The definitions described by the older OSHA and the recent ANSI standard are similar, yet, to some, contain important differences regarding the probability of serious death or injury. These definitions are as follows:
Is Personal injury a
credible possibility?
Is death or serious
injury a credible
possibility?
If hazardous situation
occurs, how likely is
accident?
If accident occurs, how
likely is death or serious
injury?
Guideline from ANSI Z535 Annex
