Disasters: Introduction and State of the Art

Fifteen years have passed since the last update on this topic was published in Epidemiologic Reviews (1) and 24 years since the first (2). In the intervening years, disaster prevention, mitigation, and preparedness have evolved in important ways (3). Clearly, it was time to update the last review. Fifteen years ago, disaster management was simply left to a few dedicated professionals. Roles were clear: Rescue workers rushed to help victims, and certain agencies stepped in to provide temporary shelter and food. Usually within weeks after the disaster's impact, most people forgot about the disaster—until the next one came to wreak new destruction. Unfortunately, disasters throughout the world, such as the series of four destructive hurricanes that struck the southeast coast of the United States from August to September of 2004 (4) and the tsunami disaster in December 2004, have provided ample opportunities to test the policies and recommendations set out in the late 1980s. At least 80 percent of the population growth in the 1990s has occurred in towns and cities. According to the United Nations, in the year 2005, one half of the world's population will live in urban areas, crowded onto just 3 percent of the earth's land. This is an alarming increase in population density. Problems inherent in such rapid growth are especially unwieldy in developing countries; 17 of the 20 largest cities are now in developing countries compared with seven of 20 in 1950. By 2025, 80 percent of the world's population will reside in developing countries. One of every two large cities in the developing world is vulnerable to natural disasters such as floods, severe storms, and earthquakes (3). Fortunately, over the past decade, the public health approach to disasters has changed significantly. Today, the management of humanitarian assistance involves many more and different players, and disaster management is recognized as a significant priority of the public health system. Today, prevention, mitigation, and preparedness are part of the vocabulary of public health officials in national and international organizations and, more importantly, they are used to advance the cause of reducing mortality and morbidity from disasters (5). Epidemiology, as the applied instrument of public health interventions, can provide much needed information on which a rational, effective, and flexible policy for the management of disasters can be based. In particular, epidemiology provides the tools for rapid and effective problem solving during public health emergencies, such as natural and technologic disasters and emergencies from terrorism. After sudden-impact disasters, time constraints and disruption of an area's infrastructure have frequently made it necessary to conduct rapid assessment surveys using nonprobability sampling methods. These methods may produce biased results because they are often based on purposive, convenience, or haphazard selection of subjects for interview (6). In the last 15 years, investigators demonstrated the use of a modified cluster-sampling method to perform a rapid needs assessment after hurricanes (7, 8). In the first survey conducted 3 days after Hurricane Andrew struck south Florida in August 1992, clusters were systematically selected from a heavily damaged area by using a grid that had been overlaid on aerial photographs. Survey teams interviewed seven occupied households in consecutive order in each selected cluster. Results were available within 24 hours of beginning the survey. Surveys of the same heavily damaged area and of a less severely affected area were conducted 7 and 10 days later, respectively. Initial survey workers found few households with injured residents, but a large proportion of households were without telephones or electricity. The workers' findings convinced disaster relief workers to focus on providing primary care and preventive services to residents rather than to divert resources in order to establish unnecessary mass-casualty trauma services. The cluster-survey method used in this rapid assessment was modified from methods developed by the World Health Organization's Expanded Programme on Immunization to assess vaccine coverage. Although cluster surveys have been used in refugee settings to assess nutritional and health status, this activity represented the first use of the Expanded Programme on Immunization survey method to obtain population-based data after a sudden-impact natural disaster. Although cluster-survey techniques hold promise for providing information rapidly after a disaster, in certain settings these techniques may be less applicable. For example, epidemiologists who used a cluster-survey technique after the January 1994 earthquake in Northridge, California, found that the technique needed modification. Unlike the damage from hurricanes, which is generally uniform over a large geographic area and thus can support the use of cluster sampling, earthquake-related damage varies considerably, with some areas experiencing little destruction and others experiencing heavy destruction. The extent of damage after earthquakes depends on local soil conditions, the distance and rate of ground-shaking attenuation from the epicenter, and the quality of building construction. Therefore, using a cluster-sampling approach to assess damages after an earthquake may cause health authorities to miss seriously affected areas and, thus, to underestimate overall damages (9). Results of epidemiologic studies of disasters have not only led to the scientific measurement and description of disaster-associated health effects but also been used to identify groups in the population at particular risk for adverse health events, to help emergency managers match resources to needs, to monitor the effectiveness of relief efforts, to improve contingency planning, and to formulate recommendations for decreasing the adverse public health consequences of future disasters (3). Unfortunately, it is assumed by many that all disaster research has been and will be based upon “scientific evidence.” Evidence consists of data upon which a judgment or conclusion may be based. Evidence must be “valid.” Evidence-based disaster medicine, therefore, supposedly is based upon facts. For example, disaster planning is only as good as the assumptions on which it is based. However, these assumptions are often based on conventional wisdom and stereotypes rather than on systematically collected evidence. While these assumptions may be logical, what is logical is not always what is true (10). For example, it is often assumed that disasters trigger widespread panic and leave stricken populations helpless and dependent on government authorities and rescue and relief organizations for strong leadership and assistance. Disaster planning often focuses on what these agencies can do for the public with the view that the public can do little for itself. Planners may be unaware that there exists a large body of evidence on disaster responses that has been collected over several decades by rapid-response field teams from scientific institutions specializing in disaster research. This evidence shows that panic is extremely rare in disasters and that members of the public in the impact area will take the initiative to help themselves and others. Most postearthquake or post-building collapse search and rescue, for example, is carried out not by police, firefighters, and formally trained rescue teams but rather by the survivors themselves (family members, neighbors, coworkers, friends, and those who just happen to be in the area) (11). To the lay public, the best emergency care is seen as transport as quickly as possible to the closest hospital. If ambulances are not immediately available in sufficient numbers, the survivors will use whatever means of transport that is expedient to accomplish that objective (e.g., private car, bus, taxi, or even on foot). During the September 11, 2001, World Trade Center attack, for example, only 6.7 percent of the casualties were transported by ambulance. As a result, in most disasters the closest hospitals receive most of the casualties, while those slightly farther away wait for casualties that never arrive. Furthermore, field triage, first aid, and decontamination stations are often bypassed because those transporting victims are unaware of their existence or location, or because they believe that better care is available at hospitals. This all happens very quickly, with hospitals usually receiving no warning that a disaster has even occurred and, most importantly, that they will be inundated with casualties beginning to arrive within a few minutes. Officials who are unaware of this evidence may inadvertently create dysfunctional plans. For example, they may designate one hospital to receive casualties contaminated by hazardous substances. They may assume that the fire department will decontaminate casualties at the scene, or that hospital staff will have advanced notice so they can don chemical protective suits and set up decontamination equipment before patients arrive. Evidence collected by epidemiologists is also useful for planning. For example, the primary focus for disaster medical planning has traditionally been on hospital treatment of the critically injured. However, evidence from epidemiologic studies indicates that most disaster injuries are relatively minor and could easily be treated in urgent care centers, private physicians' offices, outpatient surgery centers, and clinics—sparing hospitals for the more serious cases. Additional evidence suggests that many postdisaster visits to hospital emergency departments are for medical conditions other than injuries (10). In some cases, these patients are elderly people who have lost access to their routine sources of medical care (e.g., pharmacies, private doctors, home health care). Yet, there seems to be little planning to ensure that these sources of medical care can survive, function, or expand capacity in disasters (4). Evaluation of the medical and public health responses to disasters is one of the principal responsibilities of epidemiologists with an eye toward progressive improvement in the ability of the health system to respond more effectively and efficiently to disasters (2). Such responses must be evaluated from the perspective of their outcomes and to what extent these interventions benefited victims of the disaster, especially relative to the goals that were expected by such planned responses. Epidemiologists have used a great variety of data collection methods and strategies to study the postdisaster health effects of major disasters involving acute events, such as earthquakes and tropical cyclones. Primarily using descriptive epidemiology, they have collected large amounts of epidemiologic data through case studies of new and previous disasters. However, interventions also may be evaluated with regard to prevention or mitigation of the effect of an event. Such evaluations often are difficult, as their success is assessed by the fact that nothing happened that could have happened. Identification of risk factors for death or injury will require a more sophisticated, analytical approach. Such analytical studies have usually been of a case-control design. For example, why did some people die while their neighbors, family members, or others survived? Isolated case studies of the relation between death or injuries and the type of traditional housing structures have provided clear indications regarding simple measures to be implemented in order to reduce human losses. Such analyses following disasters have yielded new information that has altered traditional thinking about the prevention of disaster-related mortality. Results of epidemiologic research on disasters have formed the scientific basis for increasingly effective prevention and intervention strategies to decrease mortality in several disaster situations. For example, epidemiologic studies of tornadoes have resulted in changes in local housing and land-use regulations regarding the danger of mobile homes and have formed the basis of National Weather Service safety guidelines issued to citizens in tornado-prone parts of the country (12). Results of epidemiologic investigations of a wide spectrum of adverse medical and health consequences of disasters have allowed us to target specific interventions to prevent specific disaster-related health effects (e.g., improved warning and evacuation before flash floods and tropical cyclones (13), the identification of effective safety actions that building occupants should take during earthquakes (14), and the development of measures to avoid clean-up injuries following hurricanes (15)), to measure the effectiveness of disaster prevention and preparedness programs, and to help local communities develop better emergency preparedness and mitigation programs. More analytical studies such as these are needed to test conventional warnings and public safety advisories (5). Despite the existence of useful, systematically collected evidence from hundreds of disasters, this body of knowledge can quickly become out-of-date (1, 2). This is because of changes in disaster threats (e.g., pandemic influenza, suicide terrorism, specific targeting of medical personnel in war zones) and in the health-care system (advances in emergency medical service systems, emergency department overcrowding, nursing shortages, closures of trauma centers). In addition, there still exist critical data gaps in how the health-care system deals with disasters. An example is the lack of systematically collected data on the medical and public health response to releases of hazardous chemicals. Furthermore, we lack an effective, nationally institutionalized process of knowledge transfer for gathering and disseminating lessons learned from health and medical responses to disasters from researchers to first responders. Fifteen years ago, the term “complex humanitarian disasters” was not commonly used. The focus of attention was usually the plight of refugees fleeing conflicts related to the tensions between the two superpowers, the Soviet Union and the United States. Much has changed in the intervening years. First, the geopolitical context has altered dramatically, with an initial increase in the intensity and scope of Cold War-related conflicts in the 1980s followed by the collapse of the Soviet Union and the subsequent “epidemic” of ethnic and religious conflicts. Second, the public health impact of armed conflicts on civilian populations has significantly worsened, especially during the years since the end of the Cold War. Third, on a more positive note, there has been a steady increase in technical publications in the form of journal articles, books, and manuals documenting public health outcomes and proposing more effective responses to conflict-associated population emergencies. The term complex humanitarian disaster reflects the multicausal nature and complicated response mechanisms of recent emergencies. In of their public health impact, complex humanitarian disasters may be as acute large by a of generally or often by and population and in significant The public health impact of complex disasters in the 1990s has been The and have published on emergencies in and and One useful that following the emergency the different to the collection of public health information agencies years later, refugees the of there was a of and of methods the agencies This was in a by 24 epidemiologists from the of World Health United for for and without the and the have been made during the past in the the international to the health and consequences of complex emergencies. The public health and response to of acute has especially in for severely have because of better and focus is on the major of death in acute and and often and even In emergencies in human is also an important cause of morbidity and mortality. and a more of organizations and United agencies are to and morbidity and mortality in complex emergencies While of the public health of refugees and the of and response mechanisms to emergencies significantly more the focus of assistance in the and 1980s was on refugees who had to armed in the 1990s it was often necessary to provide assistance to still in the of the or within their countries. in the of and the had and effects on the health of local civilian populations Today, complex emergencies are humanitarian that not of have become the target of of of have been in urban and public have been and medical services have have been armed and have to be the most and of The of humanitarian assistance in these settings has extremely and The of the is no a of or even with of staff from the of the targeting and of United and humanitarian relief workers have now become an of such all the death of United to on August in 1992, has often become for the of and support to international relief In without such assistance in and the recent tsunami disaster in relief have to a As could be the of the 1990s much and to the traditional humanitarian relief government and in the of the in complex emergencies. in these organizations such as the United (e.g., World Health United United for the of the and the of have overall not leadership and this was to be for the thus of relief However, since the those of the United have their in humanitarian such as providing field programs, and Despite the humanitarian for such many relief organizations believe that this to the danger to their field staff by the between civilian and and with the This a major in the planning, and of the health infrastructure in following the end of major in One of World in on the of medical relief agencies as and is the of in the and of armed in a of and While we a of the new world relief agencies and the who up their field teams will to on the in an September 11, 2001, the United States the in As the to with this it a of in the form of a should be no by now that the of has left an on the world as we all all and the of all countries. Unfortunately, a disaster by the of be very different from other natural or technologic disasters, conventional or even with other of destruction (e.g., or The initial to a disaster will most and health hospital members of the outpatient medical and a wide of personnel in the public health system and not traditional first such as police, rescue, and services. Expanded public health warning and response and health and are critical for an effective response to the focus of such public health preparedness resources and at the and local is that of the nature of and response to future and natural such as pandemic influenza, and the international of severe acute also will over This is a in an of and of is critical that public health authorities the communities they and the with the that to in future will take time to and Furthermore, the public must that medical recommendations about who is at and at one in based on the best available are to new become The that to within a few weeks is especially The is that the effects of a disaster last a time countries many of their and resources in the The of the for assistance is in the of primary health-care systems, and The and needs in the affected areas are more than the needs, but they may be even more of the large relief agencies have capacity for relief and but a from relief to and is a simple a organizations still have much to about from to interventions that the development of a local health-care system In particular, and health will the acute has and the victims often to their means (10). Unfortunately, health and the consequences of disasters have not the attention they in the epidemiologic compared with the research and body of knowledge in the and of populations affected by disasters to or has that these populations may have to with widespread and for years after the disaster relief health-care services in their overall planning for disaster and The health of survivors may also be affected for years, in technologic disasters, such as those involving and For example, the most health with are the effects from to of or by may not many years after and may be by of Epidemiologic study of disasters has during the past 15 years, especially in and and it has an since September 11, of new and scientific for the of in the epidemiology of disasters of research now on the health and medical effects of disasters, the of the World Health of these institutions have also developed that disaster epidemiology, information for disasters and emergency programs, and refugee in a tsunami in the investigations of and chemical and earthquakes in may not have much in but in the of all the epidemiologic approach has As relief agencies have to the of epidemiology in disaster their on the management approach has An approach to data collection in disaster also disaster managers and the variety of that they will during the different of a disaster (3). In with disasters and the of people affected by such on the the of disasters as a public health problem is now This is now by the fact that every of public health in the United States now some opportunities in the public health consequences of disasters from just 10 percent years This of Epidemiologic Reviews consists of several and that will provide with technical of recent disasters and humanitarian 11, The published in this of Epidemiologic Reviews were selected on the basis of their of in the conduct of disaster relief and humanitarian assistance and the of disaster research since the last major of this that through every one of these is all disasters are some exist the health effects of different disasters, can ensure that health and emergency medical relief and resources are