genetically modified (GM) organisms. Use of new GM
organisms is regulated by various governmental agencies. The US
Environmental Protection Agency
Environmental Protection Agency (EPA) controls GM plants that produce
or resist pesticides (i.e. Bt corn and Roundup ready crops ). The US
Food and Drug Administration (FDA) regulates GM plants that will be
used as food or for medicinal purposes. Biological hazards can include
medical waste or samples of a microorganism , virus or toxin (from a
biological source) that can affect health . Many biological hazards
are associated with food, including certain viruses , parasites ,
fungi , bacteria , and plant and seafood toxins . Pathogenic
Salmonella are common foodborne biological hazards.
The hazards from these bacteria can be avoided through risk mitigation
steps such as proper handling, storing , and cooking of food. Disease
in humans can come from biological hazards in the form of infection by
bacteria, antigens, viruses, or parasites.
Chemical hazard Main
Chemical hazard See also: poison A chemical can be
considered a hazard if by virtue of its intrinsic properties it can
cause harm or danger to humans, property, or the environment. Health
hazards associated with chemicals are dependent on the dose or amount
of the chemical. For example, iodine in the form of potassium iodate
is used to produce iodised salt . When applied at a rate of 20 mg of
potassium iodate per 1000 mg of table salt, the chemical is beneficial
in preventing goiter , while iodine intakes of 1200–9500 mg in one
dose have been known to cause death. Some chemicals have a cumulative
biological effect, while others are metabolically eliminated over
time. Other chemical hazards may depend on concentration or total
quantity for their effects. A variety of chemical hazards (e.g.
atrazine , etc.) have been identified. However, every year companies
produce more new chemicals to fill new needs or to take the place of
older, less effective chemicals. Laws, such as the Federal Food, Drug,
and Cosmetic Act and the
Toxic Substances Control Act
Toxic Substances Control Act in the US,
require protection of human health and the environment for any new
chemical introduced. In the US, the EPA regulates new chemicals that
may have environmental impacts (i.e. pesticides or chemicals released
during a manufacturing process), while the FDA regulates new chemicals
used in foods or as drugs. The potential hazards of these chemicals
can be identified by performing a variety of tests prior to the
authorization of usage. The amount of tests required and the extent to
which the chemicals are tested varies, depending on the desired usage
of the chemical. Chemicals designed as new drugs must undergo more
rigorous tests that those used as pesticides. Some harmful chemicals
occur naturally in certain geological formations, such as radon gas or
arsenic . Other chemicals include products with commercial uses, such
as agricultural and industrial chemicals, as well as products
developed for home use. Pesticides, which are normally used to control
unwanted insects and plants, may cause a variety of negative effects
on non-target organisms.
DDT can build up, or bioaccumulate, in birds,
resulting in thinner-than-normal egg shells which can break in the
nest. The organochlorine pesticide dieldrin has been linked to
Parkinson\'s disease . Corrosive chemicals like sulfuric acid , which
is found in car batteries and research laboratories, can cause severe
skin burns. Many other chemicals used in industrial and laboratory
settings can cause respiratory, digestive, or nervous system problems
if they are inhaled, ingested, or absorbed through the skin. The
negative effects of other chemicals, such as alcohol and nicotine ,
have been well documented.
Mechanical hazard Main article:
Mechanical hazard Further information:
Traffic accident and Road
safety A mechanical hazard is any hazard involving a machine or
industrial process. Motor vehicles, aircraft, and air bags pose
mechanical hazards. Compressed gases or liquids can also be considered
a mechanical hazard.
Hazard identification of new machines and/or
industrial processes occurs at various stages in the design of the new
machine or process. These hazard identification studies focus mainly
on deviations from the intended use or design and the harm that may
occur as a result of these deviations. These studies are regulated by
various agencies such as the Occupational
Safety and Health
Administration and the National Highway Traffic
Physical hazard Main article:
Physical hazard A physical
hazard is a naturally occurring process that has the potential to
create loss or damage. Physical hazards include earthquakes , floods ,
and tornadoes . Physical hazards often have both human and natural
Flood problems can be affected by the natural elements of
climate fluctuations and storm frequency, and by land drainage and
building in a flood plain , human elements. Another physical hazard,
X-rays , naturally occur from solar radiation , but have also been
utilized by humans for medical purposes; however, overexposure can
lead to cancer , skin burns , and tissue damage . Psychosocial
hazard Main article:
Psychosocial hazard Psychological or
Psychosocial hazards are hazards that affect the psychological
well-being of people, including their ability to participate in a work
environment among other people. Psychosocial hazards are related to
the way work is designed, organized and managed, as well as the
economic and social contexts of work and are associated with
psychiatric, psychological and/or physical injury or illness. Linked
to psychosocial risks are issues such as occupational stress and
workplace violence which are recognized internationally as major
challenges to occupational health and safety.
Ergonomic hazard Main
Ergonomic hazard Ergonomic hazards are physical conditions
that may pose risk of injury to the musculoskeletal system , such as
the muscles or ligaments of the lower back, tendons or nerves of the
hands/wrists, or bones surrounding the knees. Ergonomic hazards
include things such as awkward or extreme postures, whole-body or
hand/arm vibration , poorly designed tools, equipment, or
workstations, repetitive motion , and poor lighting . Ergonomic
hazards occur in both occupational and non-occupational settings such
as in workshops, building sites, offices, home, school, or public
spaces and facilities.
BASED ON ORIGIN
Natural hazards Main article:
Natural hazards such
as earthquakes , floods , volcanoes and tsunami have threatened
people, society, the natural environment, and the built environment ,
particularly more vulnerable people, throughout history, and in some
cases, on a day-to-day basis. According to the Red Cross , each year
130,000 people are killed, 90,000 are injured and 140 million are
affected by unique events known as natural disasters. Recent
policy-oriented work into hazard management began with the work of
Gilbert White, the first person to study engineering schemes as a
means of mitigating flooding in the US. From 1935 to 1967 White and
his colleagues led the research into flood defences, and further
collaboration on investigation was undertaken at the University of
Chicago. In December 1989, after several years of preparation, the
United Nations General Assembly adopted resolution 44/236 proclaiming
the 1990s as the International Decade for
The objective of that decade was stated in the annex of Resolution
44/236 as follows:
"…to reduce through concerted international action, especially in
developing countries, the loss of life, property damage , and social
and economic disruption caused by natural disasters, such as
earthquakes, wind-storms, tsunamis, floods, landslides , volcanic
eruptions, wildfire , grasshopper and locust infestations, drought and
desertification and other calamities of natural origin." Methods to
reduce risk from natural hazards include construction of high-risk
facilities away from areas with high risk, engineering redundancy ,
emergency reserve funds, purchasing relevant insurance, and the
development of operational recovery plans. Anthropogenic hazards
Anthropogenic hazard Hazards due to human behaviour
and activity. The social, natural and built environment are not only
at risk from geophysical hazards, but also from technological hazards
including industrial explosions , release of chemical hazards and
major accident hazards (MAHs).
Technological hazards Further
Disaster area §
Technological hazards Hazards due to
technology, and therefore a sub-class of anthropogenic hazards.
Sociological hazard Further information: Disaster_area §
Sociological_hazards Hazards due to sociological causes, also a
sub-class of anthropogenic hazards Sociological hazards include crime
, terrorist threats and war .
BASED ON EFFECTS
Health hazards Hazards affecting the health of exposed persons,
usually having an acute or chronic illness as the consequence.
Fatality would not normally be an immediate consequence. Safety
hazards Hazards affecting the safety of individuals, usually having an
injury or immediate fatality as the consequence of an incident
Economic hazards Hazards affecting property, wealth and the economy.
Environmental hazards Hazards affecting the environment, particularly
the natural environment and ecosystems.
Disaster See also:
Disaster can be defined as a serious disruption, occurring over a
relatively short time, of the functioning of a community or a society
involving widespread human, material, economic, societal or
environmental loss and impacts, which exceeds the ability of the
affected community or society to cope using its own resources.
Disaster can manifest in various forms, threatening those people or
environments specifically vulnerable. Such impacts include loss of
property, death, injury, trauma or post-traumatic stress disorder .
Disaster can take various forms, including hurricane, volcano ,
tsunami, earthquake, drought , famine , plague , disease, rail crash ,
car crash , tornado , deforestation , flooding, toxic release, and
spills (oil , chemicals ). These can affect people and the environment
on the local regional level, national level or international level
(Wisner et al., unknown) where the international community becomes
involved with aid donation, governments give money to support affected
countries' economies with disaster response and post-disaster
A disaster hazard is an extreme geophysical event that is capable of
causing a disaster. 'Extreme' in this case means a substantial
variation in either the positive or the negative direction from the
normal trend; flood disasters can result from exceptionally high
precipitation and river discharge, and drought is caused by
exceptionally low values. The fundamental determinants of hazard and
the risk of such hazards occurring is timing, location, magnitude and
frequency. For example, magnitudes of earthquakes are measured on the
Richter scale from 1 to 10, whereby each increment of 1 indicates a
tenfold increase in severity. The magnitude-frequency rule states that
over a significant period of time many small events and a few large
ones will occur. Hurricanes and typhoons on the other hand occur
between 5 degrees and 25 degrees north and south of the equator,
tending to be seasonal phenomena which are thus largely recurrent in
time and predictable in location due to the specific climate variables
necessary for their formation.
Major disaster, as it is usually assessed on quantitative criteria of
death and damage was defined by Sheehan and Hewitt (1969) having to
conform to the following criteria:
* At least 100 people dead,
* at least 100 people injured, or
* at least $1 million damage.
This definition includes indirect losses of life caused after initial
onset of the disaster such as secondary effects of, e.g., cholera or
dysentery. This definition is still commonly used but has the
limitations of number of deaths, injuries and damage (in $). UNDRO
(1984) defined a disaster in a more qualitative fashion as:
an event, concentrated in time and space, in which a community
undergoes severe danger and incurs such losses to its members and
physical appurtenances that the social structure is disrupted and the
fulfillment of all or some of the essential functions of the society
As with other definitions of disaster, this definition not only
encompasses social aspect of disaster impact and stresses potentially
caused but also focuses on losses, implying the need for an emergency
response as an aspect of disaster. It does not however set out
quantitative thresholds or scales for damage, death or injury
STATUS OF A HAZARD
Wreck on rocks off
Orchard Beach, New York , The Bronx during
the winter of 2007. Ukrainian "danger" road sign . Stop for
dangers, including traffic accidents, natural disasters or other road
Hazards are sometimes classified into three modes or statuses:
* DORMANT—The situation environment is currently affected. For
instance, a hillside may be unstable, with the potential for a
landslide , but there is nothing below or on the hillside that could
* ARMED—People, property, or environment are in potential harm's
* ACTIVE—A harmful incident involving the hazard has actually
occurred. Often this is referred to not as an "active hazard" but as
an accident , emergency , incident, or disaster .
Risk See also:
The terms "hazard" and "risk " are often used interchangeably.
However, in terms of risk assessment, these are two very distinct
terms. A hazard is any agent that can cause harm or damage to humans,
property, or the environment.
Risk is defined as the probability that
exposure to a hazard will lead to a negative consequence, or more
simply, a hazard poses no risk if there is no exposure to that hazard.
Consider the following example from David Okrent's 1980 article,
"Comment on Societal Risk":
Three people crossing the Atlantic in a rowboat face a hazard of
drowning ... Three hundred people crossing the Atlantic in an ocean
liner face the same hazard of drowning... The risk to each individual
per crossing is given by the probability of the occurrence of an
accident in which he or she drowns... Clearly the hazard is the same
for each individual, but the risk is greater for the individuals in
the rowboat than in the ocean liner.
Risk can be defined as the likelihood or probability of a given
hazard of a given level causing a particular level of loss of damage
(Alexander, 2000). David Alexander outlined the elements of risk as
populations, communities, the built environment , the natural
environment , economic activities and services which are under threat
of disaster in a given area.
Risk can be equated with a simple
equation, although it is not mathematical. The total risk according to
UNDRO 1982 is the "sum of predictable deaths, injuries, destruction,
damage, disruption, and costs of repair and mitigation caused by a
disaster of a particular level in a given area or areas.
David Alexander :13 distinguishes between risk and vulnerability
saying that "vulnerability refers to the potential for casualty ,
destruction, damage, disruption or other form of loss in a particular
element: risk combines this with the probable level of loss to be
expected from a predictable magnitude of hazard (which can be
considered as the manifestation of the agent that produces the loss)."
As hazard have varying degrees of severity the more intense or severe
the hazard, the greater vulnerability there will be as potential for
damage and destruction is increased with respect to severity of
hazard. Ben Wisner argues that risk or disaster is "a compound
function of the natural hazard and the number of people, characterised
by their varying degrees of vulnerability to that specific hazard, who
occupy the space and time of exposure to the hazard event." (Wisner,
et al., 1994).
Risk, vulnerability and hazard are the three factors or elements
which we are considering here in this pseudo equation. Another
definition of risk given by Factor analysis of information risk which
may be related to disaster is 'the probable frequency and probable
magnitude of future losses. Again this definition focuses on the
probability of future loss whereby degree of vulnerability to hazard
represents the level of risk on a particular population, built
environment or environment. The relationship between severity of
environmental hazard, probability and risk.
Hazard severity will
obviously vary it is necessary to outline threats posed by hazard.
* Hazards to people – death, injury, disease and stress
* Hazards to goods – property damage and economic loss
* Hazards to environment –loss of flora and fauna, pollution and
loss of amenity
MARKING OF HAZARDS
Hazard symbol Skull and crossbones , a common
symbol for poison and other sources of lethal danger (GHS hazard
Hazard symbols or warning symbols are easily recognisable symbols
designed to warn about hazardous materials, locations, or objects, The
use of hazard symbols is often regulated by law and directed by
standards organisations .
Hazard symbols may appear with different
colors, backgrounds, borders and supplemental information in order to
specify the type of hazard and the level of threat (for example,
toxicity classes ). Warning symbols are used in many places in lieu of
or addition to written warnings as they are quickly recognized (faster
than reading a written warning) and more universally understood, as
the same symbol can be recognized as having the same meaning to
speakers of different languages.
Hierarchy of hazard control
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Department of Geography Research Publications, Volume 6. University of
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Hazard additional terms
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