ALARP stands for “As Low As Reasonably Practicable.” It is a fundamental principle in occupational health and safety (OHS) and risk management. It states that risks should be reduced to the lowest possible level, i.e., reasonably practicable, considering the balance between risk reduction and the associated cost, time, effort, or inconvenience required to achieve it. The key element is “reasonably practicable,” meaning that further risk reduction measures should not be grossly disproportionate to the additional risk reduction achieved.
Explanation of the Term “As Low As Reasonably Practicable”
The ALARP principle recognises that while it’s often impossible to eliminate all risks, especially in complex or inherently hazardous industries, risks must be controlled to the lowest possible level without incurring disproportionate effort, time, money, or inconvenience. It’s a continuous process of identifying hazards, assessing risks, implementing control measures, and then reviewing if further controls can be applied without the cost outweighing the benefit of the additional risk reduction.
The ALARP principle means that employers must take all reasonable steps to minimise workplace hazards unless the cost (in terms of money, time, effort or inconvenience) of further risk reduction would be grossly disproportionate to the safety benefit gained. This means that a substantial investment of time, money, and effort is expected to reduce very high risks. However, an equally significant investment would be considered disproportionate for very low risks. The presumption always favours health and safety; the burden of proof lies with the duty holder to demonstrate that all reasonably practicable steps have been taken.
This does not mean eliminating all risk, which is often impractical. Instead, it requires demonstrating that all reasonable steps have been taken to reduce the risk to the lowest possible level without incurring disproportionate costs.
ALARP is often visualised using a risk matrix, where risks fall into three zones:
- Unacceptable Risk – Must be reduced regardless of cost.
- Tolerable Risk (ALARP Zone) – Acceptable only if further reduction is not reasonably practicable.
- Broadly Acceptable Risk – Minimal risk, requiring no further action.
Example:
Scenario: Noisy machinery in a manufacturing plant exposes workers to 92 dB, which exceeds safe limits (typically 85 dB over 8 hours).
Possible Controls:
- Elimination/Substitution – Replace machinery with quieter models (may be costly).
- Engineering Controls – Install soundproof barriers or vibration dampeners.
- Administrative Controls – Rotate workers to limit exposure time.
- PPE – Provide hearing protection (least effective but cheapest).
ALARP Decision:
- If installing soundproofing reduces noise to 82 dB at a reasonable cost, this would be reasonably practicable.
- If replacing all machinery costs millions but only marginally reduces risk, it may be grossly disproportionate, making PPE + rotation the ALARP solution.
By applying ALARP, the employer ensures risks are minimised as far as possible without imposing unreasonable burdens, balancing safety and practicality.