Natural disasters occur when forces of nature damage the environment and manmade structures. If people live in the area, natural disasters can cause a great deal of human suffering. As a result of disasters, people may be injured or killed, or may lose their homes and possessions. The impact is so great that the affected community often must depend on outside help in order to cope with the results (Noji, Gunn and William). Examples of natural forces that can cause widespread human suffering include earthquakes, tornadoes, hurricanes, floods, volcanic eruptions, wilderness fires, and extreme hot or cold temperatures. Between 1975 and 1996, natural disasters worldwide cost 3 million lives and affected at least 800 million others (Noji). In the United States, damage caused by natural hazards costs close to one billion dollars per week.
PUBLIC HEALTH EFFECTS OF NATURAL DISASTERS
The physical force of a disaster can directly cause injury and death to the population, and each type of disaster can result in its own combination of physical injuries. In earthquakes, buildings and the objects inside them can fall, injuring those who live or work there. Floods can result in drowning, and wildfires can cause burns and illness from smoke inhalation. In addition to the direct injury and death caused by the disaster's force, there can be other serious adverse effects on the well being of those living in the area.
The large numbers of people who are suddenly ill or injured can exceed the capacity of the local health care system to care for them. In addition to the burden of increased numbers of patients, the system itself can become a victim of the disaster. Hospitals may be damaged, roads blocked, and personnel may be unable to perform their duties. The loss of these resources occurs at a time when they are most critically needed.
The disaster also can hamper the ability to provide routine, non-emergency health services. Many people may be unable to obtain care and medications for their ongoing health problems. The disruption of these routine services can result in an increase in illness and death in segments of the population that might not have been directly affected by the disaster.
Much has been written about the mental health aspects of natural disasters. The popular images of a community paralyzed by the shock of the disaster, panicking or looting, are unfounded. Actually, people tend to come together following a natural disaster. Survivors offer immediate assistance to those who are injured or trapped in earthquake damaged buildings, help with sandbagging efforts in floods, offer shelter and assistance to those made homeless, and volunteer goods or money to those in need. However, living in a disaster area can be highly stressful. Staying in damaged buildings, relocating to shelters, dealing with the death or injuries of loved ones, as well as the prolonged time and energy involved in recovering from the affects of the disaster can result in feelings of anxiety and depression. While these might be normal responses to stress and unpleasant events, the degree to which a disaster can disrupt daily living may contribute to an increase in these feelings.
ENVIRONMENTAL HEALTH AND POPULATION DISPLACEMENT
Certain disasters can interfere with the functioning of water and sewage systems as well as the provision of gas and electricity. The loss of these everyday services can increase the risk for sickness even in uninjured people. For example, drinking unclean water or eating inadequately stored or prepared food can cause serious intestinal illness.
The most serious consequences of natural disasters are related to mass population displacements. Many people cannot stay in their homes because the buildings are so badly damaged that they are structurally unsafe. Others refuse to stay in otherwise stable buildings because they fear that they might collapse. While this often occurs following violent storms, it is particularly the case after earthquakes, when potentially damaging aftershocks commonly occur. In many cases, those displaced by disasters find shelter in the homes of people they know, while others must go to shelters staffed by disaster relief authorities such as Red Cross/Red Crescent Societies and government agencies.
Placing large numbers of people in crowded shelters poses a risk for additional health problems. It can be difficult to provide so many people with clean drinking water, sufficient waste disposal, and safe, nutritious food. This temporary living situation can also increase the chances for outbreaks of certain diseases. It is important to remember that only those diseases that are found in the affected community during predisaster times pose a danger to displaced populations after a disaster occurs. For example, it would be unlikely for those living in a shelter following a flood in the upper Midwest portion of the United States to experience an outbreak of malaria (as malaria does not exist in that part of the world), but poor sanitary services could contribute to an outbreak of conditions such as infectious diarrhea or some forms of respiratory illness. In addition, an occasional outbreak of more serious illnesses that might occasionally appear in the community during nondisaster times, such as meningitis or measles, would be a more significant health risk in shelters.
When large numbers of people gather in unsheltered settings, such as parks or open fields, there is an even greater risk of illness. This is because these areas often do not have enough sanitary services. Clean drinking water may have to be trucked into the area, and prompt attention must be directed to providing facilities to handle human waste. The ability to receive, safely store, and prepare food is also a concern for the health of the displaced population. Flies, mosquitoes, and rodents that might be carrying diseases that can cause illness in humans add to the risk of living in an unsheltered setting.
NEEDS ASSESSMENTS AND SURVEILLANCE
The impact of a disaster on the public's health poses special problems for public health professionals. They must monitor the health needs of the disaster-affected population and work to ensure that emergency managers take actions to meet those needs. They also need to maintain the everyday public health programs that were in place before the disaster occurred. These challenges can be addressed in several ways.
Rapid assessment surveys can be conducted of those living in areas most impacted by the disaster. Often, aerial views of the disaster area can indicate damage to key facilities (hospitals, utility stations, major roads), residential structures, and the assembly of large numbers of people in unsheltered settings. Teams of public health, engineering, social service, and medical personnel can then go to those areas that appear most damaged and begin a survey of the people living there. The affected area is divided into smaller areas, called clusters. The teams interview a representative sample of seven people from each of thirty different clusters in the high-impact disaster area. Using a standard set of questions, they gather information about the number of injuries, deaths, houses without running water, functioning toilets, electricity, heat, and those with ongoing medical conditions (Malilay). With the information gathered from the assessment surveys, disaster health managers can draw conclusions about which segments of the affected community are at greatest need for emergency efforts. Once the decision is made to direct resources to the most seriously affected areas, another rapid assessment may be performed to determine the effectiveness of those efforts.
Other information about the number and types of injured may be obtained from medical facilities. It is important to distinguish between patients who were injured or made ill as a result of the disaster from those who happened to seek medical attention for conditions not related to the disaster. This requires a working knowledge of the injury and illness patterns that are associated with different natural disasters. Definitions of which types of conditions will be attributed directly to the disaster or its consequences also are needed.
Computer models are being developed that can combine views of buildings, transportation ways (highways, railroads, airports, and harbors), utilities, and medical facilities with local hazards of varying severity. These models, currently being tested for earthquakes, allow emergency managers and health planners to predict the extent of damage and injuries if a hazard occurs in their community. Once these models are refined and validated, they may prove valuable to emergency response and public health planners.
As the global population continues to grow and more people live in hazard-prone areas, there will be an increase in the number and severity of mass population emergencies. Public health personnel have a key role in natural disaster preparation and response. Before a disaster occurs, they need to have systems in place to identify and track diseases. They must also understand the basic health issues of water and food safety, sanitation, and environmental hazards.
Public health practitioners routinely provide comprehensive programs of health education and preventive care that put them in close contact with those living in the community. They can use their professional skills to develop and evaluate programs for community disaster preparedness before a disaster strikes. After the disaster, they have the ability to help assess its affects on the local population. By adapting their knowledge and skills to these large-scale emergencies, public health professionals can have a significant impact on reducing the negative health affects of disasters.
Gunn, S., and William, A. (1990). Multilingual Dictionary of Disaster Medicine and International Relief. London: Kluwer Academic.
Malilay, J.; Flanders, W. D.; and Brogan, D. (1996). "A Modified Cluster-Sampling Method for Post-Disaster Rapid Assessment of Needs." Bulletin of the World Health Organization 74(4):399–405.
Noji, Eric K. (1997). The Public Health Consequences of Disasters. New York: Oxford University Press.
