Fortunately, when Mount St. Helens erupted in the USA, few people lived at the base or downwind. In addition, Mount St. Helens was the most studied volcano in history; researchers knew that it was going to erupt, so people were prepared for it. Mount Rainier, which is just north of Mount St.
Helens, is expected to erupt sometime in the next 50 years. Should the winds take the ash and debris north and west, the city of Seattle could be severely affected. The principal cause of death from volcanoes is asphyxia from ash inhalation. Eighteen of the 23 immediate deaths from Mount St. Helens were caused by asphyxia. Other mechanisms of morbidity include scalding from the superheated steam, the release of toxic gases, explosions, lava flows, and earthquakes.
Earthquakes have caused more than 1 million deaths worldwide in the past 20 years. The decreasing number of deaths despite increasing population densities is a testament to our improved engineering safety. The principal cause of earthquake-related deaths is collapse of buildings, which causes crush injuries, hemorrhage and shock, drownings if the earthquake is near a coast, asphyxia from the crush or from heavy dust, hypothermia from being left homeless, and sepsis from wounds.
Rescue efforts are most effective in the first 24 to 48 hours after the earthquake. Most morbidity from earthquakes does not require hospital admission. As with other disasters, the injuries are usually cuts, scrapes, minor fractures, and minor head injuries. Chronic illnesses could also be exacerbated because of the lack of medical or hospital facilities. There are many types of man-made disasters. On an individual basis, planes, trains, and automobiles are principal sources.
Engineering disasters, such as the collapse of the Hyatt Regency skywalk in Kansas City, can kill and injure groups of people. When large numbers of people gather for a concert or a sporting event, mass casualty incidents can occur—when people are crushed, for example. Many papers have been written outlining medical needs for these large events, including the numbers of doctors and nurses needed and the amount of water needed to keep people from becoming hyperthermic or dehydrated in the heat.
I will focus on 2 man-made disasters: hazardous materials and radiation. Health care personnel may see 5 or 6 workers who were exposed to organophosphates in their workplace or large numbers of people exposed because of a release into the community.
Recently, a tanker that was carrying thousands of tons of solvents to make plastics sank in the North Atlantic near England. The sinking of the ship did not affect the community but polluted the water; if the ship was instead a train going through downtown Dallas, the situation would have been much different. In Texas, 3. In essence, the Oklahoma City bombing was a problem with 2 hazardous materials: ammonium nitrate and diesel oil.
Unfortunately, most emergency departments are poorly prepared for hazardous materials disasters. Baylor University Medical Center's level 1 trauma center has one decontamination room—a negative pressure room, which has tile floors, a hose for rinsing people off, and a tank underneath the floor to trap contaminated water.
Baylor can certainly treat a handful of workers exposed to pesticides but would be hard-pressed to quickly treat a large group exposed in a major industrial accident. Very few institutions have the extra personal protective clothing needed, including respirator suits, and very few have significant experience with hazardous materials.
In my 12 years' experience in emergency medicine, I have seen 2 hazardous materials incidents, neither of which was very serious. Hazardous materials can reach people through inhalation, skin absorption, or ingestion. Among the inhaled toxins are the asphyxiants, such as carbon dioxide, nitrogen, and methane, which displace oxygen. Those who inhale them are unaware of a problem, since these agents cause no irritation and no physical damage.
Respiratory irritants, such as ammonia, phosgene, and chlorine, are more obvious; they cause edema, secretions, and laryngospasms. Systemic toxins, such as carbon monoxide, and hydrocarbons, such as benzene, toluene, and methylchloride, can also be inhaled.
Pesticides are the classic example of toxins absorbed through the skin. However, chemical burns are another mechanism of skin absorption.
These burns require extensive irrigation. Alkaline burns are more severe than acid burns: when acid burns skin or eyes, it sets up a layer of scar tissue in front of the burn, which prevents the acid from penetrating too deeply into the tissues. Alkaline burns, however, actually liquefy the tissues; thus, no layer of scar tissue forms, and the burn can progress much deeper, causing more extensive damage. Getting splashed in the eye with drain cleaner, then, is much worse than getting splashed in the eye with battery acid.
Radioactive disasters are probably the most feared by the public, although historically there have been relatively few victims. Only 5 events worldwide have prompted disaster responses. Nevertheless, a radioactive disaster can have far-reaching consequences. The explosion at Chernobyl left a radioactive cloud that covered half of the earth. The biggest risks come from nuclear reactors and from transportation of radioactive material. Cancer therapy agents, for example, are transported all over the country.
If a truck or train carrying this material were involved in a collision, large numbers of people could be exposed to radiation. Radiation consists of alpha, beta, and gamma particles. Alpha particles are the least penetrating, while beta particles can penetrate skin and gamma particles can easily pass through the human body and be absorbed by the tissues.
All radiation damage is caused by penetration into the body. Geiger counters can detect beta and gamma particles; a special counter is needed for alpha particles.
Three types of contamination with radiation are possible. With external radiation exposure, the person is not radioactive. An example would be receiving an accidentally high dose of radiation through a computed tomography scanner.
With contamination, gas, liquids, or solids are deposited on the body, and decontamination is required before the patient can enter the hospital. The most severe form of contamination is incorporation, in which radioactive atoms are taken up within cells or body structures and cause damage.
Generally, radium and strontium are deposited in the bones and radioactive iodine within the thyroid. Absorption of radiation is measured with the unit Grey: 1 Gy causes nausea and vomiting in 6 to 12 hours; 2 to 3 Gy, nausea and vomiting in a couple of hours.
Absorption of 10 Gy leads to gastrointestinal syndrome with massive bloody diarrhea, which is also usually fatal. Chernobyl was an example of contamination.
The explosion caused radioactive substances to be deposited on people. In addition, the environment was contaminated, leading to contamination of the food chain. Fish died in the lakes, and people died for weeks and months to come. Other large-scale episodes of contamination occurred in Goiania, Brazil, and Juarez, Mexico, where people found cobalt cancer therapy units lying around after the destruction of hospitals and took home the green, glowing balls of cobalt for their children to play with.
Hundreds of people were contaminated, and it took the health care system some time to identify the cause of the multiple cases of nausea, vomiting, and diarrhea being reported.
Blast injuries and crush injuries are common in disasters, and I will address those. In addition, I will address the incidence of infectious diseases following a disaster. Blast injuries are caused by high-energy explosives—TNT and plastic explosives like those used on the USS Cole —plus any of the nuts, bolts, nails, and other materials sometimes added to bombs.
High-energy explosives explode rapidly, in contrast to gun powder, which fizzles. They cause brisance, the shattering of objects. The pressure wave travels faster and harder through water than through air. Following the pressure wave is a negative pressure phase—a longer period of suction formed by the vacuum of the initial wave. If the initial pressure wave didn't break some windows, the negative pressure wave will.
A number of different injuries are caused by the blast wave. The lungs, ears, and gastrointestinal tract are most susceptible. Injuries are caused by 4 mechanisms. The first, spalling or brisance, involves the movement of particles from more to less dense areas, as when liquid in the lungs moves into the gas area of the alveoli and causes pulmonary hemorrhage.
Implosion, which is compression and decompression of gaseous compartments with rupture, can cause rupture of tympanic membranes. With inertia, the human body is thrown against a stationary object. Finally, with pressure differentials, the blast wave drives fluids from their spaces. This is another cause of delayed pulmonary hemorrhage, which can cause death hours or even days after the explosion.
Among secondary injuries are cuts caused by flying glass, shrapnel, and debris that can imbed deeply into tissues. Tertiary injuries occur as people are thrown against hard surfaces. Burns and smoke inhalation are additional related problems. Most blast fatalities are from brain injuries, skull fractures, diffuse lung contusions, and liver lacerations.
Tympanic membrane rupture is a sign of being close to the blast and thus a marker for more serious injuries. Crush injuries occur as people are trapped under collapsed buildings. A major problem of crush injuries is rhabdomyolysis, i. Half of those with severe rhabdomyolysis will go into renal failure, since myoglobin is toxic to the kidneys. The risk of kidney failure increases with delays in fluid therapy.
Most people who survive crush injuries in earthquakes are rescued early; the longer they lie under buildings, the bigger risk they have of dying from rhabdomyolysis. Compartment syndrome is seen with crush injuries as well. A forearm, for instance, has 2 compartments, dorsal and volar. If one of the compartments is crushed and becomes filled with blood, the pressure inside it increases, neurologic and vascular flow to the distal extremity is lost, and eventually that area will undergo necrosis and require amputation.
Treatment for compartment syndrome is an early fasciotomy to release the pressure. Main menu. Territories for mental and substance use disorders. Ellos escuchan. They Hear You. Solr Mobile Search. Share Buttons. Page title Types of Disasters. Natural Disasters Natural disasters are large-scale geological or meteorological events that have the potential to cause loss of life or property. Human-Caused Disasters Examples include industrial accidents, shootings, acts of terrorism, and incidents of mass violence.
Incidents of Mass Violence Other Incidents of Mass Trauma Infectious disease outbreaks, incidents of community unrest, and other types of traumatic events can also bring out strong emotions in people.
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Read more in our latest World Disasters Report. What is a disaster? What are hazards? Natural hazards are naturally occurring physical phenomena. While hazards may be natural and inevitable, disasters are not. Learn about different hazards. Volcanic eruptions.
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