Domino Theory

Definition - What does Domino Theory mean?

The domino theory of accident causation stipulates that injuries occur because of a series of factors, one of which is an accident. In the domino theory, all factors are connected and each of them is dependent on the preceding factor. This means that personal injury (represented as the final domino) occurs only as a result of an accident and the accident itself occurs occurs only as a result of a personal or mechanical hazard.

The theory is structured in ten statements known as the Axioms of Industrial Safety. It identifies a total of five factors in the sequence of events that lead to an accident:

  • Ancestry/social environment
  • Fault of person
  • Unsafe act/mechanical or physical hazard
  • Accident
  • Injury

Safeopedia explains Domino Theory

The domino theory is one of several major theories concerning accident causation. Developed by the safety engineer H. W. Heinrich, it defines an "accident" as one factor in a sequence that may lead to an injury. Heinrich visualizes all relevant factors as a series of dominoes standing on edge; when one falls, the linkage required for a chain reaction is completed.

The systems theory of accident causation expands on the domino theory by describing all situations where an accident might occur as a system with three components: person (host), machine (agency), and environment.


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