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The Assessment and evaluation of risk


A key element to the management of health and safety is the identification of associated hazards (things that may cause harm) and the likelihood that potential harm will be realised. The risk assessment process allows organisations to look at their risk and control it to a level that would be deemed acceptable.

Next, we will look at risk management and the risk assessment process.


Hazard: ‘something with the potential to cause harm (this can include articles, substances, plant or machines, methods of work, the working environment and other aspects of work organisation)’

Risk: ‘the likelihood of potential harm from that hazard being realised’

Risk assessment: ‘identifying preventive and protective measures by evaluating the risk(s) arising from a hazard(s), taking into account the adequacy of any existing controls, and deciding whether or not the risk(s) is acceptable’


Risk assessments can be carried out in many ways, although mostly the basic principles remain the same. The following is the UK HSE’s five step approach:

  1. Identify the hazards
  2. Identify who can be harmed and how
  3. Evaluate the risk associated with the hazards and decide whether existing precautions are adequate or more control is required
  4. Record the significant findings
  5. Review the assessment


There are several different risk assessments available to use. In the UK and some other countries, it is a legal requirement to carry out an assessment of the risks.

Generic Risk Assessments

Generic risk assessments written assessments, and provide the framework to describe how all risk assessments are carried out in practice. Many assessments are dynamic, forever changing to deal with the changing nature of the work.

Specific Risk Assessments

Specific risk assessments can be used in “specific” scenarios to assess “specific” areas. For example, a specific risk assessment could be conducted for:

  • Working at height
  • A project site/activity
  • Manual handling
  • fire

In some circumstances, specific risk assessments relate to legal requirements or duty. In the UK for example entities must carry out specific risk assessments for the likes of fire, noise, asbestos etc. The specific legal requirements must be fed into the risk assessment where this is the case.

Dynamic Risk Assessments

A dynamic assessment is a continuous assessment of risk in a rapidly changing environment to implement control measures necessary to ensure an acceptable level of safety is maintained. They are not written down, but take place within a framework that enables competent persons to respond to changing circumstances. Emergency services must make dynamic risk assessments when dealing with call-outs for example, but receive training on the use of various response techniques.

A dynamic Risk Assessment Method sets out five stages:

  • Evaluate the situation: consider issues such as what operational intelligence is available, what tasks need to be carried out, what are the hazards, where are the risks, who is likely to be affected, what resources are available?
  • Select systems of work: consider the possible systems of work and choose the most appropriate.
  • Assess the chosen systems of work: are the risks proportional to the benefits?
  • responsibilities have been clearly allocated; and safety measures and procedures are understood. If no, continue as below.
  • Introduce additional controls: reduce residual risks to an acceptable level;
  • Reassess systems of work and additional control measures:

Dynamic assessments largely depend upon the knowledge and competence of the person carrying it out. For example, a postman on his own would assess the risk each time he enters a garden or house driveway to post his mail. He may face different situations each time and as such is constantly aware of his surroundings assessing what he needs to do to be safe.

Limitations of the risk assessment processes

Regulators must also acknowledge that there is an ethical dimension to the public’s attitude to acceptance of risk. There are some people who judge that certain hazards should not be entertained at all, no matter how low the risks, eg. in relation to nuclear power. Others feel that the use of risk assessment is morally wrong because, however small the risks may be, it legitimises the concept that it is acceptable for some people to be exposed to man-made risks, for the environment to be polluted or for experiments to be done on animals, so that others may benefit.

From a different perspective, there is a strong belief from some parts of industry and elsewhere that risk assessment may overestimate risks and therefore cause undue alarm and despondency among the public, particularly those risk assessments that represent the worst-case scenarios. On the other hand, many pressure groups believe that risk assessment may often inherently underestimate the true magnitude of the problem, by ignoring, for example, salient factors such as synergies among exposures and vast variations in susceptibility among humans.

Perhaps all this is but recognition that assessing risks is full of uncertainties; that the science underlying most risk assessment assumptions is often inconclusive or untestable. In short risk assessment in its present form can only be used to inform a decision. It should not be used blindly to dictate it.

Temporary and non-routine situations

A suitable and sufficient risk assessment should cover the hazards and significant risks of all work activities, including routine and non-routine, temporary work, one-off as well as regular activities. Non-routine and temporary works are jobs and tasks that are performed irregularly or being performed for the first time. Since these tasks and jobs are not performed regularly, it can be difficult to understand all of the hazards associated with the job. The non-routine and temporary works are to be strictly controlled via permit to work practice and risk assessments

Consideration of long-term hazards to health

When undertaking risk assessment, the hazards to health may not be immediately recognisable. We should consider the potential long-term damage or health effects that the hazard may have. For example: Asbestos has a long gestation period meaning that it can take many years for the symptoms and effects to show.

Qualitative, semi-quantitative and quantitative assessments

Risk assessments can be simple or complex depending on the activities or processes being assessed. Generally, there are three types of risk assessment;

  • Qualitative
  • Semi-Quantitative
  • Quantitative

Qualitative Risk Assessment

Where the hazards presented by the undertaking are few or simple, for example in many small businesses, it is appropriate to just carry out a simple qualitative risk assessment. A qualitative risk assessment should be a systematic examination of what in the workplace could cause harm to people, so that decisions can be made as to whether existing precautions or control measures are adequate or whether more needs to be done to prevent harm.

In a qualitative assessment, it is appropriate to complete just the following steps:

  • Identify the hazards;
  • Identify the possible consequences (Decide who might be harmed and how);
  • Evaluate risk (and decide whether the existing precautions are adequate or whether more should be done)
  • Record the findings.

Semi-Quantitative Risk Assessment

In carrying out semi-quantitative risk assessments, simple qualitative techniques, supplemented by for example measurements to identify the presence of hazards from chemicals or machinery, or the use of simple modelling techniques may be appropriate. Simple modelling techniques may be used to derive order of magnitude estimates of the severity of the consequences and likelihood of realisation of hazards. These estimates can be combined to obtain estimates of the order of magnitude of the risk.

Quantitative Risk Assessment

Quantitative risk assessment is the most commonly used method in process industries. It allows for quantification of risk for major hazards. It is used primarily in the oil & gas and nuclear sectors.

In carrying out quantitative risk assessments, special quantitative tools and techniques will be used for hazard identification, and to estimate the severity of the consequences and the likelihood of realisation of the hazards. Where such methods and techniques are used, it is important that they are carried out by suitably qualified and experienced assessors. The results of the QRA will be numerical estimates of the risk, which can be compared to numerical risk criteria at the risk evaluation stage.

The use of risk assessment in the development of safe systems of work and safe operating procedures

A risk assessment is the first assessment that allows the organisation to build a picture of the hazards and risks. Once completed, the risk assessment provides controls that are required in order to provide a safe activity. As such, the risk assessment can be used to draw information when developing a safe system of work or indeed a safe operating procedure.

Acceptability/tolerability of risk

This is the risk that remains once controls have been decided. An example could be working at height whereby a slip results in a fall, insufficient guarding, by placing the guard rail this could prevent the fall but the slip might remain. It is the same with other situations whereby all reasonable measures are taken to remove the risk but a small residual risk remains.

Once residual risk has been identified and control measures applied, it remains to be seen if the residual risk will be of an acceptable level. One can conclude that sufficiency of knowledge is deemed acceptable to ascertain the risk parameters, however, legislation places a general duty to reduce the level of risk so far as reasonably practicable. Therefore ‘practicable’ means employers must use any new technologies to reduce the likelihood of harm.

The UK’s HSE produced a book entitled “Reducing risks, protecting people”. The book and discussion lays out the principles of acceptability and tolerability giving a balanced view of what should be considered and taken into account.

Mike Watson SVT Ltd

Darren Platts