What does ALARP mean?

The information below is extracted and summarised from an HSE online document entitled “ALARP at a glance”.

“ALARP” is short for “as low as reasonably practicable”. “SFAIRP” is short for “so far as is reasonably practicable”. The two terms mean essentially the same thing and at their core is the concept of “reasonably practicable”; this involves weighing a risk against the trouble, time and money needed to control it. Thus, ALARP describes the level to which we expect to see workplace risks controlled. Using “reasonably practicable” allows us to set goals for duty-holders, rather than being prescriptive.

The definition set out by the Court of Appeal (in its judgment in Edwards v. National Coal Board, [1949] 1 All ER 743) is: “‘Reasonably practicable’ is a narrower term than ‘physically possible’ … a computation must be made by the owner in which the quantum of risk is placed on one scale and the sacrifice involved in the measures necessary for averting the risk (whether in money, time or trouble) is placed in the other, and that, if it be shown that there is a gross disproportion between them – the risk being insignificant in relation to the sacrifice – the defendants discharge the onus on them.”

In essence, making sure a risk has been reduced ALARP is about weighing the risk against the sacrifice needed to further reduce it. The decision is weighted in favour of health and safety because the presumption is that the duty-holder should implement the risk reduction measure. To avoid having to make this sacrifice, the duty-holder must be able to show that it would be grossly disproportionate to the benefits of risk reduction that would be achieved. Thus, the process is not one of balancing the costs and benefits of measures but, rather, of adopting measures except where they are ruled out because they involve grossly disproportionate sacrifices.

Definition of a hazard

A hazard is something (e.g. an object, a property of a substance, a phenomenon or an activity) that can cause adverse effects. For example: Water on a staircase is a hazard, because you could slip on it, fall and hurt yourself. Loud noise is a hazard because it can cause hearing loss. Breathing in asbestos dust is a hazard because it can cause cancer.

Definition of a risk

A risk is the likelihood that a hazard will actually cause its adverse effects, together with a measure of the effect. It is a two- part concept and you have to have both parts to make sense of it. Likelihoods can be expressed as probabilities (e.g. “one in a thousand”), frequencies (e.g. “1000 cases per year”) or in a qualitative way (e.g. “negligible”, “significant”, etc.). The effect can be described in many different ways. For example: The annual risk of a worker in Great Britain experiencing a fatal accident [effect] at work [hazard] is less than one in 100,000 [likelihood]; About 1500 workers each year [likelihood] in Great Britain suffer a non-fatal major injury [effect] from contact with moving machinery [hazard]; or The lifetime risk of an employee developing asthma [effect] from exposure to substance X [hazard] is significant [likelihood].

In most situations, deciding whether the risks are ALARP involves a comparison betweenthe control measures a dutyholder has in place or is proposing and the measures we  would normally expect to see in such circumstances i.e. relevant good practice.

“Good practice” is defined in the general ALARP guidance as “those standards for controlling risk that HSE has judged and recognised as satisfying the law, when applied to a particular relevant case, in an appropriate manner.”

Once what is good practice has been determined, much of the discussion with duty-holders about whether a risk is or will be ALARP is likely to be concerned with the relevance of the good practice, and how appropriately it has been (or will be) implemented.. Where there is relevant, recognised good practice, we expect duty-holders to follow it. If they want to do something different, they must be able to demonstrate to our satisfaction that the measures they propose to use are at least as effective in controlling the risk.

Some fallacies about ALARP

Some myths or fallacies about what ALARP means have grown up over the years. Here we explain what some of these myths are and, why they are wrong.

Fallacy 1 – Ensuring that risks are reduced ALARP means that we have to raise standards continually It is part of HSC/E’s philosophy that we seek continual improvements in health and safety standards. That philosophy is widely shared in HSE and because of it, Britain has one of the best records for occupational health and safety in the world. HSE is rightly respected for this. However, we need to make sure that we encourage improvements in a responsible way. Deciding whether something is safe enough (i.e. the risk is reduced ALARP) is a separate exercise from seeking a continual improvement in standards. Of course, as technology develops, new and better methods of risk control become available. Duty-holders should review what is available from time to time and consider whether they need to implement new controls. But that doesn’t mean that the best risk controls available are necessarily reasonably practicable. It is only if the cost of implementing these new methods of control is not grossly disproportionate to the reduction in risk they achieve that their implementation is reasonably practicable. For that reason, we accept that it may not be reasonably practicable to upgrade older plant and equipment to modern standards. However, there may still be other measures that are required to reduce the risk ALARP: for example, partial upgrades or alternative measures. Our decision about what is ALARP will also be affected by changes in knowledge about the size or nature of the risk presented by a hazard. If there is sound evidence to show that a hazard presents significantly greater risks than previously thought, then of course we should press for stronger controls to tackle the new situation. However, if the evidence shows the hazard presents significantly lesser risks than previously thought, then we should accept a relaxation in control provided the new arrangements ensure the risks are ALARP.

Fallacy 2 – If a few employers have adopted a high standard of risk control, that standard is ALARP Some organisations implement standards of risk control that are more stringent than good practice. They may do this for a number of reasons, such as meeting corporate social responsibility goals, or because they strive to be the best at all they do, or because they have reached an agreement with their staff to provide additional controls. It does not follow that these risk control standards are reasonably practicable, just because a few organisations have adopted them. Until such practices are evaluated and recognised by HSE as representing good practice, you should not seek to enforce them (whether at a policy level or an operational one). It is also acceptable for a duty holder to choose to relax from a self-imposed higher standard to one which is accepted as ALARP (e.g. just meeting the requirements of a relevant ACOP).

Fallacy 3 – Ensuring that risks are reduced ALARP means that we can insist on all possible risk controls ALARP does not mean that every measure that could possibly be taken (however theoretical) to reduce risk must be taken. Sometimes, there is more than one way of controlling a risk. These controls can be thought of as barriers that prevent the risk being realised and there is a temptation to require more and more of these protective barriers, to reduce the risk as low as possible. (The so-called “belt and braces” approach.) You must remember that ALARP means that a barrier can be required only if its introduction does not involve grossly disproportionate cost.

Fallacy 4 – Ensuring that risks are reduced ALARP means that there will be no accidents or ill- health ALARP does not represent zero risk. We have to expect the risk arising from a hazard to be realised sometimes, and so for harm to occur, even though the risk is ALARP. This is an uncomfortable thought for many people, but it is inescapable. Of course we should strive to make sure that duty-holders reduce and maintain the risks ALARP, and we should never be complacent but, nevertheless, we have to accept that risk from an activity can never be entirely eliminated unless the activity is stopped.

Useful links:


Collaton Consultancy Limited act as Expert Witness, trainers, consultants in the area of Legionella Risk Management so if we can help you please contact us via general@collatonconsultancy.com or phone on +44 (0)7958 124563.

Check out our websites:




Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.