Controlling the risks: the hierarchy of control

If more controls are needed, ISO 45001:2018 gives a hierarchy to follow. Elimination is the most preferred option and PPE the least, because effectiveness falls as you move down the list.

1. Elimination. The most important first step. It means avoiding the risk completely, by stopping or not starting the activity that carries it. Removing the risk of a hazardous substance means ending its use altogether. This may involve redesigning the process. Another example is introducing mechanical lifting devices to remove a manual handling hazard.
2. Substitution. If elimination is not possible, find a less risky method. This can mean tackling the risk at source by adopting technical progress, for example replacing solvent-based paint with water-based paint, or reducing the energy in the system by lowering the force, current, pressure or temperature.
3. Engineering controls. These are collective protective measures, preferred to individual ones. The process is designed so that the hazard is contained or separated from people. Examples include gas detection and shutdown systems, ventilation to control exposure to hazardous substances, isolation, machine guarding, mechanical handling and guard rails against falls from height.
4. Administrative controls. If risk remains, administrative controls address it. These include information, instruction, training, restricted access, safety signs, area marking, toolbox talks, permit to work and supervision.
5. PPE. If risk still remains, personal protective equipment handles what is left. It may include protection for the eyes, face, hands and forearms, as required.

Administrative controls and PPE need continuing effort from workers and supervisors. They are useful while other controls are being put in place, and they are often applied to existing processes where hazards are not well controlled.

Principles to consider when controlling risk

ILO-OSH 2001 says hazards and risks to workers should be identified and assessed on an ongoing basis, and that preventive and protective measures should be applied in this order of priority:

1. Eliminate the hazard or risk.
2. Control the hazard or risk at source, using engineering controls or organisational measures.
3. Minimise the hazard or risk by designing safe work systems, including administrative control measures.
4. Where residual hazards or risks cannot be controlled by collective measures, the employer should provide suitable personal protective equipment, including clothing, at no cost, and should take measures to ensure its use and maintenance.

The work of choosing controls is not finished yet. You must also consider:

• the need for a combination of controls, for example engineering and administrative controls together
• good practice for the particular hazard, and adapting work to the individual, taking account of mental and physical capabilities
• technical progress that can improve controls
• measures that protect everyone, such as engineering controls that protect all those near a hazard instead of individual PPE
• human behaviour, and whether a control will be accepted and can be carried out effectively
• the basic types of human failure, such as failure in a frequently repeated action, lapses of memory or attention, lack of understanding or errors of judgement, and breaches of rules or procedures, and ways to prevent them
• the need for planned maintenance, for example of machinery safeguards
• the possible need for emergency or contingency arrangements if controls fail
• the unfamiliarity with the workplace and its controls of people who are not direct employees, such as visitors and contractors

Priorities and timescales

There is a simple link between the level of risk and the priority of a hazard: the higher the risk, the higher the priority. A high risk needs a short timescale for corrective action, and a low risk allows a longer one. Two problems affect this simple link.

• A low risk may be a low priority, yet it may also have a very simple, cheap remedy. A court might not accept a long timescale for a cheap, easy fix. If it can be done at once, it should be.
• A medium risk may deserve medium priority, but that does not mean a court would accept waiting. The risk to workers should always be acceptable, not just acceptable after 24 hours of working.

Step 4: record the findings

Record all significant findings: the hazards, how people might be harmed, and what the organisation already has in place to control the risks. The record should be simple and focused on controls. A simple way is to use the HSE risk assessment template (hse.gov.uk/risk). The template below is the one used in the practical unit.

The template also carries the organisation name, the date of assessment and the scope of the assessment.

The amount of documentation depends on the level of risk, legal requirements, and the requirements of any management system in place.

Summary notes for Element 3 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.