What are the hospital infection control issues associated with a SARS outbreak, and what are the most effective approaches to address these issues? What type of advance planning strategy could a local public health department use to identify the contributing factors to this public health emergency? What approaches could a local public health department use to deliver comprehensive public health prevention, intervention, and risk communication measures before, during, and after such an outbreak?

What are the potential environmental impacts of a dirty bomb? What can be done to prepare for and respond to such impacts? How would local, state, and federal public health and partner emergency response agencies work together in this scenario? What steps would be taken to distinguish a dirty bomb vs. from another type of explosion? What steps would be taken to evacuate, contain, and decontaminate the affected area? Would evacuation involve all of Anywhere County? Who would take the lead in communicating timely, accurate information to the public on radiation terror before, during, and after this event? What would the crisis- and consequence-phase mental health service responses be to an attack on Anytown by a “dirty bomb”? What steps, if any, could have prevented this attack from occurring or could have reduced the number of deaths and injuries?

As an integral component of homeland security in the post–11 September environment, the public health infrastructure faces new and significant challenges of recognizing and responding to a broad range of intentional and naturally occurring large-scale threats. Furthermore, since the anthrax attacks of 2001, the concept of public health emergency preparedness in the United States has evolved and expanded from a bioterrorism focus to an all-hazards readiness and response model. The all-hazards approach means that the infrastructure and skill sets used to prepare for and respond to a bioterrorism event can also be applied to a wide spectrum of current and emerging natural and intentional threats to the public’s health, ranging from an infectious disease outbreak to a weather-related disaster.

Effective public health emergency preparedness and response requires appropriate preevent, event (crisis phase), and postevent (consequence phase) activities. In the context of emergency readiness, preevent activities include risk assessment, risk communication, and primary prevention efforts (e.g., preevent vaccination). Event-phase public health activities involve crisis risk communication and community-based medical interventions such as postexposure prophylaxis and treatment, crisis mental health counseling, and isolation/quarantine measures. Postevent activities involve consequence-phase disaster mitigation and treatment of longer-term physical and mental health sequelae, along with ongoing risk communication and recovery efforts.

Table 2 presents a conceptual overview of public health emergency preparedness and response activities and competencies and how they might be illustrated using the Haddon matrix. Items with asterisks on Table 2 are CDC-adopted emergency preparedness competencies for all public health workers developed by the Columbia University School of Nursing Center for Health Policy (2002). This high-level view of the issues faced by those preparing for emergencies demonstrates the multidimensional flexibility of the Haddon matrix.

Each phase of a public health emergency presents a unique set of demands on health departments in their readiness and response efforts. Allocating resources for these phases is a significant challenge in the face of competing public health priorities and resource demands. These preevent/event/postevent phase challenges and the organizational flexibility requirements of an all-hazards response model can quickly become overwhelming for public health departments.

By breaking a larger problem into smaller, more manageable components, the Haddon matrix provides a practical, efficient decision-making and planning tool that health department leaders can use to better understand current and emerging threats, perform vulnerability assessments, prioritize and allocate readiness and response resources, and maintain institutional agility in responding to an array of public health emergencies.

Health department leaders can use the Haddon matrix as a planning instrument to dissect the required preparedness and response requirements for any public health emergency scenario, and then strategize to meet these requirements using a “divide and conquer” approach. Once the Haddon matrix has been filled in for a given type of emergency, the cells of the completed matrix comprise specific preevent, event, and postevent task-oriented items that leaders can assign to appropriate staff to optimize their agency’s readiness and response. Some of these items within the completed Haddon matrix may be more responsive than others to public health prevention and intervention, or may represent more pressing needs for a given community; this allows health department leaders to prioritize these assigned tasks based on the health department’s unique demands and resources.

The Haddon matrix can also serve as a helpful after-action evaluation tool to assess a health department’s performance in achieving the goals of a preparedness exercise, or in responding effectively to a real-life event. In this context, the tasks within each cell become items for performance evaluation that can contribute to an effective, comprehensive after-action report.

A view of readiness challenges through the lens of the Haddon matrix also promotes efficient use of public health resources, because the matrix can reveal strategies that allow multiple issues to be addressed by one solution. For example, the logistics of trying to anticipate every possible source of attack or emergency are staggering and impractical. The establishment of an effective incident command system and flexible emergency operations plan within a health department facilitates a more effective response regardless of the emergency. Through the use of the Haddon matrix, it becomes much more likely that public health departments will be able to maximize their readiness efforts, because policies and procedures that are identified as clearly beneficial in multiple scenarios can be developed ahead of less generalizable efforts.

The Haddon matrix also promotes efficient resource allocation by focusing on appropriate phase responses. Because the matrix requires the user to follow issues across all of the phases of an event, problems that seem insurmountable during one phase might have ready solutions in a different phase. For example, the logistics of adequately sheltering a population upon the release of an infectious disease become much more manageable with a “preevent” educated population that understands the concepts of sheltering in place, emergency supply kits, and resources for additional trustworthy information.

The model shows considerable flexibility as a tool to address threats—both intentional and unintentional—that face public health departments in their efforts to enhance public health readiness and response. From SARS to dirty bombs, the Haddon matrix reveals itself as a useful public health readiness tool for tackling difficult public health emergencies.

SARS is an example of a naturally occurring public health epidemic that can be better understood and addressed via the Haddon matrix. From diagnosis, to treatment, to infection control, to risk communication, SARS is an infectious disease that exacts significant stress on multiple facets of the public health infrastructure (Affonso et al. 2004; Gostin et al. 2003).

A myriad of public health response issues surround a SARS outbreak. Table 3 shows an example of the Haddon matrix as applied to one such issue: SARS hospital infection control. This SARS model of the Haddon matrix views infectious disease as a form of injury affecting the population on a broad scale. The model allows its users to better understand the multidimensional nature of the epidemic and to identify targets for prevention, mitigation, and intervention. By identifying targeted points of intervention (noted with asterisks in Table 3), we can discover potential measures to successfully mitigate the public health threat before, during, and after a SARS event.

Table 3 illustrates some of the hospital infection control factors that should be considered in the event of an emerging infectious disease outbreak such as SARS (Loutfy et al. 2004; Svoboda et al. 2004). Lessons on public health readiness are often learned painfully after large crises, as was the case during the SARS outbreak of 2003 (Campbell 2004; Hearne et al. 2004). Using the Haddon matrix before an event occurs allows us to consider the interplay of variables that might otherwise have been missed (and were missed during the actual events associated with the SARS outbreak). For example, in the pre-event phase under physical environment, the Haddon matrix reveals the importance of addressing the need for adequate personal protective equipment; this may seem obvious enough in hindsight, but this issue received insufficient attention before the SARS outbreaks in 2003 (Campbell 2004; Reznikovich and Balicer 2004).

Equally important, the model is flexible enough to allow for big picture analysis of a situation, or a more focused analysis of the smallest units of study, including individuals. As a tool to understand, prepare for, and respond to SARS, the Haddon matrix thus reveals itself as a highly adaptable model.

From a public health emergency readiness standpoint, the Haddon matrix’s adaptability also extends to environmental impacts of nonbiologic origin. Radiation terror preparedness, for example, is a significant challenge in the emerging all-hazards public health readiness framework, because the physical and mental health impacts of radiation terror on an affected area can be profound and long lasting.

Radiologic dispersal devices (“dirty bombs”) are examples of radiation terror that present a challenge for homeland security because of their simplicity and relative ease of acquisition. Dirty bombs are conventional explosives bundled with ionized radioactive sources, and remain a front-line terrorism preparedness concern in the post-11 September era (Zimmerman and Loeb 2004).

Applying the Haddon matrix to the threat of a dirty bomb illustrates the value of this injury prevention model as a public health readiness and response tool, even when focusing exclusively on environmental issues. Table 4 shows how the Haddon matrix can be applied to address environmental health issues related to dirty bombs. Although the human, agent, physical, and social factors are numerous, a closer look reveals a more specific set of points for targeting environmental assessment and intervention (Table 4).

Like the Haddon matrix for SARS in Table 3, the Haddon matrix for dirty bombs in Table 4 reveals the host, social environmental/organizational culture, and selected physical environmental dimensions as major points of impact for public health assessment and intervention (noted with asterisks). Hazardous materials (Hazmat) and other first-responder agency personnel would comprise the front lines at the scene of a dirty bomb event, rather than health department workers. Nonetheless, a comparison between the dirty bomb and SARS Haddon matrix examples shows marked similarities in the importance of risk communication, mental health support, resource use, surge capacity, and effective surveillance as points of public health impact, consistent with an all-hazards readiness and response framework.

Table 4 reveals that from an environmental perspective, modifiable public health “impact” opportunities for dirty bomb preparedness and response involve mainly organizational culture/social environment factors, as well as a few host and physical environment factors. The legal and regulatory aspects of environmental remediation after a dirty bomb are critical public health issues with significant economic implications (Elcock et al. 2004); these are also reflected in Table 4 as “impact” opportunities on the Haddon matrix.

Collectively, these modifiable host, physical environment, and social environment/organizational culture factors represent targets for streamlining readiness and response activities; addressing the safety, risk perception, and mental health needs of first responders and Hazmat personnel; and managing the financial resource and response issues of a dirty bomb—all of which are critical pieces in dealing with the environmental impacts of a dirty bomb.