Posted By garyh
I have come across this when doing risk assessment eg for the COMAH report process.

Basically you assess probability & severity on a numerical scale (say 0-4 or 1-5) and then put this into a matrix. The top few "squares" will be deemed "unacceptable", the next tier is something like "unacceptable unless management measures implemented" then "acceptable but review required" then "acceptable". A good way to show this is with colouration of the tiers eg red for unacceptable.
There are many variations of this theme.

Posted By Andy Brazier
Risk tolerability is split into individual risk and societal risk. In general terms society will accept a single fatalities events that occur more frequently than multiple failure events that occur less frequently.

For example 10 deaths on the road everyday do not make the news but a single train crash that kills 10 people will. The response can be that people perceive the railways to be unsafe and start driving, thus significantly increasing their risk.

It is a complex subject, but you need to understand these two areas if you are to get a full grasp of risk tolerability criteria.

Posted By Dan dan
Link no longer exists