HSE Pill #13 - Risk Assessment Management series: Understanding Likelihood and Severity in Job Safety Analysis (JSA)
Victor D. Briz Narvaez, MIIRSM
Process & DCS Senior Operator | Industrial Engineering Professional | HSE Champion | Nebosh IGC Certified | IIRSM Full Member (MIIRSM) | Oil & Gas Industry
In our ongoing series dedicated to enhancing workplace safety through Job Safety Analysis (JSA), we now focus on two pivotal factors: likelihood and severity. These elements are not just components; they are the bedrock of an effective risk assessment, allowing us to prioritize potential hazards and implement targeted control measures. Let's dive in and unravel the critical aspects of determining likelihood and severity in the JSA process.
Prioritizing Risks: The Risk Matrix Approach
The Risk Matrix: The risk matrix is a visual tool that helps combine likelihood and severity scores to prioritize risks. It divides risks into categories such as low, medium, and high risk, making it easier to focus efforts on the most critical tasks.
Taking Action: When likelihood and severity converge, a measurement of risk is obtained (factoring the Severity/Likelihood scores), and actionable insights emerge. Higher-risk tasks demand immediate attention and more comprehensive control measures. The risk matrix facilitates informed decision-making, ensuring that resources are allocated where they can make the most significant difference.
Likelihood: Assessing the Probability of Hazards
Likelihood refers to the chance or probability of a specific hazard occurring during the execution of a task. It helps us gauge the potential frequency of an event and aids in identifying high-risk tasks that demand immediate attention.
Factors Influencing Likelihood: Consider these factors when determining the likelihood of a hazard:
- Historical data: Past incidents or near-misses can offer insights into the likelihood of certain hazards.
- Frequency of task: Tasks performed frequently may have a higher likelihood of hazards.
- Experience of workers: Inexperienced workers might increase the likelihood of errors.
Scoring Likelihood: Many organizations use a numerical scale (e.g., 1 to 5) to score the likelihood of hazards, where 1 represents "Very Unlikely" and 5 represents "Very Likely." For example, if a task involving heavy lifting has led to injuries in the past, it might receive a score of 4 for likelihood due to historical data.
Severity: Evaluating the Impact of Hazards
Severity refers to the potential impact or consequences of a hazard if it were to occur. It helps us understand the potential harm to people, property, or the environment.
Factors Influencing Severity: Consider these factors when evaluating the severity of a hazard:
领英推荐
- Potential injuries: The types of injuries that could result from the hazard.
- Property damage: The extent of damage that might occur.
- Environmental impact: Any harm to the environment that may arise.
Scoring Severity: Similar to likelihood, severity is scored using a numerical scale. A typical scale ranges from 1 to 5, where 1 indicates "Minor" and 5 indicates "Catastrophic." For instance, if a potential hazard could lead to minor cuts or bruises, it might receive a severity score of 2.
Residual Risk: Factoring in Safety Controls
Residual risk is the risk that remains after safety controls and preventive measures have been implemented to address identified hazards. It represents the level of risk that workers and the environment are exposed to despite the protective measures in place giving a metric to make the risk quantifiable, and measurable. Also, it will aid the supervisors in identifying which risks are priorities and have to be reduced.
Residual risk is calculated by combining the residual likelihood (likelihood after controls) and residual severity (severity after controls) scores. This calculation provides a clear picture of the remaining risk level.
Residual risk evaluation highlights the effectiveness of safety controls. It demonstrates the extent to which the implemented measures have reduced the overall risk to ALARP (As Low As Reasonable Practical), ensuring a safer working environment.
Evaluating the likelihood and severity of hazards properly is the key element of effective risk management. This assessment allows organizations to prioritize efforts, ensuring a safer work environment.
Complementary reading
Standards and Guidelines: Notable standards that emphasize the importance of likelihood and severity in risk assessments include ISO 31000: Risk Management, which provides a comprehensive framework, and the UK's Regulation "Control of Major Accident Hazards (COMAH) Regulations 2015".
Subscribe and stay committed to safety, stay informed, and stay proactive!