SFAIRP v ALARP. It’s a well-worn argument and the subject of many heated internet debates. The question often asked is, is there actually any real difference between the two?
After 15 years in safety engineering, I’ve come to realise that while the principles of reducing risk SFAIRP (So Far As Is Reasonably Practicable) or ALARP (As Low As Reasonably Practicable) may be shared, the practice can be surprisingly different – particularly when you compare them across different countries and different industries.
Having worked in the Australian rail industry and global oil and gas industry when I lived in the UK, I’ve had a good deal of exposure to the way the principles of SFAIRP and ALARP are embedded in those industries and cultures, as well as the differences and similarities between them.
At their core, both SFAIRP and ALARP express a balance between risk reduction and the cost, time, or effort needed to achieve it. They are often treated as interchangeable, and indeed legislation in both Australia and the UK, namely the Work Health and Safety Act 2011 and the Health and Safety at Work Act 1974, state that if hazards cannot be eliminated, then the risk needs to be reduced so far as is reasonably practicable.
However, something that I’ve noticed over my career is the way in which SFAIRP and ALARP are interpreted in practice can differ between sectors and geographies.
How are they the same?
In the Australian rail industry, the philosophy of reducing risks SFAIRP is embodied in legislation, notably under Rail Safety National Law. The focus is on demonstrating that all hazards have been identified and that all reasonable controls have been applied to prevent and mitigate those hazards from resulting in harm to people.
This often translates into structured risk assessments, robust engineering change processes, and documented evidence that no feasible hazards or control measures have been left unconsidered.
From working with rail transport operators and rail infrastructure managers, I have seen how they are expected not only to analyse the likelihood and consequence of a hazard, but also to justify decisions through comparative assessments, such as why a control wasn’t implemented, or why a certain mitigation is sufficient.
There’s an emphasis on traceability and justification over numerical thresholds alone.
From my experience in the oil and gas sector, the concept of ALARP has been deeply integrated into many safety regimes, developed from regulations and guidance documents published by the UK Health and Safety Executive as the Regulator.
However, the legislation which underpins this guidance is the Health and Safety at Work Act 1974, which only references So Far As Is Reasonably Practicable and not As Low As Reasonably Practicable. Standards commonly used in the rail industry, such as EN 50126-2, describes ALARP as sometimes being abbreviated as SFAIRP.
Therefore, surely it is reasonable to assume that SFAIRP and ALARP are the same when they appear to be interchangeable?
How are they different?
Working on global projects from the UK, the ALARP principle extends beyond the North Sea. Many organisations embed ALARP into their corporate risk processes across regions, from Africa to Asia, carrying with them a culture of risk tolerability matrices, ALARP demonstration checklists, and cost-benefit analysis as standard practice when determining risk reduction strategies.
The oil and gas industry often places greater reliance on quantified risk assessment techniques. While both ALARP and SFAIRP arguments must justify decisions, assessing hazards in oil and gas often focuses on modelling and numerical thresholds as part of the ALARP justification.
I’ve also observed differences in how low-risk hazards are managed. Low-risk hazards are sometimes considered tolerable or acceptable without further consideration of controls, often based on where the risk lies on a matrix, which is a subjective assessment of likelihood and consequence.
From a SFAIRP perspective, risk reduction should continue until it becomes grossly disproportionate, whereas under ALARP it is sometimes seen that no additional measures are applied once hazards have been subjectively classified as low risk.
What it means in practice is that much more time and effort is afforded to those hazards which have a potentially catastrophic or a more likely outcome.
So, is there really a difference between SFAIRP and ALARP?
Technically, no, but from my observations, yes. The principles align but the interpretation and application can vary by industry and geography.
Does it matter?
What matters most is how we tell the story, not just how a risk scores on a matrix, but how we’ve shown due diligence in controlling it. Whether you’re using SFAIRP or ALARP, the goal is the same, to do what’s reasonably practicable to keep people safe.
As safety engineers, our job isn’t just to apply the process, but to communicate the rationale clearly and transparently. That’s a universal language, no matter where in the world you’re working.
What experiences have you had in applying SFAIRP or ALARP across sectors? Are you a business operating in multiple countries or industries, trying to navigate different frameworks? It would be great to hear your thoughts and experiences.
Staff Profile: Campbell Sims | Principal Systems & Safety Assurance Consultant
Related Content: How to Argue Risk is Reduced SFAIRP
