Critical Steps happen every day at work and at home, purposefully. Work does not happen otherwise. If an operation has the capacity to do work, then it has the capacity to do harm. Work is energy directed by human beings to create value. But people are imperfect—we make mistakes, and sometimes we lose control of the work. Therefore, work is the use of force under conditions of uncertainty. A Critical Step is a human action that will trigger immediate, irreversible, and intolerable harm...