Historical Perspective and Overview

Accident Causation

Why do accidents happen? This question has concerned safety &

health decision makers for decades. Theories of accident causation have

evolved that attempt to explain why accidents occur.

Models based on theories are used to predict & prevent accidents.

Domino Theory

An early pioneer of accident prevention and industrial safety was Herbert W. Heinrich.

From research done in the late 1920’s, he concluded that 88% of industrial accidents are caused by unsafe acts committed by fellow workers.

10% are caused by unsafe conditions.

Domino Theory

2% of industrial accidents are unavoidable.

This study led to his Axioms of Industrial Safety, which was contained in 10 statements.

The belief was that any accident prevention program that uses all 10 axioms would be the most effective.

Domino Theory

Literally, the theory works like a row of dominos, were the first one tips over the next and so on.

He believed that there were five factors in the sequence of events leading up to and accident.

Domino Theory

Ancestry and social environment, fault of the person, unsafe act/mechanical or physical hazard, accident, and injury.

Two central points: injuries are caused by the action of the preceding factors; and removal of the central factor negates the action of the preceding factors.

Human Factors Theory Attributes accidents to a chain of events

ultimately caused by human error. It consists of three broad factors that

lead to human error: overload, inappropriate response, and inappropriate activities.

Overload

An imbalance between a person’s capacity at any given time and the load that person is carrying in a given state.

Person’s capacity - natural ability, training, state of mind, fatigue, stress, and physical condition.

Overload

Load - tasks responsible for, environmental (noise, distraction), internal (personal problems, emotional stress, and worry), and situational factors (level of risk, unclear instruction).

Given state - product of his or her motivational and arousal levels.

Inappropriate Response Detecting a hazard but not correcting it. Removing safeguards from machines

and equipment. Ignoring safety procedures. Workstation incompatibility.

Inappropriate Activities A person who undertakes a task that he

or she doesn’t know how to do. A person who misjudges the degree of

risk involved in a given task and proceeds based on that misjudgment.

Accident/Incident Theory Extension of the human factor theory. Introduced new elements: ergonomic

traps, the decision to err, and systems failure.

The decision to err may be conscious or unconscious.

Deadlines, peer pressure, and budget factors can lead to unsafe behavior.

Accident/Incident Theory Another factor that can influence such a

decision is the “It won’t happen to me” syndrome.

Systems failure - shows the potential for a causal relationship between management decisions or behavior and safety.

Establishes management’s role in accident prevention.

Epidemiological Theory Study of causal relationships between

environmental factors and disease. Holds that the models used for studying

these relationships can also be used to study causal relationships between environmental factors and accidents.

Key components are predispositional and situational characteristics.

Epidemiological Theory If an employee who is particularly

susceptible to peer pressure (predispositional characteristic) is pressured by his coworkers (situational characteristic) to speed up his operation, the result will be an increased probability of an accident.

Systems Theory

A group of regularly interacting and interrelated components that together form a unified whole.

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

Systems Theory

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

Changes in the patterns of interaction can increase or reduce the probability of an accident.

Additional parts are information, decisions, risks, and the task to be performed.

Combination Theory

Often the cause of an accident cannot be adequately explained by just one model or theory.

The actual cause may combine parts of several different models.

Should avoid the tendency to try to apply one model to all accidents.

Behavioral Theory

Seven principals of behavior-based safety: intervention; identification of internal factors; motivation to behave in the desired manner;focus on the positive consequences of appropriate behavior; application of the scientific method, integration of information; and planned interventions.

Drugs and Accident Causation Drugs and alcohol are the root or

contributing cause of many accidents. Approximately 77% of drug users are

employed. More than a third of all workers between

the ages of 18 and 25 are binge drinkers.

Drugs and Accident Causation Alcoholism alone causes 500 million lost

days annually. Some 20% of workers report that they

have been put in danger or injured, had to work harder, redo work or cover for a co-worker, as a result of a co-worker’s drinking.

Depression and Accident Causation Can be an invisible problem in the

workplace. One in 20 people suffer from clinical

depression, which is the root cause of more than 200 million lost work days.

Causes are biological, cognitive, genetic, and concurring illnesses.

Management Failures

Management failures are another leading cause of accidents in the workplace.

If management is serious about workplace safety and health, it must establish expectations, provide training, evaluate employee performance with safety in mind, and reinforce safe and healthy behavior.

Role of the Supervisor

Supervisors are of key importance in ensuring the success of safety in the workplace.

Responsibilities include: orientation, safety training, monitoring performance, enforcing safety rules, accident investigations & reports, staying up to date, and setting a positive example.

Obesity and Accident Causation Extremely obese people are more likely than

normal-weight people to injure themselves. 26% of obese males and 22% of obese

females reported personal injuries (compared to 17% and 12%).

Most common causes of injuries to obese people were overexertion (35.2%) and falls (29.9%).