Journal of Ergonomics
Open Access

Safety and Health Risk Assessment-Expanding Severity and Likelihood Codes

Venkataraman N^{* *}Correspondence: Venkataraman N, Department of Philosophy, FIDES Global, Purvis Street, Singapore, Tel: +65 81830628, Email:

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Introduction

The risk associated with any work activity depends on the severity of an accident or ill health that may occur, and the likelihood of its occurrence the safety and health risk associated with any work activity depends on the severity of an accident or ill health that may occur, and the likelihood of its occurrence [1].

Risk depends on all three factors: Hazard, vulnerability, and exposure. Risk is the estimated impact that a hazard would have on people, services, facilities, and structures in a community [2]. It refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage all safety and health risks at work can be controlled, and all accidents or ill health can be prevented. Safety and Health (S and H) risk management is a process by which the organization’s management assesses the risks, determines the control measures, and takes appropriate actions to reduce such risks. Anything that has the potential to cause harm is generally defined as hazard.

The combination of the likelihood of an occurrence of a hazardous event or exposure(s) and severity of injury or ill health that can be caused by the event or exposure(s) is termed as risk. Different models use different definitions for severity and likelihood, which are highlighted below [3].

Risk Assessment Code (RAC) a hazard number ranking system from 1 (the highest level of risk) to 5 (the lowest level of risk). Risk Assessment Matrix (RAM)–A tool used to assign RACs. Likelihood Code (A through D) indicating the probability or chance of an event actually occurring is shown in Table 1 [4].

Table 1: Likelihood code.

Consequence Code–Code (I through IV) indicating the severity of consequence resulting from exposure to a hazard is shown in Table 2 [5].

Table 2: Severity code.

The SEP model defines Risk (R)=Severity × Probability × Exposure or R=S × P × E. Here a third dimension of Exposure is given. Following Table 3 summarises the SEP model [6].

Table 3: SEP model.

Other model considers possible harm to employees, contractors, members of the public, those using products and services and anyone else affected by the activity, such as neighbours other consideration is given for persons who could be affected in different groups, such as young or inexperienced workers, pregnant workers, workers with a disability, migrant workers or ageing workers [7].

As safety and health is beyond traditional risk, it is important to be aware that human failure is not random understanding why errors occur and the different factors which make them worse will help you develop more effective controls. There are two main types of human failure: Errors (Some errors are slips or lapses, often "actions that were not as planned" or unintended actions, other errors are mistakes or errors of judgement or decision-making where the "intended actions are wrong" i.e. where we do the wrong thing believing it to be right) and violations (non-compliances, circumventions, shortcuts and workarounds) differ from the above in that they are intentional but usually well-meaning failures where the person deliberately does not carry out the procedure correctly).

A violation is a deliberate deviation from a rule or procedure [8].

A three-dimensional method, utilizes the traditional likelihood (Y-axis) and severity (X-axis), while adding a new, third dimension, as the Z-axis, and referred to as the level of control [9]. One of the step in risk assessment is to consider as who might be harmed and how, such as how your employees could be harmed by business activities or external factors [10].

Translating strength of controls into likelihood, the problem remains of associating likelihood with strength of potential controls. In system concept development and in early decisions about the development process (e.g., where to invest resources), an estimate of the potential strength of designed controls for the scenarios would be used to assess likelihood. Various strategies might be used to rank the strength of potential controls as shown in Table 4 [11].

Table 4: Strength of controls.

A guide to severity rating described as shown in Table 5 [12].

Table 5: Severity rating.

A guide to Likelihood rating described as shown in Table 6 [12].

Table 6: Likelihood rating.

According to McGregor, theory X person assumes the work is inherently distasteful to most people, and they will attempt to avoid work whenever possible and theory Y presents an optimistic view of the employees’ nature and behaviour at work. Thus theory Y person is likely to cause an incident, while theory X person is more likely to cause incidents [13].

Work attitude not only affects how well people do their job, but it also affects how safe they are when doing it. Positive people usually perform better in the workplace because they maintain an open mind and consider the outcome of their behavior [14]. Negative people, on the other hand, complain about everything, including having to practice safety. A negative work attitude can lead to unsafe work habits and accidents. Negative workplace behaviour, such as workplace bullying, is an important work-related psychosocial hazard with the potential to contribute to employee ill health.

There is a need to expand the statements used in severity and likelihood so as to make a comprehensive risk assessments.

Objective

Key objective of this paper is to have an inclusive definition for severity and likelihood for assessing safety and health risk.

Methodology

3 step approach

Different models have varied definitions for severity and likelihood for a safety and health risk assessment. Following 3 steps are adopted for this model (Figure 1).

Figure 1: 3 step process for risk assessment.

Step 1: Summarizing the broad parameters used for severity and probability/likelihood are:

• Severity-Injuries to people and property damage.

• Likelihood or probability level of controls, likely to occur, behaviour/culture, exposure levels, morale, attitude and number of people likely to be affected, and training. Level of controls includes training, well written procedures, supervision and instructions

Step 2: Creating a severity and likelihood codes/rankings. For this exercise, 5 × 5 matrixes are adopted. This step is to have a severity and likelihood table. It identifies the broad definitions and statement that can be used for likelihood and severity respectively (Tables 7 and 8).

Table 7: Likelihood statements.

Table 8: Severity statements.

Step 3: Evaluate risk using the matrix (in numbers and words) are shown in Tables 9 and 10.

Table 9: Example of a common 5 × 5 risk matrix with a mix of numeric and descriptive ratings [5].

Table 10: Example of a common 5 × 5 risk matrix with a mix of words and descriptive ratings [5].

Mathematically, Risk can be expressed as f (R)=f (L, S) …....……. (1)

Where R is Risk, L and S are Likelihood and Severity.

Expanding equation 1, we get

R=L × S ……………….. (2)

Risk is directly proportional to the product of likelihood and severity.

When risk has to be controlled or reduced, it should be noted that L and/or S has to be reduced. Traditional approaches to risk controls include the hierarchy of controls as shown below in Figure 2.

Figure 2: Hierarchy of controls.

Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process [15]. Well-designed engineering controls can be highly effective in protecting workers and will typically be independent of worker interactions to provide this high level of protection. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard. These are examples of reducing severity. Administrative controls and PPE are frequently used with existing processes where hazards are not particularly well controlled. Administrative controls and PPE programs may be relatively inexpensive to establish but, over the long term, can be very costly to sustain. These methods for protecting workers have also proven to be less effective than other measures, requiring significant effort by the affected workers.

These are examples of reducing likelihood. Once the risk reduction strategy is identified, say to reduce L or S, Tables 7 and 8 may be used to determine, as which suitable control measures are reasonable and practical that can be applied.

Results and Discussion

When computing likelihood or severity statements/code, it should be evaluated against all possible attributes. In situations, where one of the attributes falls in different codes, highest code should be taken. For example, if morale of staff is very high, but there are no controls, likelihood should be taken as almost certain (5). Similarly, for severity.

There may be other attributes such as duration of exposure, which can be decided by the team conducting the risk assessments. This model is based on 5 × 5 matrix of risk assessment. Should anyone wish to use other matrix such as 3 × 3, statements or codes mentioned in Tables 7 and 8 have to be modified.

Conclusion

Any organisation’s responsibility is to ensure risk is eliminated or controlled to as reasonable as practical. The key to risk assessment is evaluating severity and likelihood of the hazard to occur. Having an inclusive definition for severity and likelihood, risk assessment will be more realistic and accurate. This model can be used when impact to environment is to be considered. This expanded definition can be used for other types of matrix.

References

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