ORCA is the acronym of Occupational Risk Calculator and is a method to assess hazards at work. It is a model that calculates occupational risks, similar to the calculation of risks for external safety. It provides insight into relative risks at work and can be used to draw conclusions about absolute risks at work.

Risk assessments are used by companies to identify the risks within their organisation. However, no method was available to quantify and prioritize these risks. ORCA (Occupational Risk Calculator) provides the quantification and prioritization.


ORCA is based on three databases that were developed and constructed, commissioned by the Ministry of Social Affairs and Employment. These databases contain information about:

  1. (underlying) causes of serious accidents that are reported to and investigated by the Labour Inspectorate (also available in a stand alone application called Storybuilder),
  2. exposure to hazards and the quality of working conditions that affect the risk,
  3. cost and effectiveness of measures to reduce risk.

The model predicts probabilities of an accident with serious consequences, which are fatality, permanent injury or recoverable injury with hospitalisation within 24 hours.

What is webORCA

WebORCA (Occupational Risk CAlculator) is the online quantitative risk model ORCA. ORCA is an instrument which enables companies to prioritise the risks of serious occupational accidents. By entering data on the actual working conditions and the duration of exposure to hazards, the risk can be calculated of the different activities carried out in the workplace or of different jobs or both. In addition the model provides suggested measures by which the risk can be reduced. The model also contains the costs of measures and makes it possible to optimise the balance between costs and benefits. The model was commissioned by the Ministry of Social Affairs and Employment (SZW) in The Netherlands and is based on an analysis of the accident reported to and investigated by the Dutch Labour Inspectorate. More information about the underlying risk model follow can be fount in the report: The Quantification of Occupational Risk.


The model has been evaluated for its technical quality by an expert panel and for its useability by a number of companies. The results of the evaluation are outlined in the brochure Veilig Werken (in Dutch).