Advanced Safety Management, 3rd Edition

ADDENDUM A – 2

Risk Assessment Matrix
Severity Levels and Values	Occurrence Probabilities and Values
Unlikely (1)	Seldom (2)	Occasional (3)	Likely (4)	Frequent (5)
Catastrophic (5)	5	10	15	20	25
Critical (4)	4	8	12	16	20
Marginal (3)	3	6	9	12	15
Negligible (2)	2	4	6	8	10
Insignificant (1)	1	2	3	4	5

Numbers were intuitively derived. They are qualitative, not quantitative and have meaning only in relation to each other.

Exposure Codes: P – personnel; E – environment; D – damage – facility, equipment, business interruption; M – material, product

Severity Descriptions

C – Catastrophic:	One or more fatalities, total system loss and major business down time, environmental release with lasting impact on others with respect to health, property damage or business interruption.
Cr – Critical:	Disabling injury or illness, major property damage and business down time, environmental release with temporary impact on others with respect to health, property damage or business interruption.
M – Marginal:	Medical treatment or restricted work, minor subsystem loss or property damage, environmental release triggering external reporting requirements.
N – Negligible:	First aid or minor medical treatment only, non-serious equipment or facility damage, environmental release requiring routine cleanup without reporting.
I – Insignificant:	Inconsequential with respect to injuries or illnesses, system loss or down time, or environmental release.

Probability Descriptions ...