ALARP
Encyclopedia
ALARP stands for "as low as reasonably practicable", and is a term often used in the milieu of safety-critical and safety-involved
systems. The ALARP principle is that the residual risk shall be as low as reasonably practicable. It has particular connotations as a route to reduce risks SFAIRP (so far as is reasonably practicable) in UK Health and Safety law
.
For a risk
to be ALARP it must be possible to demonstrate that the cost involved in reducing the risk further would be grossly disproportionate to the benefit gained. The ALARP principle arises from the fact that infinite time, effort and money could be spent on the attempt of reducing a risk to zero. It should not be understood as simply a quantitive measure of benefit against detriment. It is more a best common practice of judgement of the balance of risk and societal benefit.
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.
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.
Determining that a risk has been reduced to ALARP involves an assessment of the risk to be avoided, of the sacrifice (in money, time and trouble) involved in taking measures to avoid that risk, and a comparison of the two. This is a cost-benefit analysis.
The key question in determining whether a risk is ALARP is the definition of reasonably practicable. This term has been enshrined in the UK case law
since the case of Edwards v. National Coal Board
in 1949. The ruling was that the risk must be insignificant in relation to the sacrifice (in terms of money, time or trouble) required to avert it: risks must be averted unless there is a gross disproportion between the costs and benefits of doing so.
Including gross disproportion means that an ALARP judgement in the UK is not a simple cost benefit analysis, but is weighted to favour carrying out the safety improvement. However, there is no broad consensus on the precise factor that would be appropriate.
The term ALARA, or "as low as reasonably achievable" is used interchangeably in the United States of America, almost exclusively in the field of Radiation Protection.
Where the ALARP principle is used, it may not have the same implications as in the UK, as "reasonably practicable" may be interpreted according to the local culture, without introducing the concept of gross disproportionality.
resulted in the SFAIRP principle being upheld on 18 January 2007.
The European Commission
had claimed that the SFAIRP wording in the Health & Safety at Work Act did not fully implement the requirements of the Framework Directive
. The Directive gives employers an absolute duty "to ensure the safety and health of workers in every aspect related to the work", whereas the Act qualifies the duty "So Far As is Reasonably Practicable". The court dismissed the action and ordered the Commission to pay the UK's costs.
Had the case been upheld, it would have called into question the proportionate approach to safety risk management embodied in the ALARP principle.
So called carrot
diagram
s 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 (normally unacceptable) risks at the top and the low (broadly tolerable) risks at the bottom. The region in between is sometimes called the ALARP region; however this is misleading because the ALARP principle applies to all regions. A better name is the 'Tolerable Region', because risks in this region can sometimes be tolerated, if they cannot practically be reduced, in return for the benefits provided by the system or installation that causes the risks.
Safety-involved
Safety-involved systems are related to safety-critical systems, but are those that do not have full responsibility for controlling hazards such as loss of life, severe injury or severe environmental damage. The malfunction of a safety-involved system would only be that hazardous in conjunction...
systems. The ALARP principle is that the residual risk shall be as low as reasonably practicable. It has particular connotations as a route to reduce risks SFAIRP (so far as is reasonably practicable) in UK Health and Safety law
Health and safety law
Health and safety law is a body of law that protects the health, safety and welfare of the general public and certain defined sectors of the population such as employees...
.
For a risk
Risk
Risk is the potential that a chosen action or activity will lead to a loss . The notion implies that a choice having an influence on the outcome exists . Potential losses themselves may also be called "risks"...
to be ALARP it must be possible to demonstrate that the cost involved in reducing the risk further would be grossly disproportionate to the benefit gained. The ALARP principle arises from the fact that infinite time, effort and money could be spent on the attempt of reducing a risk to zero. It should not be understood as simply a quantitive measure of benefit against detriment. It is more a best common practice of judgement of the balance of risk and societal benefit.
Factors
In this context, riskRisk
Risk is the potential that a chosen action or activity will lead to a loss . The notion implies that a choice having an influence on the outcome exists . Potential losses themselves may also be called "risks"...
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
- International standards and laws
- Suggestions from advisory bodies
- Comparison with similar hazardous events in other industries
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.
Determining that a risk has been reduced to ALARP involves an assessment of the risk to be avoided, of the sacrifice (in money, time and trouble) involved in taking measures to avoid that risk, and a comparison of the two. This is a cost-benefit analysis.
Origin in UK law
The term ALARP arises from UK legislation, particularly the Health and Safety at Work etc. Act 1974, which requires "Provision and maintenance of plant and systems of work that are, so far as is reasonably practicable, safe and without risks to health". The phrase So Far As is Reasonably Practicable (SFARP) in this and similar clauses is interpreted as leading to a requirement that risks must be reduced to a level that is As Low As is Reasonably Practicable (ALARP).The key question in determining whether a risk is ALARP is the definition of reasonably practicable. This term has been enshrined in the UK case law
Case law
In law, case law is the set of reported judicial decisions of selected appellate courts and other courts of first instance which make new interpretations of the law and, therefore, can be cited as precedents in a process known as stare decisis...
since the case of Edwards v. National Coal Board
Edwards v. National Coal Board
Edwards v. National Coal Board was an important case in English case law. The 1949 case revolved around whether it was "reasonably practicable" to prevent even the smallest possibility of a rock fall in a coal mine.-Underlying facts:...
in 1949. The ruling was that the risk must be insignificant in relation to the sacrifice (in terms of money, time or trouble) required to avert it: risks must be averted unless there is a gross disproportion between the costs and benefits of doing so.
Including gross disproportion means that an ALARP judgement in the UK is not a simple cost benefit analysis, but is weighted to favour carrying out the safety improvement. However, there is no broad consensus on the precise factor that would be appropriate.
Use outside the UK
Outside the UK the ALARP principle is often not used; instead standards and 'good engineering practice' are adhered to, and legislation tends to require absolute levels of safety.The term ALARA, or "as low as reasonably achievable" is used interchangeably in the United States of America, almost exclusively in the field of Radiation Protection.
Where the ALARP principle is used, it may not have the same implications as in the UK, as "reasonably practicable" may be interpreted according to the local culture, without introducing the concept of gross disproportionality.
Legal challenge
A 2-year legal battle in the European Court of JusticeEuropean Court of Justice
The Court can sit in plenary session, as a Grand Chamber of 13 judges, or in chambers of three or five judges. Plenary sitting are now very rare, and the court mostly sits in chambers of three or five judges...
resulted in the SFAIRP principle being upheld on 18 January 2007.
The European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
had claimed that the SFAIRP wording in the Health & Safety at Work Act did not fully implement the requirements of the Framework Directive
Directive 89/391/EEC
The EU Workplace Health and Safety Directive is a European Union directive that sets out general principles for protection of workers' Occupational safety and health...
. The Directive gives employers an absolute duty "to ensure the safety and health of workers in every aspect related to the work", whereas the Act qualifies the duty "So Far As is Reasonably Practicable". The court dismissed the action and ordered the Commission to pay the UK's costs.
Had the case been upheld, it would have called into question the proportionate approach to safety risk management embodied in the ALARP principle.
Carrot diagrams
Carrot
The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...
diagram
Diagram
A diagram is a two-dimensional geometric symbolic representation of information according to some visualization technique. Sometimes, the technique uses a three-dimensional visualization which is then projected onto the two-dimensional surface...
s 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 (normally unacceptable) risks at the top and the low (broadly tolerable) risks at the bottom. The region in between is sometimes called the ALARP region; however this is misleading because the ALARP principle applies to all regions. A better name is the 'Tolerable Region', because risks in this region can sometimes be tolerated, if they cannot practically be reduced, in return for the benefits provided by the system or installation that causes the risks.