With this method for each risk three parameters have to be determined:
- Severity of injury linked to hazard (S);
- Exposure to the hazard (E);
- Probability of the hazard to occur when exposed (P).
These concepts are made operational so that it becomes a numerical method and a quantitative risk estimation can be made.
The probability or (mathematical) chance an incident will occur. The expectation is represented by ascribing a value from 0.1 to 10.
0,1 Next to impossible / unthinkable
0,2 Almost unimaginable
0,5 Highly unlikely, but conceivable
1 Unlikely, but possible in the long term
3 Unusual (but possible)
10 To be expected
The factor exposure indicates the duration that a risk can occur. The scale varies from 0.5 to 10.
0,5 Very rarely (less than 1x a year)
1 Rarely (approx. 1x a year)
2 Sometimes (approx.. 1x a year)
3 Occasionally (weekly)
6 Frequently (daily)
10 Constantly (multiple times a day)
The factor severity indicates the possible damage, effects and consequences linked to a hazard. The scale reaches from 1 to 40.
1 Slight effect, injury without absence through illness
3 Important, injury with absence
7 Severe, lasting injury with absence
15 Very severe, a fatal casualty
40 Disaster, multiple fatal casualties
A risk index is created by ascribing particular numerical values to the severity of possible damage, the length of exposure and the probability of a risk.
The result of multiplying the parameters defines the risk-index: R = S x E x P.
The risk-index has five categories. Based on this risk-index the appropriate (technical) measures can be determined.
Eliminate or reduce risks as far as possible (inherently safe machinery design and construction).
Take the necessary protective measures in relation to risks that cannot be eliminated.
Inform users of the residual risks due to any shortcomings of the protective measures adopted, indicate whether any particular training is required and specify any need to provide personal protective equipment.