Industrial Health & Safety

Accident Prevention and

Theories of Accident Causation

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Economic cost of accidentsEconomic cost of accidents

• 1 death RM1.2 million • 1 permanent disability RM120,000• 4% of the world’s gross domestic product is lost with the

cost of injury, death and disease through absence from work, sickness treatment, disability and survivor benefit

• Cost of one death is estimated to be 1.2 million with 1231 occupational deaths in 2009 the national loss is 1.4 billion

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Source:

Nor Ghani Md. Nor, Ahmad Zainuddin Abdullah, Radin Umar R. S. and Hussain H. (1999) Use of Exposure Control Methods to TackleMotorcycle Accidents in Malaysia. Research Report 3. Motorcycle Safety Program. Ministry of Transport, Malaysia.

Mohd Faudzi Mohd Yusoff, Nor Ghani Md. Nor and Radin Umar Radin Sohadi (2001) The Value Of Life And Accident Costing: A Willingness To Pay Study Amongst Young Motorcyclists In Malaysia. Journal of East Asia Society for Transportation Studies, Vol 4,No. 5, 275-284.

Accident Prevention

• Why do we need to learn these theories?

• At the end of any investigation, accidents are mostly attributed to human negligence/error/mistakes etc.

• So?

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Accident prevention

– I have planned carefully…..– I followed all the steps……– I can even do this job with my eyes closed…..– It comes naturally to me……– You know what you are doing…….– So nothing could go wrong right?

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Causes of Accidents?

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Unlucky?

Human Error?

Mistakes?

What else?

Current Scenario?

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Theories of Accident Causation

• Domino Theory

• Human Factors Theory

• Accident / Incident Theory

• Epidemiological Theory

• Systems Theory

• Combination Theory8

Domino Theory

• Source: http://www.hrdp-idrm.in

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Domino Theory

• Social and ancestry factors

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Domino Theory

• Fault of person (careless)

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Domino Theory

• Unsafe acts/mechanical/physical hazard

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Domino Theory

• 4th domino = Accidents

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Domino Theory

• Last domino = Injury

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Domino Theory

Two Central Points

• Injuries are caused by the actions of preceding factors.

• Removal of the central factor (unsafe act or hazardous condition) negates the action of the proceeding factors; and in doing so, prevents accidents and injuries.

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Conclusion?

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Heinrich’s Axioms of Industrial Safety

1. Injuries result from a series of preceding factors.

2. Accidents occur as the result of physical hazard or an unsafe act.

3. Most accidents are the result of unsafe behavior.

4. Unsafe acts and hazards do not always result in immediate accidents and injuries.

5. Understanding why people commit unsafe acts helps to establish guidelines for corrective actions.

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Heinrich’s Axioms of Industrial Safety

6. Injury severity largely happens by chanceand the accident that caused it is preventable.

7. Best accident prevention techniques are analogous to best quality / productivity techniques.

8. Management should assume safety responsibilities.

9. The supervisor is the key person in the prevention of industrial accidents.

10. Cost of accidents include both direct costs and indirect costs.

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Conclusion?

What can we conclude from Heinrich’s Industrial Axioms?

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Human Factors Theory

• This theory describes the a chain of events that leads to accidents ultimately caused by human error.

• Three broad factors leading to human error• Overload• Inappropriate Responses• Inappropriate Activities

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Overload

Worker’s Capacity

Task load/burden

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Overload

• Worker’s Capacity -– Natural Ability, Training,

State of Mind, – Fatigue, Stress, Physical

Condition

• Load/Burdens:• Environmental Factors -

– Noise, Climatic, Lighting, Distractions, etc

• Internal Factors -– Personal Problems,

Emotional Stress, Worry

• Situational Factors -

– Level of Risk, Unclear Instructions, Novelty, etc

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Inappropriate Responses

• Ignores a suspected hazard

• Disregards established safety procedures

• Circumvents safety devices

• Includes incompatibility with person’s workstation Size, Required Force, Reach, Feel, etc

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Inappropriate Activities

• Performing tasks without requisite training

• Misjudging the degree of risk

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Accident/Incident Theory

• Petersen’s Extension to the Human Factors Theory

• Adds new elements -– Ergonomic Traps– Decision to Err– System Failures

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Petersen’s

O verload

System Fa ilu re

In ju ry / D am age

Accident

H um an Error

E rgonom ic Traps D ecsion to E rr

Accident / Incident Theory

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Overload

•Pressures• Deadlines, Budget Factors, Peer Pressure•Fatigue•Motivation•Drugs•Alcohol•Worry

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Ergonomic Traps

• Incompatible Workstation

• Incompatible Expectations

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Decision to Err

• Misjudgment of Risks

• Unconscious Desire to Err

• Logical Decision Based on Situation / Circumstances

• Superman Syndrome (It won’t happen to me!)• - Bulletproof, Invincible, Immortal, Lucky

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System Failures

• Potential for causal relationship between managerial decisions/behaviors regarding safety

• Policies• Responsibilities• Training• Inspections• Corrective Actions• Standards

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Epidemiological Theory

• Traditional approaches focused on– accidents and resulting injuries.

• Current trend includes a broader perspective of– industrial hygiene issues.

• Industrial Hygiene concerns environmental issues that can lead to sickness, disease, impaired health.

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Epidemiological Models

• Used to study causal relationships between environmental factors and disease.

• Theory supposes these models are also appropriate for studying the casual relationships between environmental factors and accidents.

• Note: Causal NOT Correlational Relationships !!!

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Epidemiological Theory

Can cause or prevent accident conditions

PredispositionalCharacteristics

S ituationalCharacteristics

Epidem iological Theory

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Systems Theory of Causation

• System is a group of interacting and interrelated components that form a unified whole.

• Host (People) Agent (Machinery) Environment

• The likelihood of an accident occurring is determined by how these components interact.

• Changes in the patterns of interaction can increase or decrease the probability of an accident occurring.

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Firenzie’s Systems Theory

• Person/Machine/Environment

• Information Gathering

• Risks Assessment

• Decision Making

• Task Performance

– Stressors can cloud the judgment during information gathering, risk weighing, decision making processes.

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Stressors

Firenzie’s Recommendations

• Consider Five Factors - before beginning the process of information gathering, risk weighing, decision making.

• Job Requirements• Worker’s Abilities and Limitations• Gain from Successful Task Completion• Loss if Task Attempted but Results in Failure• Loss if Task is Not Attempted

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Combination Theory of Causation

• Theories and models are not necessarily reality.

• A single theory may not suit all circumstances.

• Some theories address particular problems better than other theories.

• A combination of theories and models may be the optimal approach toward problem solutions.

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