Hazard, Risk and Causation
Just what are hazards and risks? Typically, a hazard has been considered as anything that has the potential to do harm. However, a better definition, particularly with regard to safety science, is 'a source of potentially damaging energy'. Viner, D 1991, Accident analysis and risk control, Delphi, Carlton South.
A risk then, with respect to safety science (as opposed to its common use) is defined as "the potential for realisation of the unwanted consequences of an event". Rowe, WD 1977 An Anatomy of Risk Wiley Interscience, New York.
The following short video provides a summary of what is a hazard and a risk.
WorkSafeBC 2010, Understaning Hazards and Risks, video, June 17, viewed 26 January 2015. http://youtu.be/aRvULYpobms
Classification of hazards taking account of context and conditions:
Pryor, P 2012, 'Hazard as a Concept', In HaSPA (Health and Safety Professionals Alliance), The Core Body of Knowledge for Generalist OHS Professionals, Safety Institute of Australia, Tullamarine VIC, pp. 6-7.
Sources of energy as basis for a classification of hazards
Pryor, P 2012, 'Hazard as a Concept', In HaSPA (Health and Safety Professionals Alliance), The Core Body of Knowledge for Generalist OHS Professionals, Safety Institute of Australia, Tullamarine VIC, pp. 5-6.
And what happens when the hazards and risks of a situation aren't understood? Although a light-hearted approach (with some out-there situations), this video paints a clear picture of potential consequence.
DumbWays2Die 2012, Dumb Ways to Die, video, November 14, viewed 26 January 2015. http://youtu.be/IJNR2EpS0jw
Causation
The following is an overview of well known models of accident causation.
Heinrich's Domino Theory:
The model is based on the assumption that:
"the occurrence of a preventable injury is the natural culmination of a series of events or circumstances, which invariably occur in a fixed or logical order … an accident is merely a link in the chain".
This model proposed that certain accident factors could be thought of as being lined up sequentially like dominos. Heinrich proposed that an:
"… accident is one of five factors in a sequence that results in an injury … an injury is invariably caused by an accident and the accident in turn is always the result of the factor that immediately precedes it".
Heinrich’s five factors were:
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Social environment/ancestry
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Fault of the person
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Unsafe acts, mechanical and physical hazards
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Accident
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Injury.
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Extending the domino metaphor, an accident was considered to occur when one of the dominos or accident factors falls and has an ongoing knock-down effect ultimately resulting in an accident
Based on the domino model, accidents could be prevented by removing one of the factors and so interrupting the knockdown effect.
Text and Image:
Toft, Y, Dell, G, Klockner, K & Hutton, A 2012, 'Models of Causation: Safety', In HaSPA (Health and Safety Professionals Alliance), The Core Body of Knowledge for Generalist OHS Professionals, Safety Institute of Australia, Tullamarine VIC, pp. 4-5.
Reason's 'Swiss Cheese Model'
By analysing everyday slips and lapses, James Reason developed models of human error mechanisms. Reason went on to address the issue of two kinds of errors: active errors and latent errors. Active errors were those “where the effect is felt almost immediately” and latent errors “tended to lie dormant in the system largely undetected until they combined with other factors to breach system defences”.
Reason accepted that accidents were not solely due to individual operator error (active errors) but lay in the wider systemic organisational factors (latent conditions) in the upper levels of the organisation.
Text and Image:
Toft, Y, Dell, G, Klockner, K & Hutton, A 2012, 'Models of Causation: Safety', In HaSPA (Health and Safety Professionals Alliance), The Core Body of Knowledge for Generalist OHS Professionals, Safety Institute of Australia, Tullamarine VIC, p. 12.
Energy Damage Model
The energy damage model is based on the notion that:
“Damage (being an injury) is a result of an incident energy whose intensity at the point of contact with the recipient exceeds the damage threshold of the recipient”
In the Energy Damage Model the hazard is a source of potentially damaging energy and an accident, injury or damage may result from the loss of control of the energy when there is a failure of the hazard control mechanism. These mechanisms may include physical or structural containment, barriers, processes and procedures. The space transfer mechanism is the means by which the energy and the recipient are brought together assuming that they are initially remote from each other. The recipient boundary is the surface that is exposed and susceptible to the energy.
Derek Viner is a notable authority on this model.
Text and Image:
Toft, Y, Dell, G, Klockner, K & Hutton, A 2012, 'Models of Causation: Safety', In HaSPA (Health and Safety Professionals Alliance), The Core Body of Knowledge for Generalist OHS Professionals, Safety Institute of Australia, Tullamarine VIC, pp. 7-8.
Roll The Dice:
The following is a short video which ties together risk, hazards, consequence and ideas of causation. The video references what is known as 'Bird's Triangle', as well as relating to Heinrich's Domino Theory as foundations of a major injury.
James Smith 2014, Roll the dice Health and Safety video, video, 26 May, viewed 26 January 2015, http://youtu.be/B5_DFNXnCcE
Hazard Control
In order to effectively manage hazards, the hierarchy of hazard control should be utilised. As can be seen in the diagram below, these controls range from most to least useful, and any attempts to control an identified hazard should begin from the top of the hierarchy down.
EasyGuides Australia ND Hierarchy of Hazard Control, viewed 26 January 2015, http://www.easyguides.com.au/sitebuilder/store/large/1871/hie001.jpg