assessment phase, with EPA’s decision makers being an important audience at this stage. Those characterizations should include a characterization of the uncertainties in the data and analyses that underlie each of the factors that were assessed. One type of communication during the implementation phase will be the agency communicating with stakeholders to discuss its decision and the rationale for its decision, including how uncertainties affect the decision. Another part of the communication process should be the agency getting feedback on the decision and uncertainties as well as having discussions about how and when the decision will be revisited.
To develop guidance on communicating uncertainty, the Netherlands Environmental Assessment Agency relied on literature reviews, a workshop on uncertainty communication, and research by the authors of the guidance document (Kloprogge et al., 2007). The guidance emphasizes the importance of decision context. The context of a decision—that is, the characteristics of the setting in which the decision is being made—affects the communication of the decision and of the uncertainty underlying it. Box 6-2 lists some decision contexts in which the communication of the uncertainty surrounding a decision is particularly important. A complex decision based on controversial science or a decision about which stakeholders disagree will benefit from greater attention to communicating uncertainties (Kloprogge et al., 2007).
It can be especially challenging to communicate the uncertainty associated with a decision made in an emergency situation, such as a hazardous chemical spill. Under such circumstances, EPA must communicate not only with those involved in containment and cleanup, but also with members of the public who might be affected by the spill, and the communication may need to be done in coordination with other agencies, with governments, and with stakeholders such as private companies involved in the spill. Such communication, sometimes called crisis communication, is often carried out at a time when there are a number of large uncertainties about the event and its potential consequences on human health and the environment (Reynolds and Matthew, 2005). The time frame within which a decision is needed in an emergency situation can limit the time and opportunities available for communication, and the purpose of communication in such a situation can differ from traditional risk communications in that crisis communication often is principally informative (Reynolds and Matthew, 2005). Although it is generally not possible to predict the timing and extent of an emergency, the nature of many potential emergencies can, and often are, known and planned for. Communicating with stakeholders about the uncertainties that might follow an emergency during the planning for such an emergency and