1. Laypeople's perceptions of risk are influenced by qualitative factors like dread, catastrophic potential, and unknown risks, rather than just statistical frequencies like experts. 2. There are discrepancies between expert and layperson risk perceptions, as laypeople factor in qualitative characteristics in addition to statistical frequencies. 3. Disagreements about risk will not be resolved by evidence alone, as people interpret information in ways that confirm their existing beliefs.

1. Risk Perception Fallibility Conclusion 1 Cognitive limitations, coupled with the anxieties generated by facing life as a gamble, cause uncertainty to be denied, risks to be distorted and statements of fact to be believed with unwarranted confidence. **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

2. Risk Perception Fallibility Conclusion 2 Perceived risk is influenced (and sometimes biased) by the imaginability and memorability of the hazard. People may, therefore, not have valid perceptions even for familiar risks. **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

3. Risk Perception Fallibility Conclusion 3 Risk management experts’ risk perceptions correspond closely to statistical frequencies of death. Laypeople’s risk perceptions are based in part on frequencies of death, but there are some striking discrepancies. It appears that for laypeople, the concept of risk includes qualitative aspects such as dread and the likelihood of a mishap being fatal. Laypeople’s risk perceptions are also affected by catastrophic potential. **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

4. Factor 1: Factors Related to Dread Dreaded vs. Not Dreaded Uncontrollable vs. Controllable Global Catastrophic vs. Not Global Catastrophic Consequences Fatal vs. Consequences Not Fatal Catastrophic vs. Individual High Risk to Future Generations vs. Low Risk to Future Generations Not Equitable vs. Equitable Not Easily Reduced vs. Easily Reduced Risk Increasing vs. Risk Decreasing Involuntary vs. Voluntary Affects Me vs. Doesn’t Affect Me Not Preventable vs. Preventable **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

5. Factor 2: Factors Related to How Much is Known About the Risk Not Observable vs. Observable Unknown to Those Exposed vs. Known to Those Exposed Effect Delayed vs. Effect Immediate New Risk vs. Old Risk Risk Unknown to Science vs. Risk Known to Science **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

6. Risk Perception Fallibility Conclusion 4 Disagreements about risk should not be expected to evaporate in the presence of ‘evidence’. Definitive evidence, particularly about rare hazards, is difficult to obtain. Weaker information is likely to be interpreted in a way that reinforces existing beliefs. **Slovic, Paul, Baruch Fischhoff, and Sarah Lichtenstein. 1979. “Rating the Risks.” Environment . V21, No.3. Pp. 14-20, 36-39. April.

7. Social Constructs of Risk Socio-Economic Characteristics People’s Knowledge People’s Ignorance People’s Ability to Cope With Hazards People’s Ability to Access Help ** Vedantam, Shankar. 2003. “More Afraid Than We Should Be.” The Washington Post. March 31. P.A6.

8. Various Ways to Present Statistical Risk 1. Deaths per million people in the population 2. Deaths per million people within x miles of the source of exposure 3. Deaths per unit of concentration 4. Deaths per facility 5. Deaths per ton of air toxin released 6. Deaths per ton of air toxin absorbed by people 7. Deaths per ton of chemical produced 8. Deaths per million dollars of product produced 9. Loss of life expectancy associated with exposure to the hazard ** Slovic, Paul, and Elke Weber. 2002. “Perception of Risk Posed by Extreme Events.” Presented at Risk Management Strategies in an Uncertain World . Palisades, NY. 4/12-13/2002.

9. Risk Comparisons “ On average, cigarettes kill as many people as would die if three passenger-laden jumbo jets crashed every day, month after month, year after year. “ In one year, cigarettes kill more Americans than died in World War I, the Korean War, and the Vietnam War combined. “ The annual death toll associated with cigarette smoking is equal to that of a hydrogen bomb dropped in the heart of a city such as Miami, Kansas City, Cleveland, or wherever.” ** Warner, Kenneth E. 1989. “The Epidemiology of Coffin Nails.” In Health Risks and the Press: Coverage on Media Coverage of Risk Assessment and Health. Washington, D.C. The Media Institute.

10. How Safe is Safe Enough? Zero Level of Risk to the Public Best of available alternatives ‘ De Minimis’ 1 in 100,000 1 in 1,000,000