THEORIES OF ACCIDENT CAUSATION

What is your opinionconcerning the varioustheories of accidentcausation?

LEARNING OBJECTIVES

To explain all theories of accident causationTo identify the advantages and disadvantages all the accident

causation theoriesTo evaluate the right model to explain accident causation at the

workplace

THEORIES OF ACCIDENT CAUSATION

Domino Theory of Accident Causation Human Factors Theory of Accident Causation Accident/Incident Theory of Accident Causation Epidemiological Theory of Accident Causation Systems Theory of Accident Causation Combination Theory of Accident Causation Behavioral Theory of Accident Causation Drugs and Accident Causation Depression and Accident Causation Management Failures and Accident Causation Obesity and Accident Causation

INTRODUCTION

Each year, work-related accidents cost the United States almost$50 billion.

This figure includes costs associated with lost wages, medicalexpenses, insurance costs, and indi-rect costs.

The number of persons injured in industrial place accidents in atypical year is 7,128,000, or 3 per 100 persons per year.

In the workplace, there is one accidental death approximatelyevery 51 minutes and one injury every 19 seconds

DOMINO THEORY OF ACCIDENTCAUSATION

An early pioneer of accident prevention and industrial safety wasHerbert W. Heinrich, an official with the Travelers InsuranceCompany. In the late 1920s, after studying the reports of 75,000industrial accidents, Heinrich concluded that 88 percent of industrial accidents are caused by unsafe acts

committed by fellow workers. 10 percent of industrial accidents are caused by unsafe

conditions. 2 percent of industrial accidents are unavoidable.

Heinrichs Axioms of Industrial Safety

Injuries result from a completed series of factors, one of which isthe accident itself.

An accident can occur only as the result of an unsafe act by aperson and/or a physical or mechanical hazard.

Most accidents are the result of unsafe behavior by people. An unsafe act by a person or an unsafe condition does not always

immediately result in an accident/injury. The reasons why people commit unsafe acts can serve as helpful

guides in selecting corrective actions.

Heinrichs Axioms of Industrial Safety

The severity of an accident is largely fortuitous, and the accidentthat caused it is largely preventable.

The best accident prevention techniques are analogous with thebest quality and productivity techniques.

Management should assume responsibility for safety because it isin the best position to get results.

The supervisor is the key person in the prevention of industrialaccidents.

In addition to the direct costs of an accident (for example,compensation, liability claims, medical costs, and hospitalexpenses), there are also hidden or indirect costs.

Domino Theory1932 First Scientific Approach toAccident/Prevention - H.W. HeinrichIndustrial Accident PreventionIndustrial Accident Prevention

Social EnvironmentSocial Environmentand Ancestry

Fault of theFault of thePerson

(Carelessness)Unsafe ActUnsafe Act

orCondition

Accident Injury

MISTAKES OF PEOPLEMISTAKES OF PEOPLE

Ancestry and social environment. Negative character traits that may leadpeople to behave in an unsafe manner can be inherited (ancestry) or acquiredas a result of the social environment.

Fault of person. Negative character traits, whether inherited or acquired, arewhy people behave in an unsafe manner and why hazardous conditions exist.

Unsafe act/mechanical or physical hazard. Unsafe acts committed by peopleand mechanical or physical hazards are the direct causes of accidents.

Accident. Typically, accidents that result in injury are caused by falling orbeing hit by moving objects.

Injury. Typical injuries resulting from accidents include lacerations andfractures.

Heinrichs theory has two central points: (1) injuries are caused by the actionof preceding factors and (2) removal of the central factor (unsafeact/hazardous condition) negates the action of the preceding factors and, in sodoing, prevents accidents and injuries.

Heinrichs Theory

Corrective Action Sequence(The three Es)

EngineeringEducation

Enforcement

HUMAN FACTORS THEORY OFACCIDENT CAUSATION

The human factors theory of accident causation attributesaccidents to a chain of events ultimately caused by humanerror.

It consists of the following three broad factors that lead tohuman error:

overload, inappropriate response, and inappropriate activities

Human Factors Theory

OverloadEnvironmentalFactors (noise,distractions

Internal Factors(personalproblems,emotional stress)

SituationalFactors (unclearinstructions, risklevel)

InappropriateResponse

Detecting ahazard but notcorrecting it

Removingsafeguards frommachines andequipment

Ignoring safety

InappropriateActivities

Performingtasks without therequisite training

Misjudging thedegree of riskinvolved with agiven task

OVERLOAD

Overload amounts to an IMBALANCE between a persons capacity atany given time and the load that person is carrying in a given state.

A persons capacity is the product of such factors as his or her:Natural ability, Training, State of mind, Fatigue, Stress, and Physical condition.

INAPPROPRIATE RESPONSE ANDINCOMPATIBILITY

How a person responds in a given situation can cause or prevent anaccident. ( Examples)

If a person detects a hazardous condition but does nothing tocorrect it, he or she has responded inappropriately.

If a person removes a safeguard from a machine in an effort toincrease output, he or she has responded inappropriately.

If a person disregards an established safety procedure, he or shehas responded inappropriately.

The incompatibility of a persons workstation with regard to size,force, reach, feel, and similar factors can lead to accidents andinjuries.

INAPPROPRIATE ACTIVITIES

Human error can be the result of inappropriate activities. Anexample of an inappropriate activity is a person whoundertakes a task that he or she doesnt know how to do.

Another example is a person who misjudges the degree of riskinvolved in a given task and proceeds based on thatmisjudgment.

Such inappropriate activities can lead to accidents and injuries.

ACCIDENT/INCIDENT THEORY OFACCIDENT CAUSATION

The accident/incident theory is an extension of the humanfactors theory. It was developed by Dan Petersen and issometimes referred to as the Petersen accident/incident theory.

Petersen introduced such new elements as ergonomic traps, thedecision to err, and systems failures, while retaining much ofthe human factors theory.

Petersens Accident/IncidentTheory

OverloadPressure

Fatigue

Motivation

Drugs

Alcohol

Worry

Ergonomic Traps

Incompatibleworkstation (i.e.size, force, reach,feel)

Incompatibleexpectations

Decision to Err

Misjudgment ofthe risk

Unconsciousdesire to err

Logical decisionbased on thesituation

Systems FailurePolicy Inspection

Responsibility Correction

Training Standards

Human Error

Accident

Injury/Damage

A variety of pressures such as deadlines, peer pressure, and budgetfactors can lead to unsafe behavior. Another factor that caninfluence such a decision is the It wont happen to mesyndrome.

Following are just some of the different ways that systems can fail,according to Petersens theory:

Management does not establish a comprehensive safety policy. Responsibility and authority with regard to safety are not clearly

defined. Safety procedures such as measurement, inspection, correction, and

investigation are ignored or given insufficient attention. Employees do not receive proper orientation. Employees are not given sufficient safety training.

EPIDEMIOLOGICAL THEORY OFACCIDENT CAUSATION

Industrial hygiene concerns environmental factors that can leadto sickness, disease, or other forms of impaired health.

This trend has, in turn, led to the development of anepidemiological theory of accident causation.

Epidemiology is the study of causal relationships betweenenvironmental factors and disease.

Epidemiological Theory

PredispositionCharacteristics

Susceptibility of people

Perceptions

Environmental factors

SituationalCharacteristics

Risk assessment byindividuals

Peer pressure

Priorities of thesupervisor

Attitude

Can cause or preventaccident conditions

The key components are PREDISPOSITIONAL CHARACTERISTICSand SITUATIONAL CHARACTERISTICS. These characteristics, takentogether, can either result in or prevent conditions that mayresult in an accident.

For example, if an employee who is particularly susceptible topeer pressure (predispositional characteristic) is pressured byhis coworkers (situational characteristic) to speed up hisoperation, the result will be an increased probability of anaccident.

SYSTEMS THEORY OF ACCIDENTCAUSATION

This theory views a situation in which an accident may occur as a systemcomprised of the following components: person (host), machine (agency), andenvironment.

The likelihood of an accident occurring is determined by how these componentsinteract. Changes in the patterns of interaction can increase or reduce theprobability of an accident.

For example, an experienced employee who operates a numerically controlledfive-axis machining center in a shop environment may take a two-week vacation.Her temporary replacement may be less experienced. This change in onecomponent of the system (person/host) increases the probability of an accident.Such a simple example is easily understood. However, not all changes in patternsof interaction are this simple. Some are so subtle that their analysis may requirea team of people, each with a different type of expertise.

Systems Theory Model

Machine Person

Environment

Interaction

Collectinformation

Weighrisks

Makedecision

Task to beperformed

Five factors should be considered beforebeginning the process of collectinginformation, weighing risks, and making adecision:

Job requirementsThe workersabilities and limitationsThe gain if the task is successfully

accomplishedThe loss if the task is attempted but failsThe loss if the task is not attempted

Combination Theory

For some accidents, a given model may be very accurate, forothers less so

Often the cause of an accident cannot be adequately explainedby just one model/theory

Actual cause may combine parts of several different models

BEHAVIORAL THEORY OF ACCIDENT CAUSATION

Often referred to as behavior-based safety (BBS) 7 basic principles of BBS

InterventionIdentification of internal factorsMotivation to behave in the desired mannerFocus on the positive consequences of appropriate behaviorApplication of the scientific methodIntegration of informationPlanned interventions

DRUGS AND ACCIDENT CAUSATION

According to surveys by the Department of Health and HumanServices, some 77 percent of drug users are employedmore than9 million workers. An estimated 6.5 percent of full-time and 8.6 ofpart-time workers use illicit drugs. More than a third of all workersbetween the ages of 18 and 25 are binge drinkers. . . . Alcoholismalone causes 500 million lost days annually (125 million days arelost each year due to work-related injuries). . . . Some 20 percent ofworkers report that they have been put in danger or injured, or hadto work harder, redo work or cover for a co-worker, as a result of aco-workers drinking.18

Many companies implement drug-free workplace programs.Drug-free workplace policy, supervisory training, employee

education, employee assistance programs, and alcohol anddrug testing.

DEPRESSION AND ACCIDENTCAUSATION

Depression results in more than 200 million lost workdays andcosts the U.S. economy $43.7 billion annually. Much of that cost ishidden, including $23.8 billion lost to U.S. businesses inabsenteeism and lost productivity. Beyond productivity issues,studies suggest that depressed workers may be more prone toaccidents.

Stephen Heidel, M.D., MBA, an occupational psychiatrist in SanDiego, notes a lack of concentration, fatigue, failing memory andslow reaction time as reasons that workers who are depressed maynot work safely.

Safety and health professionals are not mental health professionals andshould not at-tempt to play that role. However, they should be alert to thewarning signs of clinical depression in employees. These signs are as follows: Persistent dreary moods (sadness, anxiety, nervousness) Signs of too little sleep Sleeping on the job or persistent drowsiness Sudden weight loss or gain General loss of interest, especially in areas of previous interest Restlessness, inability to concentrate, or irritability Chronic physical problems (headaches, digestive disorders, etc.) Forgetfulness or an inability to make simple decisions Persistent feelings of guilt Feelings of low self-worth Focus on death or talk of suicide

MANAGEMENT FAILURES ANDACCIDENT CAUSATION

Poor housekeeping or improper use of tools, equipment, or facilities. Managementeither has not developed the necessary requirements, or has but does not enforcethem. The management failure in this case could be lack of safety procedures (failureto let employees know the expectations), lack of training (failure to give employeesthe knowledge and skills they need to work safely), or failure to properlysupervise (failure to monitor employee actions).

Pressure to meet deadlines. Sometimes management has developed a good safetyand health policy, established good safety and health procedures, built safety andhealth expectations into job descriptions and performance appraisals, and providedthe necessary training only to put all this aside when a rush order comes in. Thismay be the most problematic of the many different types of management failuresthat can occur because it can undermine all of the organizations safety and healthefforts. When management allows safety and health procedures to be ignored or,worse yet, encourages them to be ignored to speed

OBESITY AND ACCIDENT CAUSATION

Obesity has long been associated with such chronic diseases ashigh blood pressure, coronary heart disease, diabetes, and certaintypes of cancer, but these studies now tie it to workplace injuriestoo.

The World Health Organization estimates that there are more than300 million obese people worldwide. In the industrialized nationsof the world nations such as the United Statesthe number ofpeople considered obese is growing rapidly.

These studies used a standard body mass index (BMI) score of 30 orabove to define obesity.