1 instructor: lee reynolds, associate professor department of engineering technology texas tech...
TRANSCRIPT
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Instructor:
Lee Reynolds, Associate Professor
Department of Engineering Technology
Texas Tech University
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Definitions and Theories
Sources: Harvey F. Thomas, Ph.D., CSP,
CHMM Industrial Safety and Health,
David Goetsch, Merrill Publishers, pgs. 29-39
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Learning Objectives
Know the definitions attendant to safety and health managementKnow the basic theories of accident causation
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What is Safety
“Is it safe to go into the trench?
“I’m worried about her safety harness”
“He’s not a very safe driver”
“Does that nail gun have a safety latch?”
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What is safety & health discipline?
Multi-faceted
An ill-defined
domain
Multi-discipline
http://www.life.uiuc.edu/crofts/bc-complex_site/chick-bc-complex.gif
http://www.colored-diamonds.com/page7.htm
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Safety & Health Discipline Interactions
Environmental Operations Medical Industrial
Hygiene
Safety & Health Transportation Information Systems
Facilities
Test and evaluation Legal Training
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What does safety mean? Definition of Terms
“Safety is the prevention of accidents and the mitigation of personal injury or property damage which may result from accidents.”
Mroz
This presentation is an introduction to concepts presented in text article, Landmarks in the History of Safety, pp.10-15.
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What does the term “accident” mean?
“..An accident is a potentially harmful energy flow or environmental condition that is preceded by planning or operation oversight or omissions, resulting in conditions or actions that trigger the incident…..”
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Then what is safety relative to an accident?
“Safety is a condition or state of being resulting from the modification of human behavior, and/or design of the physical environment to reduce the possibility of hazards, thereby reducing accidents.”
Strasser et al.
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Incident vs. Accident Accidental triad
1. When an unwanted energy flow occurs or a hostile environmental condition develops.
2. Barriers or controls << than adequate.
3. Persons or objects are in the energy path or exposed to the environmental condition…
The accidental triad is complete.
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Definition of terms
Approaches to Use of Barriers.
1. Barriers on the energy source.
2. Barriers on the targets (person or objects).
3. Barriers between the energy flow and the targets.
4. Separation of the flow and targets by time or space.
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Definition of Terms
Incident – an incident is not an accident--there have been no losses. The worst that has happened is a near miss. No persons or objects were in the energy flow.
You can remove the person from the energy flow or place a barrier between him and the energy flow.
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Definition of Terms We all need energy to do our
jobs and live our lives.
Then Safety can be defined as the preplanned management of energy without damaging or harmful energy flows.
You manage energy flow through people and materiel resources.
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“..the absence of adequate barriers or controls, causes losses-injury, damage, or degraded performance-to the persons or objects in the path of the energy flow or exposed to the environmental conditions..”
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“That occurrence in a sequence of events which usually produces unintended injury, death, or property damage”.
National Safety Council
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Definition of Terms
Hazard – condition or set of conditions that have the potential to produce injury and/or property damage.
Risk- probability that a hazard will be activated and produce injury or property damage and the severity of the hazard.
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Definition of Terms
Risk involves two components –
–(1) likelihood that negative situation
will occur.
–(2) severity of injury or damage if the
hazard is activated.
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Components of risk –probability and severity
http://www.murtongroup.com/images/riskmatrix.gif
Risk
Highest Risk
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Definition of Terms continued…
Loss control – accident prevention achieved through complete safety and health hazard control program.
Hazard control – developing program to recognize, evaluate, and eliminate destructive effects of hazards.
Hazards can be either human errors or workplace conditions.
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Definition of Terms continued…
Accident prevention-elimination of factors and conditions that pose hazard and risk.
Accident mitigation-direct confrontation of accident causative factors.
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Definition of Terms
Injury – damage or harm to body as result of violence, infection or other source. Illness – environmental stress resulting in abnormal physiological condition. Acute illness – immediate effectsChronic illness – long term
effects.
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Why do accidents happen?
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Theories of Accident Causation
Major theories presented include:
Domino Theory of accident causation.
Human Factors Theory of Accident Causation
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Accident/Incident Theory of Accident Causation. Epidemiological Theory of Accident Causation.Combination Theory of Accident Causation.
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Why do Employees get Hurt on the JOB?
Accident Prone?
Carelessness?
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Equipment Failure?
Hazardous Work?
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Theories of Accident Causation
Single Factor Theory
H. W. Heinrich’s Domino Theory (1932)
Study concluded that:
88% industrial accidents caused by fellow workers’ unsafe acts.
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10% by unsafe conditions.
2% unavoidable.
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Theories of Accident Causation
Heinrick’s Axioms of Industrial Safety
Injuries result from completed series of Factors, including injury itself.
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Theories of Accident Causation
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Unsafe act by person or condition not always accident ending.
i.e. near misses.
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Theories of Accident Causation
Select corrective actions by identifying cause.
Severity accidental and accident preventable.
Best quality = best accident prevention technique.
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Theories of Accident Causation
Management assume responsibility for safety.
Supervisor key in preventing industrial accidents.
Both direct and indirect costs with accidents.
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Heinrich’s Domino TheoryThree Phases
Pre-Contact Phase
Contact Phase
Post-Contact Phase
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Heinrich’s Domino Theory Theory has two central points:
Injuries caused by action of preceding factors.
Removal of central factor (unsafe act/hazardous) negates the action of preceding factors.
Prevents accidents via elimination.
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Heinrich’s Domino Theory
Five Factors Influence ALL Accidents
1) Ancestry & Social Environment2) Fault of The Person3) Unsafe Act/ Mechanical or Physical Hazard4) Accident5) Injury
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Human Factors Theory of Accidents Chain of events caused by human error.
Three factors lead to human error:
Overload.
Inappropriate response.
Inappropriate activities.
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Overload
Inappropriate
activities
Inappropriate
responseHuman errors factor
Factors that cause human errors
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Overload Inappropriate response
Inappropriate activities
•Environmental factors
•Internal factors
•Situational factors
•Detecting a hazard but not correcting it.
•Removing safeguards
•Ignoring safety
•Performing tasks without the requisite training
•Misjudging risks
Human Factors Theory
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Accident/Incident Theory Overload
Ergonomic Traps
Decision to Err
Human Error
System Failure
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Petersen’s Accident/Incident Theory
Systems failure
Overload Ergonomic Traps •Pressure
•Fatigue
•Motivation
•Drugs, alcohol
•Worry
•Incompatible workstation
•Incompatible expectations
Decision to err.
•Misjudgment of the risks
•Unconscious desire to err
•Logical decision
•Responsibility
•Training
•Policy
•Inspection
Human Error
Accident
Injury/damage
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•Perceptions
•Environmental Factors
•Susceptibility of people
Predisposition Characteristics
Situational
Characteristics
•Risk assessment by individuals
•Peer pressure
•Priorities of the supervisor
•Attitude
Epidemiological Theory
Can cause or prevent accident conditions
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Systems Theory
Person
Machine
Environment
Collect Information
Weigh Risks
Make Decisions
Task to be Performed
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System Theory of Causation
PersonsTask to be performed
Persons
Machine
Interaction
Environment
Collect information
Weigh risks
Make decision
Feedback Loop
Stress factors???
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System Theory of Causation
Firenzie recommendation factorsbefore beginning collecting, weighing,and making decisions.
Job requirements.
Worker’s abilities and limitations.
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Loss if task is attempted but fails.
Loss if task is not attempted.
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Energy-Related Accident Causation Theory
Accidents can be prevented by controlling the energy involved or changing the structures that cause the damage.
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Energy-Related Accident Causation Theory
Limit the Energy
Substitute a Safer Form of Energy
Prevent Energy Build-up
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Prevent the Release of the Energy
Provide for a Slow Release of the Energy
Channel the Release Away
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Energy-Related Accident Causation Theory
Place a Barrier on the Energy Source.
Place a Barrier Between the Energy and Person.
Place a Barrier on the Person.
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Raise the Injury or Damage Threshold.
Ameliorate the Effects.
Rehabilitate.
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Combination Theory
Often cause of accident cannot be explained by one theory.
Cause may be due to parts of several different models to varying degrees.
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Behavioral Scientists
McGregorHerzbergLikertArgyrisBlake and MoutonSkinner
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Theories of Accident CausationSummary
The domino theory of accident causation was one of the earliest developed.
The human factor theory of accident causation attributes accidents to a chain of event caused by human error.
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Theories of Accident Causation
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Theories of Accident Causation•Epidemiological theory-models for epidemiological factors and disease good for epidemiological factors and accident.
•Systems theory views accident situation as combination of person, machine and environment.
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• Combination theory claims that no one model/theory can explain all accident.
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Questions????