A small improvement in the method for assessment of probability
1. Risk assessment is an important exercise in any OH&S Management System for taking preventive action and assuring safety of people.
2. The procedure for Risk Assessment is freely available from many sources.For example the following sites provide good guideline.
3. Risk is defined as the net result of probability and consequence; r=pc.
4. As part of assessment, what is suggested in the procedure for assessing probability is to select from a table such as the following:
Probability : (as per www.uq.edu.au/ohs/pdfs/ohsriskmgt.pdf)
Almost certain The most likely and expected result if the hazard –
event takes place.
Quite possible Quite possible, would not be unusual, even 50/50
Unusual but possible Unusual but possible sequence or coincidence
Remotely possible Remotely possible coincidence
Conceivable but unlikely Has never happened after may years of exposure,
but is conceivably possible
Practically impossible. Practically impossible, has never happened before
5 My view
P being one of just two items in the equation, and the assessment having a strong bearing on assurance for people’s safety, it is considered desirable to make the assessment a little more objective.It is true that arbitrariness could not be completely eliminated. But it could be reduced to some extent by taking the analysis a bit further.
6. In view of the above, the line of thought is as follows: An assessor is making the assessment at certain point of time.The assessor is making an assessment with respect to certain situation/location. The likelihood of an undesirable event happening would depend on certain factors existing in the situation/location.
Hence it is felt that the assessor must list the general and specific factors having influence on an accident, visualize the various states in which the factors likely to exist anywhere, identify each factor-wise the state which is prevalent in the location and, based on the combination of the states of the factors, arrive at conclusion regarding probability.
7. The following Table is provided herewith as an example:
|Sl.No||Factors that have influence for an accident||Probability of Occurrence and Numerical value assignable|
|Will Happen||May Happen||Equal Chance||May not happen||Will not happen|
|Numerical value Assignable|
|State of the Factor|
|1||Occurrence of Incidents||Frequent||*||Noticeable||Rare||Nil|
|2||Occurrence of Accident||Every Year||*||Last year||*||Never|
|3||Condition of work environment||Bad||Not satisfactory||Satisfactory||Scope for improvement||Good|
|4||Exposure of persons||Long||*||Medium||*||Short|
|5||Permit system(Hot permit, Height permit etc.,)||Does not exist||*||Exists not followed always||*||Exists and followed|
|6||Supervision||Does not exist||Short period||Intermittent||frequent||Continuous|
|8||Engineering control||Nil||Exists but Not reliable||*||*||Exists and reliable|
|9||Use of PPE||Not a practice||*||*||*||Completeadherence|
* To be described similarly
8. We can also add ‘weight’ to each factor, assign numerical values for the ‘states’ and arrive at a ‘score’ for the overall assessment.
9. The above method involving factorization, factor-wise description of the likely scene in general and selecting the scene that exists in the location at the assessment time , it is felt, may be adopted for any other assessments also, by adapting it suitably.
10. A small step to make the risk assessment a bit more reliable! Or shall we call it a step for ‘process refinement’?