Appendix C

Risk Communication, Risk Statistics,
and Risk Comparisons:
A Manual for Plant Managers

by Vincent T. Covello, Peter M. Sandman, and Paul Slovic

(Washington, DC: Chemical Manufacturers Association, 1988), pp. 54

Appendix C: Risk Perception Factors

Table C.1: Factors Important in Risk Perception And Evaluation


Factor	Conditions Associated with Increased Public Concern	Conditions Associated with Decreased Public Concern

Catastrophic Potential	Fatalities and Injuries Grouped in Time and Space	Fatalities and Injuries Scattered and Random
Familiarity	Unfamiliar	Familiar
Understanding	Mechanisms or Process Not Understood	Mechanisms or Process Understood
Uncertainty	Risks Scientifically Unknown or Uncertain	Risks Known to Science
Controllability (Personal)	Uncontrollable	Controllable
Voluntariness of Exposure	Involuntary	Voluntary
Effects on Children	Children Specifically at Risk	Children Not Specifically at Risk
Effects Manifestation	Delayed Effects	Immediate Effects
Effects on Future Generations	Risk to Future Generations	No Risk to Future Generations
Victim Identity	Identifiable Victims	Statistical Victims
Dread	Effects Dreaded	Effects Not Dreaded
Trust in Institutions	Lack of Trust in Responsible Institutions	Trust in Responsible Institutions
Media Attention	Much Media Attention	Little Media Attention
Accident History	Major and Sometimes Minor Accidents	No Major or Minor Accidents
Equity	Inequitable Distribution of Risks and Benefits	Equitable Distribution of Risks and Benefits
Benefits	Unclear Benefits	Clear Benefits
Reversibility	Effects Irreversible	Effects Reversible
Origin	Caused by Human Actions or Failures	Caused by Acts of Nature or God

Note: In selecting risks to be compared, it is helpful to keep these distinctions in mind. Risk comparisons that ignore these distinctions are likely to backfire (e.g., comparing voluntary to involuntary risks) unless appropriate qualifications are made (see text).

Introduction and Index

I . Effectively Communicating Risk Information

II. Guidelines for Presenting and Explaining Risk-Related Numbers and Statistics

III. Guidelines for Providing and Explaining Risk Comparisons

IV. Concrete Examples of Risk Comparisons

V. Anticipating Objections to Explanations of Chemical Risks

Conclusion

Acknowledgements

Appendix A: Concentration and Quantity Comparisons

Appendix B: Risk Comparison Tables And Figures

Appendix C: Risk Perception Factors

Selected Bibiliography on Risk Communication

Peter M. Sandman 59 Ridgeview Rd. Princeton NJ 08540-7601	Phone: 1-609-683-4073 Fax: 1-609-683-0566 Email: peter@psandman.com
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Appendix C

Risk Communication, Risk Statistics, and Risk Comparisons: A Manual for Plant Managers

by Vincent T. Covello, Peter M. Sandman, and Paul Slovic

Appendix C: Risk Perception Factors

Table C.1: Factors Important in Risk Perception And Evaluation

Risk Communication, Risk Statistics,
and Risk Comparisons:
A Manual for Plant Managers