Risk and Safety

What are accurate definitions of risk and safety? ISO/IEC Guide 51, which is an international standard, gives the following definitions.

What is risk?
Risk is defined as the “combination of the probability of occurrence of harm and the severity of that harm.” In other words,
Risk = Severity of harm × the probability of the occurrence of harm
What is safety?
Safety is defined as “freedom from which is not tolerable" In other words, tolerable risk is still present even when considered “safe”.

Occurrence of Risk

What does it mean for risk to be present? Examine the following figure.

What does it mean for risk to be present?

In the picture on the left, there is a lion, which is a hazard, but this alone is not enough to cause harm to occur. In the picture on the right, a person is present. This introduces the possibility of harm occurring should the lion attack the person. The picture on the right indicates a situation in which “risk” exists. It is necessary to understand that this situation is distinct from the situation in which a “hazard” exists.

Tolerable Risk

Tolerable Risk

The definition of “safety” is “freedom from risk which is not tolerable” according to ISO/IEC Guide 51. In other words, safety can be achieved by risk reduction to a tolerable level.

  • Strong X Smart X Simple Safety Light Curtain GL-R Series

The page top