FAID provides a representative score (FAID Score) of the fatigue exposure of a worker based on the following biological determinants of fatigue:
- The time of day of work and breaks
- The duration of work and breaks
- The work history over the last seven days (this is weighted so that the most recent days provide the most input)
- The biological limits on recovery of sleep (basically, this acknowledges that you can’t bank up sleep. That is, there is only a certain amount of sleep that can be obtained in a break of certain duration at a certain time of day.)
While the FAID Score is essentially arbitrary, benchmarking studies suggest that fatigue threshold scores of 80 or below are consistent with a safe system of work for Australian industrial operations.
In the absence of a Fatigue Hazard Analysis Risk Assessment Workshop, a Peak Fatigue Threshold score of 80 can be used as a starting point.