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ALARP stands for As Low As Reasonably Practicable, and is a term often used in the milieu of safety-critical and high-integrity systems. The ALARP principle is that the residual risk shall be as low as reasonably practicable.
It means that a risk is low enough that attempting to make it lower would actually be more costly than any cost likely to come from the risk itself. This is called a tolerable risk. The ALARP principle arises from the fact that it would be possible to spend infinite time, effort and money attempting to reduce a risk to zero. It should not be understood as simply a quantitive measure of benifit against detriment. It is more a best common practice of judgement of the balance of risk and societal benefit.
Factors
In this context, risk is the combination of the frequency and the consequence of a specified hazardous event.
The following factors are likely to be considered when deciding whether or not a risk is tolerable.
- Health and safety guidelines
- The specification of the system
- Industry standards
- International standards and laws
- Suggestions from advisory bodies
Another factor that comes into the ALARP principle, is the cost of assessing the improvement gained in an attempted risk reduction. In extremely complex systems, this can be very high, and could be the limiting factor in practicability of risk reduction.
Carrot diagrams
So called carrot diagrams are often used to display risks. They are called carrot diagrams, because they have an elongated triangle in the centre, which looks like a carrot, and indicates the high (reducible) risks at the top and the low (insignificant) risks at the bottom. The region in between is called the ALARP region. An example of a carrot diagram can be found in *.
External links
"ALARP"