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The nature of the disaster is widely variable and can include a terrorist attack, infectious pandemic, mass transit accidents, or natural disaster and all of them can exhaust regional or national critical care systems. As highlighted by the 2007 US Homeland Security Task Force,11 the scenarios which can generate massive amounts of critically ill victims are broadly divided into 3 general categories: terrorist attacks, epidemic disease, and natural disaster.

  • Natural disasters arise from forces of nature and include earthquakes, volcanic eruptions, hurricanes, floods, fire, and tornadoes.

  • Infectious disasters can be classified as epidemic or pandemic.

  • Manmade disasters are due to identifiable human causes and may be further classified as complex emergencies (eg, wars, terrorist attacks) and technologic disasters (eg, industrial accidents, explosions from hazardous material).

Regardless of the type of classification used to categorize disasters, certain unique features are associated with each type of disaster. It is important to understand the common effects of different natural and manmade disasters to predict their impact and plan effectively.15

Natural Disasters


Earthquakes are common and even predictably frequent especially in many earthquake prone areas of the world and result in significant mortality.11 Availability of health care providers well trained in basic and advanced trauma and life support and the architectural design and build quality of the stricken area’s housing and public facilities are 2 major determinants of outcomes for earthquake victims. Earthquakes also commonly result in damage to health infrastructures and water systems and create disruptions to communication and transportation networks.11

Volcanic Eruptions

Different types of eruptive events occur, including pyroclastic explosions, hot ash releases, lava flows, gas emissions, and glowing avalanches (gas and ash releases). Although lava flows tend not to result in high casualties, the “composite” type of volcano is associated with a more violent eruption which is associated with air shock waves, rock projectiles (some with high thermal energy), release of noxious gases, pyroclastic flows, and mud flows (lahars). The morbidity and mortality are related to respiratory-related syndromes and conjunctival and corneal injury, topical irritation of skin and other mucosal surfaces.15

Hurricanes, Cyclones, and Typhoons

These are large rotating weather systems that form seasonally over tropical oceans. They are among the most destructive natural phenomena. Many complications are the result of widespread flooding and most hurricane-related deaths occur from storm surge-related drowning. The most common injuries include lacerations, blunt trauma, and puncture wounds. Late morbidity can be due to postdisaster cleanup accidents (eg, electrocution), dehydration, wound infection, and outbreaks of communicable disease.11


There are 3 major types of floods: flash floods (caused by heavy rain and dam failures), coastal floods, and river floods. Together, they are the most common type of disasters and account for at least half of all disaster-related deaths. The primary causes of death are drowning, hypothermia and injury due to floating debris. The impact on the health infrastructures and lifeline systems can be massive and may result in food shortages. Interruption of basic public services (eg, sanitation, drinking water, electricity) may result in outbreaks of communicable disease. Another concern is the increase in both vector-borne diseases and displacement of wildlife.15


They are defined as downslope transport of soil and rock resulting from natural phenomena or manmade actions and are more widespread than any other geologic event. Landslides cause high mortality but relatively few injuries. Trauma and suffocation by entrapment are common. Pending an assessment needs can be anticipated, such as search and rescue, mass casualty management, and emergency shelter for the homeless.15

Other Natural Disasters

Tornadoes occur most commonly in the North American Midwest. They cause widespread destruction of community infrastructure. Injuries most commonly seen are complex contaminated soft-tissue injury, fractures, head injury, and blunt trauma to the chest and abdomen.

Infectious Disasters

Pandemic Respiratory Infections

Pandemic H1N1 2009 was caused by a new strain of influenza A virus that within weeks spread worldwide through human-to-human transmission. During the first month of the emergency, the CDC’s Strategic National Stockpile released 25% of the supplies in the stockpile for the treatment and protection from influenza.6 At the third month the World Health Organization (WHO) declared the 2009 H1N1 influenza a global pandemic, generating the first influenza pandemic of the 21st century. The initial data show that about 8% of H1N1 patients were hospitalized (23 per 100,000 population); 6.5% to 25% of these required being in the ICU (28.7 per million inhabitants) for a median of 7 to 12 days, with a peak bed occupancy of 6.3 to 10.6 per million inhabitants; 65% to 97% of ICU patients required mechanical ventilation, with median ventilator duration in survivors of 7 to 15 days; 5% to 22% required renal replacement therapy; and 28-day ICU mortality was 14% to 40%.6

Judicious planning and adoption of protocols for surge capacity and infrastructure considerations are necessary to optimize outcomes during a pandemic.16,17 Safe practices and respiratory equipment are needed to minimize aerosol generation when caring for patients with influenza. These measures include hand-washing, gloves and gowns, and the use of N95 mask.16,17

Manmade Disasters

Transportation Disasters

Transportation accidents can produce injuries and death similar to those seen in major natural disasters. Some of the largest civilian disasters in North America have been related to transportation of hazardous materials, but more commonly they are related to motor vehicle accidents, railway accidents, airplane crashes, and shipwrecks. They cause a wide range of injuries including multiple trauma, fractures, burns, chemical injuries, hypothermia, dehydration, asphyxiation, and CO inhalation.15

Weapons of Mass Destruction

Weapons of mass destructions (WMDs) are those nuclear, biological, chemical, incendiary, or conventional explosive agents that pose a potential threat to health, safety, food supply, property, or the environment. Since the terrorist attacks in September 2001 and subsequent intentional release of anthrax spores in the United States, there is growing concern around the world about the possible threat of chemical, biological, or nuclear weapons used against a civilian population. In response to a WMD incident, healthcare personnel should be prepared to manage casualties in an environment of panic, fear, and paranoia.4 Because most attacks occur without warning, the local healthcare system will be the first and most critical interface for detection, notification, rapid diagnosis, and treatment.11

Biological Weapons

Biological weapons can be either pathogens (disease-causing organisms such as viruses or bacteria) or toxins (poisons of biological origin). Compared with other WMDs, biological weapons are characterized by ease of accessibility and dissemination, difficulty in detection because of their slow onset of action, and their ability to cause widespread panic through the fear of contagion.11,18 Based on these characteristics they require special action for public health preparedness. In the event of a suspected bioterrorist attack, the CDC has issued protocols for early notification of local and state public health department agencies.

Chemical Weapons

Chemical incidents are events that threaten to or do expose responders and members of the public to a chemical hazard. Agents commonly used as chemical weapons are also used in industrial processes. These agents, however, pose serious problems for emergency care providers because of their potential to cause a large number of casualties rapidly and their potential for secondary contamination. Any emergency medical or public health response to a major incident involving a chemical warfare agent will require coordination among local, state, and federal organizations. First responders should be aware of access to specialized local and federal response teams, basic triage and demarcation of the contaminated area, use of handheld devices for agent detection and identification, use of personal protective equipment, and knowledge of appropriate medical treatment and antidotes.11

Nuclear Weapons and Radiation Accidents

A variety of terrorist applications of radiation exist that could produce varying degrees of damage to public infrastructure and operations, human casualties and illnesses, and most importantly, fear. Approximately 50% of the energy released from a nuclear bomb is due to the blast and shock waves, giving a majority of the survivors blast-related injuries as well as creating extensive infrastructure damage. About 35% of the energy released is thermal radiation (in orders of tens of millions of degrees), giving rise to high-degree skin lesions. However, the most likely terrorist threat using radiation is the so called “dirty bomb” in which some type of radioactive material is added to a conventional explosive bomb. Among experts in this field it is thought such a bomb would most likely involve the use of more easily accessible but less dangerous forms of radioactive material; thus the likelihood of mass casualties with acute radiation poisoning at this point is not high.11

Hazardous Materials Disasters

A hazardous material is a substance potentially toxic to the environment or living organisms. Full-scale disasters from hazardous materials disasters (HazMat) are relatively rare, but isolated incidents are among the most common in the community and are not limited to chemicals but can include various biological and radiologic materials as well. Knowledge of the types of industries present in the community would be helpful in developing a potential plan to deal with likely HazMat situations. Injuries secondary to release of hazardous materials can present as chemical burns, inhalational injury, and a variety of systemic injuries.11

Armed Conflict

Armed conflict continues to be the most preventable and destructive of manmade disasters. Specific healthcare issues during these conflicts include trauma from blast injuries and projectiles, crush-related injuries, communicable diseases due to the breakdown of public infrastructure, mass displacement of populations, burns, and radiation-related injury.15

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