Communicating With the Public About Emerging Health Threats: Lessons From the Pre-Event Message Development Project

Abstract

Objectives. We sought to better understand the challenges of communicating with the public about emerging health threats, particularly threats involving toxic chemicals, biological agents, and radioactive materials.

Methods. At the request of the Centers for Disease Control and Prevention, we formed an interdisciplinary consortium of investigative teams from 4 schools of public health. Over 2 years, the investigative teams conducted 79 focus group interviews with 884 participants and individual cognitive response interviews with 129 respondents, for a total sample of 1013 individuals. The investigative teams systematically compared their results with other published research in public health, risk communication, and emergency preparedness.

Results. We found limited public understanding of emerging biological, chemical, and radioactive materials threats and of the differences between them; demand for concrete, accurate, and consistent information about actions needed for protection of self and family; active information seeking from media, local authorities, and selected national sources; and areas in which current emergency messaging can be improved.

Conclusions. The public will respond to a threat situation by seeking protective information and taking self-protective action, underlining the critical role of effective communication in public health emergencies.

Effective public communication is a crucial component of emergency response.^1,2 Timely, accurate information can help people at risk take appropriate protective measures, prevent illness and injury, reduce unnecessary care seeking, and facilitate relief and recovery efforts.^3,4

Although all public health emergencies present significant challenges for communicating with the public, emerging, unfamiliar, unidentified, or intentionally released agents, such as radioactive “dirty bombs,” chemical terrorism, and avian influenza, can pose even greater communication difficulties for public health professionals. Research and historical experience have shown that such threats have a powerful potential to generate fear, cause negative behavioral responses such as social stigma,⁵ and undermine confidence in social institutions. Such reactions complicate efforts to manage an emergency and make the already daunting task of rapidly conveying complex self-protection information even more difficult.^6–8 Furthermore, agencies can face unprecedented demands for information even as resources are stretched thin as they attempt to respond to the situation.⁹

Aware of the communication challenges posed by the 2001 anthrax letter incidents, the Centers for Disease Control and Prevention (CDC) established a cooperative agreement with the Association of Schools of Public Health in 2002 to support a major study of emerging information needs and information-seeking strategies of members of the public facing emerging threats. Between 2002 and 2006, we conducted the Pre-Event Message Development Project (PEMDP), which assessed communication needs of the public in the event of emerging threats.

The PEMDP study teams examined communication needs related to 4 agents—radioactive materials, plague (infectious agent), botulinum toxin (noninfectious agent), and VX (nerve agent)—in 3 threat categories—radioactive agents, biological agents, and chemical agents (Table 1). Each agent was studied independently and as a representative of the broader category to generate agent-specific communication recommendations and general insights into emerging threats.

TABLE 1.

Agent Categories, Definitions, Examples, and Risks: Pre-Event Message Development Project, 2002–2006

Agent Categories	Operational Definitions	Examples	Risks
Biological agents	Viruses, bacteria, or other germs used to cause illness or death among people, animals, or plants. Biological agents can be spread through the air, through water, or in food. Some agents, like the smallpox virus, can be spread from person to person, and some, like anthrax, cannot.	Anthrax, botulism, plague, smallpox, tularemia, avian influenza	Biological agents have the potential to cause excess morbidity and mortality and a major public health impact. They vary in terms of the severity of illness or likelihood of death because of exposure.
Chemical agents	Toxic chemical substances that may be accidentally or intentionally released. Exposed individuals either have direct physical contact with or breathe in the substance. Effects are not infectious.	Mustard gas, cyanide, chlorine, sarin gas, VX	Chemical agents are categorized according to their effects on the human body. Blistering agents cause pain, swelling, and itchiness on the skin and in the nose, mouth, and throat. Blood agents deprive the blood and organs of oxygen. Nerve agents damage the nervous system and affect movement and breathing. Choking agents attack the respiratory system and cause difficulty breathing.
Radioactive agents	Release of radioactive materials, potentially exposing people to radiation or resulting in radioactive contamination of structures, areas, objects, or people.	Could be released using a “dirty bomb,” which combines conventional explosives and radioactive materials	The most serious injuries from a dirty bomb, including burns or bleeding, are likely to be from the conventional blast itself. However, depending on the incident, substantial numbers of people could become externally or internally contaminated with radioactive materials.

Source. Adapted from http://www.bt.cdc.gov/firsthours/intro.asp.¹⁶

We present the overarching findings of the PEMDP here for the first time; agent-specific results are published elsewhere.^10–15 By examining the results across a range of threats and systematically comparing the findings with comparable research, we hope to provide valuable general lessons for risk communication in public health emergencies. (All project reports, publications, and message materials are publicly available at http://www.bt.cdc.gov/firsthours/intro.asp.¹⁶)

Our aims for the PEMDP were to (1) investigate the general public's current knowledge, concerns, and potential responses to threats and to pretest existing agent-specific informational materials developed by the CDC (year 1); (2) develop and pretest new message materials on the basis of the first year's findings (year 2); and (3) assess study findings in comparison with relevant published research (year 3). Partner schools (Saint Louis University, the University of California at Los Angeles, the University of Oklahoma, and the University of Alabama at Birmingham) established a common protocol for all research. We standardized recruitment protocols, instruments, coding guides, and reporting templates across institutions. Each university's institutional review board approved original research.

METHODS

Formative Research

All study teams conducted formative research regarding all 4 agents. On the basis of respective areas of expertise, each study team concentrated on 1 agent in data analysis, reporting, and message development. In years 1 and 2, study teams conducted formative research with members of the public segmented by ethnicity and by urban or rural residence. Formative research from year 1 informed agent-specific audience assessments that guided the writing, design, and pretesting of radio, television, and print materials in year 2.

The PEMDP conducted focus groups and interviews with members of 9 public audience segments: rural and urban Whites, African Americans, and Hispanics; rural American Indians; urban Asians; and urban intermediate and advanced English as a second language students. Purposive sampling ensured adequate representation of all groups. Recruitment sought to ensure broad representation in terms of age, socioeconomic status, education level, and gender across the study sample. Collaborating community service agencies or professional recruiters recruited study participants from their service areas, or study team members recruited from databases of past study participants. Only adults were permitted to participate in the study. Individuals with a history of trauma or psychiatric illness or whose relatives or friends were killed or injured in a terrorist incident were excluded. Participants were compensated for their time.

Trained interviewers conducted focus groups and interviews in community settings and university facilities. We conducted focus groups and interviews in the 4 regions in which the schools are located. Focus groups and interviews were conducted in English with the exception of Hispanic focus groups in year 1, which were conducted in Spanish.

Focus group guides asked participants about current knowledge of different threat categories. A 4-stage hypothetical agent-specific scenario followed in which the release of an unidentified agent is threatened, release of the agent occurs, the agent is identified, and informational materials are provided (Table 2). At each stage, participants were asked about their emotional and behavioral response, concerns, information needs, and information-seeking strategies during the event. Participants were also asked about their confidence in the official response to the emergency. Focus group and cognitive response interview guides assessed responses to the draft message materials and media, including comprehension, missing information, emotional responses, perceived credibility, response efficacy, self-efficacy, and recommendations for improvement (Table 3).

TABLE 2.

Sample Scenario of a Hypothetical Plague Release in St. Louis, Missouri

Scenario Sequence	Discussion Guide Verbatim Language
Part 1: Nonspecific agent	You wake up about 7 am on a Tuesday and turn on the local news to hear that President Bush has raised the Homeland Security Advisory System threat level to severe (red). The president and his advisors report that this change in the national threat level is based on knowledge of a credible threat that a terrorist group may be planning a biological attack in St. Louis. Officials suspect that the attack may involve a biological weapon.
Part 2: Symptoms	A week later, early on a Monday afternoon, you turn on the radio and hear that 15 people in St. Louis have presented at local emergency rooms and doctors’ offices with fever, headache, weakness, and rapidly developing pneumonia with shortness of breath, chest pain, cough, and bloody saliva. Although the cause has not been confirmed, these symptoms are consistent with plague. Plague is a disease that can infect the lungs and may spread from person to person through the air.
Part 3: Specific agent + symptoms + response	Later that same day, you turn on your TV to find that a local government official has issued a statement. She confirms that there has been a deliberate release of a biological agent in St. Louis and that the agent has been confirmed to be the one that causes plague. It was believed to have been released at a shopping mall into the air. So far, there are 30 presumed cases; however, more persons in St. Louis are potentially infected. Local health workers and emergency personnel are working to contain the problem by shutting down the mall, figuring out who was there, and calling for the potentially infected to seek medical treatment.
Part 4: Release of information	Local officials release information with recommendations for steps you can take to protect yourself from plague.

TABLE 3.

Research Topics and Sample Questions: Pre-Event Message Development Project, 2002–2006

Research Topic	Sample Questions
Formative research topics and questions
Preevent knowledge, attitudes, and responses	What is a biological threat?
General knowledge about basic health science as it relates to different threats	How can it be transmitted?
Emotional response to an attack	Tell me how you would feel about this news?
Actions in response to an attack	What would you do?
Terrorism information needs	What would you want to know?
Terrorism information-seeking behavior	Where would you go to get more information?
Confidence in the government and public health response to a potential attack	How confident are you that there are systems in place that will respond in a way that keeps you safe?
Materials pretesting topics and questions
Comprehension	What do you think are the main points of these fact sheets?
Emotional response	How do these fact sheets make you feel?
Believability	How credible is the information in the fact sheets?
Self-efficacy	How confident are you that you can carry out these recommendations?
Response efficacy	How confident are you that the actions recommended in the fact sheets will keep you safe?
Recommendations for improvement	Do you have any other recommendations to make these fact sheets better or more useful to you?

Audiotapes of focus groups and interviews were transcribed and entered into qualitative data analysis programs for coding and analysis. Coding guides derived from question topics allowed unanticipated themes to emerge. Trained pairs of analysts coded and recoded transcripts until domains were “saturated” and common themes emerged, providing an auditable trail of findings.^17–19 Pairs of researchers check-coded each transcript, reviewing their work to discover and resolve disagreements. Statements associated with relevant codes were extracted from each transcript and analyzed for meanings. These meanings were clustered into themes that could be analyzed and reported on across focus groups and interviews.²⁰ Analysts used matrices summarizing results by theme and group to identify similarities and differences across audience segments, regions, and place of residence and prepared agent-specific reports.¹⁹

Participant Characteristics

In year 1, the study teams conducted 37 focus groups with 444 participants. In year 2, the study teams conducted 42 focus groups with 440 participants and 129 cognitive response interviews; the total sample size was 1013 (Table 4). For the total sample, the mean age was 44 years. Two thirds of the sample (65%) were women. About one eighth of the sample (13%) had less than a high school diploma; almost half had completed high school (18%) or some college (27%); more than one third had a college degree (23%) or higher (13%); 6% opted not to provide information on education level.

TABLE 4.

Demographic Characteristics of Study Participants: Pre-Event Message Development Project, 2002–2006

Characteristics	Year-1 Focus Groups	Year-2 Focus Groups	Year-2 Cognitive Response Interviews	Year 1 and Year 2 Combined
No. of participants	444	440	129	1013
Mean age, y	44.24	44.72	39.78	43.88
Gender, %
Men	39	29	33	34
Women	61	68	67	65
Data missing	< 1	3	0	1
Education, %
Less than high school	9	3	4	6
Some high school	9	6	6	7
High school diploma or GED	18	19	13	18
Some college	25	27	32	27
College degree	17	28	30	23
Graduate degree	11	15	15	13
Data missing	11	2	0	6
Race/Ethnicity, %
African American	21	24	28	23
American Indian/Alaska Native	10	10	12	10
Asian/Pacific Islander	14	22	14	18
White	21	24	22	22
Hispanic	30	17	23	24
Other	3	0	0	1
Data missing	1	3	0	2
Language in home, %
English	64	79	83	73
Spanish	20	7	10	13
Bilingual/English and other	8	0	8	3
Other	7	11	0	9
Data missing	1	2	0	2
Marital status, %
Single	28	31	45	26
Married or living with partner	43	42	33	43
Divorced or separated	12	17	13	17
Widowed	8	7	7	8
Data missing	10	4	1	6
Children, %
Yes	66	58	63	62
No	30	38	36	34
Data missing	5	4	1	4
Employment, %
Yes	53	61	70	59
No	39	36	28	36
Data missing	8	3	2	5
Family income, %
≤ $10,000	17	14	14	13
$10 000–$19,999	19	16	20	17
$20 000–$29 999	12	18	14	16
$30 000–$39 999	7	12	12	10
$40 000–$49 999	6	9	10	8
$50 000–$59 999	4	4	7	5
$60 000–$69 999	5	4	5	5
$70 000–$79 999	1	4	5	3
$80 000–$89 999	1	1	2	2
$90 000–$99 999	2	2	2	2
≥ $100 000	5	5	2	4
Data missing	21	11	6	15

The race/ethnicity of the sample was consistent with the purposive sampling: 23% were African American, 10% were American Indian or Alaska Native, 18% were Asian or Pacific Islander, 22% were White, and 24% were Hispanic. Seventy-five percent of the sample (73%) spoke English at home, 13% spoke Spanish, and 12% were bilingual or spoke another language at home. Almost half of the participants were married or living with a partner (43%), one quarter (25%) were divorced, separated, or widowed, and about one fourth was single (26%). More than half the sample had children (62%) and were employed (59%). Less than half the sample earned a family income less than $30 000 (46%).

Verification Analysis

In year 3, verification analysis was conducted to assess how the PEMDP results compared with research on similar topics, to understand why any contradictions appeared, and to specify instances where the PEMDP identified new results. Researchers searched multiple databases using search terms to obtain articles or reports on research that corresponded with the PEMDP. Peer review articles as well as available organizational research and public polling reports were included. We selected 729 articles in the first round of inclusion to represent available research published through June 2005. For the second round of inclusion, research teams used standardized criteria to select from the first round results. We selected 131 articles on risk communication and public (not professional) perceptions about disasters, disease outbreaks, and terrorism for the verification analysis.

Each article was coded according to specific categories in a standardized database: study method (qualitative or quantitative), type of data collection, threat, topic area, subject terms, and findings. Study teams reviewed all articles on threats comparable to their priority agent. Analysts looked for similarities and differences between existing research and the findings of the PEMDP. We synthesized the results of verification analyses across the 4 PEMDP agents for presentation here.

RESULTS

We anticipated that participant responses would vary according to different kinds of agents or agent categories, but overall, the findings were consistent across agents and populations and with previous research on emergency risk communication, except where noted. The project also produced important new findings that expand our understanding of emerging public health threats and the challenges they pose for effective communication. Table 5 presents key findings of the study and implications for communication.

TABLE 5.

Confirmatory and Unique Study Findings and Implications for Emergency Communication: Pre-Event Message Development Project, 2002–2006

Topic	Confirmatory Findings	Unique Findings	Implications for Emergencies
Pre-event knowledge	The public has limited knowledge of radioactive, chemical, and biological agents.	There is limited understanding of the differences between threats. Urban residents are more knowledgeable; rural residents perceive lower threats in their areas.	Assume the public does not know basic information about the threat. Provide basic information about transmission, exposure, symptoms, treatment.
Information needs in an event	The public needs detailed information about the threat, official response, and steps to take to protect self and family, specifically, how to avoid exposure, recognize symptoms, and treat effects.	Information needs were consistent across region and agent. The public wants to know what to do if driving in a car and what to do to protect pets.	The public will look for detailed information on the nature of the threat, action steps to stay safe, and government response. Action steps and attentiveness depend on proximity to event.
Information seeking in an event	The public will turn to broadcast media for emergency information, as well as local information sources, including emergency, law enforcement, and health professionals. Individuals use multiple sources to validate information.	Rural populations look to local authorities first for emergency information; urban residents seek information from broadcast media first. Rural residents report greater trust in local officials. Individuals near an emergency turn to local sources first, then national.	Both broadcast media and local officials need to be prepared with accurate information in an emergency. Consistency across sources establishes accuracy and veracity of information.
Public actions in an event	Priority actions are to seek information about the emergency and to protect self and family. Adherence to directives such as shelter-in- place will vary.	None.	Quickly provide information regarding specific protective actions and explain why actions are protective.
Emotional response in an event	Emerging health threats provoke strong emotions, including fear, shock, and anger. Members of minorities may be less confident in protective actions.	Individuals at greater risk (e.g., disabled) may have heightened concerns about their ability to respond. Increased information decreases fear and anxiety.	Anticipate emotional response. Include action steps in public communication to reassure the public, especially those close to the threat.
Confidence in government	The public questions the readiness of local, state, and federal government agencies to handle emergencies. Distrust is greater among members of minority communities.	Members of the public have more confidence in local than federal authorities and are more likely to trust first responders than politicians.	Officials can foster trust by being open about official response, available information, and protective actions.
The content of emergency message materials	None.	The public responds positively to practical, concrete action steps, clear and accurate information, and consistent and simple messages. Unfamiliar terms cause confusion and uncertainty.	Emergency-response communication should include accurate information about steps people can use to keep them-selves and their families safe. Messages should be clear and simple, and unfamiliar terms need to be explained.
Response to media	The public generally perceives the news media as useful providers of emergency information, despite concerns about sensationalism.	In general, complete and accurate information about protective actions reduces fear and anxiety.	News coverage and information about emergencies have emotional effects. Actionable messages are reassuring.

Pre-Event Knowledge

PEMDP findings indicated that members of the general public have a limited understanding of biological, chemical, and radioactive materials hazards, consistent with past quantitative research, including representative national surveys, about infectious disease outbreaks, disasters, and terrorism.^21–27 The PEMDP analysis identified several novel results: focus group participants often struggled to understand differences between categories of agents, for example, between infectious and noninfectious agents or between radiological and nonradiological agents. Urban groups appeared more knowledgeable than did rural groups. Rural groups tended to be less concerned about the threat of terrorism, thinking that urban areas were more likely to be targeted.

Information Needs in an Event

Faced with an emergency, members of the public need detailed information about the nature of the threat, how to protect themselves and their families, and the official response to the situation. Across the 4 agents studied, the demand for information about protective actions was consistent: participants wanted to know how to avoid exposure, recognize symptoms, and treat effects. PEMDP findings were generally consistent with past survey and qualitative research on information needs in an event,^9,23,28–35 including national polling data.²⁹ The PEMDP looked for differences across regions, whereas previous surveys presented results aggregated at the national level or specific to 1 region (e.g., New York City). The PEMDP found that information needs were consistent across all regions and population subgroups studied.

The open-ended questions in the PEMDP allowed unanticipated responses to emerge. Two important themes were identified: concerns about what to do if an individual is driving in a car when an emergency occurs and what to do to protect pets from exposure to toxic agents. Few government materials on emerging threats included such information at the time data were collected, but new materials have begun to incorporate these elements as a result of the PEMDP research.

The PEMDP focus groups also indicated that people want as much protective information as possible. This contradicts the results of one survey in which respondents complained about too much information.³³ However, that survey inquired about information needs before an event, whereas the PEMDP asked about information needs during an event.

Information Seeking in an Event

The PEMDP found that the public will turn to the broadcast media, especially television, for emergency information first, confirming survey and qualitative research.^34,36–45 Print news and the Internet are also viewed as important sources of information, and the radio was seen as valuable in scenarios in which electric power is out or when people are driving. In addition to media sources, PEMDP findings suggest that the public will also seek information from respected local sources and networks, including emergency and law enforcement personnel and medical and public health professionals, who are seen as having relevant expertise. This is also consistent with previous research.^9,28,46–52 PEMDP findings also confirmed results of a study that found that people would check a number of sources to validate information.⁴⁵

We also discerned important new findings regarding information seeking in an emergency. Most notably, we found that rural populations turn to local authorities first, whereas urban residents turn to broadcast media first. Caused in part to the relative scarcity of local broadcast media in rural areas, rural individuals rely more on the telephone for information. Rural participants reported more familiarity with and trust in local officials as information sources. Members of the public living near an attack will turn to local media first and then national media. Again, radio is an important backup when power is out or individuals are driving.

Our results contradicted those of 2 studies. The first study found that cable television channels were preferred,⁴² whereas the PEMDP found that local television channels tend to be favored. The PEMDP focus groups referred to a hypothetical local event, however, whereas the survey asked about a national event. In the second study, a nonrepresentative sample indicated that the Internet was a favored source.²⁸ PEMDP participants reported that the Internet was less preferred during a crisis and more likely to be used later.

Public Actions in an Event

The PEMDP found that priority actions of the public were to seek information about the emergency and to protect self and family, confirming research following actual emergencies²⁹ and quantitative and qualitative research.^25,29 Our results were also consistent with a number of surveys reporting that significant numbers of people—in some cases up to 90%—indicate they may not comply with official directives to shelter-in-place or evacuate.^41,53–55 The status of family members, especially children in school, and knowledge of preparedness plans for family members in other locations are determining factors for adherence to shelter-in-place directives.^{41,53,54,56–58}

Emotional Response in an Event

PEMDP findings showed that situations involving emerging health threats can produce strong emotional responses, including worry, fear, shock, anger, and disbelief, which is consistent with past survey and qualitative research.^39,59,60 Groups at specific risk, such as those living near hazardous facilities or disabled or older adults, had heightened concerns about safety and their ability to take protective action. The focus groups also demonstrated that minority groups, especially American Indians and Hispanics, tend to be more fatalistic and have less faith in the efficacy of protective actions and are more likely to lose hope, which is consistent with past research. ^39,59,60

Confidence in Government

PEMDP findings showed that the public questions the capacity and readiness of the local, state, and federal governments to handle terrorist disasters, which is consistent with past survey and qualitative research.^{31,41,54,61–65} The PEMDP also corroborated published findings that suggest that distrust of the government is more pronounced among minority communities, including African Americans and Hispanics, who fear unequal treatment in a disaster.^50,66,67 The PEMDP results were consistent with a quantitative study showing that openness in government response about an event is important in fostering trust.²⁶

The Content of Emergency Message Materials

A unique contribution of the PEMDP project was the assessment of draft television, radio, and print materials about the threats. Many general findings from this exercise were consistent with best practices for general risk communication.⁶⁸ Participants responded positively to practical, concrete action steps, clear and accurate information, and messages that were consistent and simple. Television messages were more likely to get the attention of participants, but print materials were considered more complete.

At the same time, the interviews identified important sources of confusion and uncertainty (i.e., the term “shelter-in-place”) in current government messaging efforts.¹¹ Non-English speakers consistently had problems understanding communications and feared that they would miss vital instructions.

Response to Media

The PEMDP found that media coverage of emergencies is generally perceived as a source of useful information, confirming past research regarding public perceptions about broadcast media in an emergency.^34,36–39 However, many members of the public are skeptical about the motives of the media because they perceive the media to have a tendency to sensationalize reports. The PEMDP confirmed experimental research showing that some news coverage of emergencies can increase levels of fear.⁶⁹ In the PEMDP pretests, television and radio spots caused some fear and anxiety, which was attributed to doubts about completeness of messages, credibility of sources, and uncertainty. Overall, however, we found that complete and accurate information conveying protective actions reduced levels of fear and anxiety.

Non-English speakers expressed concerns that information would not be available in their native language. Hispanic participants indicated that they would listen to both Spanish and English media to cross-validate information.

DISCUSSION

The public's understanding of biological, chemical, and radiological threats and the differences between categories appears to be limited. In an emergency, segments of population across ethnicity and region demanded information about protective actions. Members of the public say the immediate actions they will take in an emergency are active information seeking from media and local authorities and protection of self and family. Openness in government response about an event, concrete and accurate information, and consistency across sources foster confidence and trust. Key terms often found in emergency messages are often misunderstood. Likewise, members of the public question the feasibility of some emergency instructions.

The design of the PEMDP enabled study teams to identify differences between audience segments. Results were consistent across agent categories and segments overall, with a few exceptions. Rural populations were more likely to seek information from local authorities first, whereas urban residents would rely more on the mass media. Multiple communication issues pertain to minority groups, the most important of which are greater levels of distrust and higher levels of fatalism.

By combining a synthesis of research across threat categories and a systematic literature review, concerns about generalizability and adherence can be addressed. First, the PEMDP's findings of a common set of public responses and information needs in biological, chemical, and radiological events suggest that it is possible to generalize to a range of emerging threats. Second, our research has given us an in-depth understanding of public response to such threats. Our data, supported by the verification analysis findings, suggest that the public will respond to a threat situation by seeking protective information and taking self-protective actions, although these actions may not always be consistent with the public good or public health directives. This further underlines the critical role of effective communication in public health emergencies.

Limitations

Limitations inherent in focus group and interview research are introduction of bias and constrained generalizability of results. Study participants made up a nonprobability sample of audience segments within the general population, limiting the ability to generalize about the public at large. Focus group and interview data do not allow researchers to statistically control for demographic determinants such as education and income. Such methods rely on the skills of trained moderators and analysts to minimize introduction of bias.

The PEMDP teams adopted multiple measures to reduce potential bias and ensure reliability and validity. Standardized protocols ensured comparability of data across institutions. The scale of the PEMDP made possible the collection of data from over 1000 respondents from 7 states in 4 different US regions. Efforts ensured inclusion of minority groups.

The verification analysis was undertaken to test PEMDP results against research using multiple methods to answer comparable questions. The analysis combines the rigors of a systematic review of the literature with a synthesis of PEMDP results across categories of threats. PEMDP results were generally consistent with or complemented the existing literature. The analysis also made new findings possible.

Conclusions

The PEMDP provides valuable lessons for communication in public health emergencies, prompting the following recommendations for agencies and professionals seeking to inform the public about biological, chemical, and radiation threats.

First, messages should emphasize simple, practical steps and basic information about the threat. They must rapidly provide people with clear instructions on self-protection measures and foster self-efficacy. Messages should be simple enough for people to understand under high-stress conditions when people cannot process information well, and action steps provided should appear feasible. Authorities must let people know specific protective actions and explain why these actions will keep them safe. Authorities must distinguish between and provide pertinent information to groups at different levels of risk (e.g., on the basis of proximity to the event). Spokespersons with credibility on health issues should deliver the messages.

Second, messages must be disseminated quickly. Information seeking for protective actions will be one of the first steps taken by individuals. The media can facilitate government officials’ emergency risk communication. Members of the public living in the area in which an emergency takes place will look to both local broadcast media and local authorities for information. People compare sources to validate the veracity and accuracy of this information, so consistency across sources is vital. Collaboration and integration of agencies responsible for risk communication preparedness before, during, and after an event can make this possible. Officials can foster trust by being open about official response, the information available, and protective actions during an emergency. All levels and areas of government (especially local officials and agencies with health expertise) should be involved in emergency risk communication.

Effective emergency messages are not a panacea for the challenges posed by emerging public health threats. Nevertheless, by rapidly providing people with the information they need, they can reduce morbidity and mortality and help maintain public confidence. In this regard, the lessons of the PEMDP may be useful as emergency planners and responders grapple with the challenges of emerging public health threats in coming years.