ABSTRACT
Most matrices utilise a simple combination of the likelihood of a hazard having an adverse effect and the severity of the consequences if it did. Some use numbers to produce a risk rating, as in the example below:
Risk assessment matrix Likelihood of adverse effect
Unlikely Possible Frequent
1 2 3
Severity of consequences
Minor 1 1 2 3
Moderate 2 2 4 6
Severe 3 3 6 9
The numbers can be replaced by descriptions of the level of risk as shown in the next example:
Risk assessment matrix Likelihood of adverse effect
Unlikely Possible Frequent
Severity of consequences
Minor Low Low Medium
Moderate Low Medium High
Severe Medium High Very high
A more complex version of this approach was provided in a supplement to the May 1993 issue of The Safety & Health Practitioner, the magazine of the Institution of Occupational Safety & Health. This approach requires first the identification of the worst likely outcome in respect of each hazard i.e.:
• a fatality; • (including permanent ill
• minor injury; or • no injury.
