1 Instructor: Lee Reynolds, Associate Professor Department of Engineering Technology Texas Tech University.

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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????