Risk Metrics - ROSS
While waiting for the page to be complete, please see our IEEE-paper that contains a survey of risk metrics.
Individual risk per annum (IRPA)
- IRPA is the probability that a specific or hypothetical individual will be killed due to exposure to the hazards or activities a during one year. The specific hazards or activities a can be indicated by a subscript, IRPAa.
Localized individual risk (LIRA)
- LIRA is the probability that an average unprotected person, permanently present at a specified location, is killed during one year due to a hazardous event HEi at an installation.
- LIRA can be graphically displayed as iso-risk contours around a dangerous installation.
- LIRA does not account for actual exposure or population.
Potential loss of life (PLL)
PLL is the expected number of fatalities within a specific population per year.
For a workplace a with n persons, we have PLL = n x IRPAa
Fatal accident rate (FAR)
- FAR is defined as the expected number of fatalities per 100 million exposed hours. This exposure is sometimes illustrated by 1000 persons that work 2000 hours per year for 50 years - or 1000 life-years exposure (with current working hours, it will be closer to 1300 life-years.)
- FAR requires explicit definition of exposure and is therefore suited for comparison across activities.
- FAR does not distinguish between accidents with single fatalities and accidents with multiple fatalities.