What Does
Domino Theory Mean?
The domino theory of accident causation stipulates that workplace accidents occur because of a series of factors, only one of which is the accident itself.
According to the domino theory, all these factors are connected and all must be in place for the accident to occur.
Safeopedia Explains Domino Theory
The domino theory was coined by Herbert W. Heinrich, famous for the Safety Pyramid and other seminal concepts in occupational safety. It was the first of his “10 axioms of industrial safety,” which were published in his 1931 book Industrial Accident Prevention: A Scientific Approach.
The Five Dominos
Heinrich identified five different factors that make up the sequence of events that lead to a worker getting injured on the job. These are:
- The social environment and “ancestry” (meaning personal beliefs, character traits, and skills)
- Personal fault (inattention or carelessness)
- An unsafe act or a mechanical or physical hazard (a failure in the equipment, workplace design, or working procedure)
- The resulting accident
- The injury caused by the accident
Significance of the Domino Theory
The point of the domino theory is to demonstrate that a single cause is never sufficient to explain why an incident or injury took place in an occupational setting.
It also represented an important evolution in our understanding of accident causation. Heinrich’s book was published at a time when the blame for accidents was typically pinned on a worker being accident prone or simply careless.
These explanations are represented by the first two dominos (ancestry and personal fault). The subsequent dominos, however, illustrate the fact that neither being accident prone or careless are sufficient conditions for an accident or injury to take place. With safe working procedures or adequate hazard controls (in essence, removing the third domino), accidents could be prevented, no matter the worker’s character.
The Domino Theory Today
While a compelling and historically significant concept, the domino theory doesn’t hold much purchase in modern occupational health and safety.
The basic concept that an accident is the result of several causal factors is still widely accepted. It is, however, seen more as a complex web of factors that interact with one another, rather than an ordered sequence of causes.
The domino theory also still places much of the blame squarely on the behavior of workers. Insofar as it takes the working environment and other conditions into consideration, it is less focused on individual actions than the concept of workers being accident prone. Nevertheless, it is at odds with the belief, widely held by safety professionals, that placing fault on individual action is counterproductive to understanding and preventing incidents.
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