isk, the word brings to mind a number of different de®nitions. There is the de®nition associated with the ®nancial world, i.e., this stock a ``risky'' investment. There is the de®nition associated with the probability of an accident or injury. Even within a particular ®eld such as safety, risk has more than one meaning. Thus, to health, environment and safety professionals, the term risk must be examined in context. Risk to these professionals is generally a quanti®able and measurable quantity. It is something that can be rationally evaluated and can be mitigated. Yet, risk to the average person is something else. Risk contains a fear factor; it is perceived and it is weighed in a manner that may seem to be illogical and irrational. Why is there a difference and how does human behavior in¯uence risk decisions?
In order to address this difference, re¯ect on the following events: the John F. Kennedy assassination; the Bhopal (India) chemical accident; the crash of TWA Flight 800; the Oklahoma City bombing; and the events of September 11, 2001. These events had a drastic effect on public perception. The John F. Kennedy assassination changed many peoples view of mortality. The Bhopal chemical accident changed how the public perceived businesses, particularly chemical manufacturing operating in their communities. The crash of TWA Flight 800 impacted how vulnerable the public felt when traveling in public transportation. The event in Oklahoma City