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.