Uses and abuses of risk assessment

The value of hazard analysis and risk assessment in investigating and managing the safety and environmental performance of process plant has been demonstrated over a number of years. There is an attractive simplicity in the concept of assessing risks, comparing them with acceptability criteria, and making decisions based on the results. This can lead to requirements for risk assessments to be undertaken in inappropriate circumstances, to unsound application of risk assessment results, or to undue reliance on them at the expense of more fruitful approaches. Strengths and limitations of hazard analysis and risk assessment are reviewed, including the steps of hazard identification, hazard analysis, consequence and frequency assessment, criterion setting, and systematic risk reduction. The strengths include the systematic approach, narrowing of uncertainty, ranking of priorities, and increased understanding. The limitations include the chance of overlooking important hazards or routes to a hazardous situation, dubious data and calculation methods, the philosophical and debatable nature of criteria, difficulty of verification of assessed risks, and the sheer volume of work required. The appropriateness of various possible applications is considered in the light of the strengths and limitations.