Car Bomb Response

Terrorists today have widely varying mechanisms to spread their destruction; therefore, it is imperative that EMS responders have in-depth knowledge and training in all possible terror scenarios.1 A car bombing or other bombing situation requires discussions, collaboration and training of multiple agencies prior to an incident to minimize casualties.2 In addition to being a disaster area, the blast scene is also a crime scene, and all efforts must be made to maintain the integrity of evidence.

The Car Bomb

Historically, the car bomb has been around for a long time. In 1976, a bomb placed in an embassy limousine killed the Chilean ambassador in Washington, DC. On October 12, 2002, a car bomb synchronized with possibly two other devices exploded in rapid succession, killing 192 people and injuring scores of others at the Indonesian Island Resort in Bali.3 This bombing demonstrates that terrorists have developed methods for synchronizing explosions much like what probably occurred in the recent multiple train explosions in Spain.4 Terrorists are also demonstrating selectivity in their targets. Recently, a Palestine Liberation Organization (PLO) suicide car bomber actually stalked a bus, staying alongside it for miles until the time of detonation.5

The amount and type of explosive needed to make a car bomb varies widely, depending on the bomber’s ultimate goal. If the goal is simply to create immediate destruction of life and property, the terrorist will choose a highly explosive material like C-4, dynamite or Semtex. The Bali attackers used a chlorate combined with other materials to form a plastic-like explosive material that can be molded into various cavities behind a bumper, inside a fender or packed in a trunk.5 On a larger scale, a relatively small rental truck carrying 55-gallon drums full of cheap, ammonium nitrate fertilizer soaked in gasoline was sufficient to destroy the Murrah Federal Building in Oklahoma City in 1995, leaving 168 people dead and many more injured.

In the past, manual or digital clock timers have been used to detonate car bombs, as well as stationary bombs placed in shopping centers and marketplaces. Increasingly, terrorists are using modern technologies like cell phones or portable radios to remotely detonate their devices.2 Communications equipment used by first responders may even be set to trigger an explosion of secondary devices at a scene, greatly compounding the ability of all first responders to operate effectively.

Categories and Properties of Explosives

What are the physical forces at play in an explosive episode? Basically, there are two types of explosive discharges—low velocity and high velocity—based on their speed of combustion. Low-velocity explosives, like gunpowder, are meant to produce a gas output that propels an object (the bullet) for a certain distance. The larger the charge of explosive, the further the object is propelled. High-velocity explosives, on the other hand, are intended to produce a much faster movement of gas and produce an ultra-high-speed wave. It is this ultra-rapid movement of expanding hot gas that crushes structures like walls and destroys buildings and their occupants. This moving front of gas, known as the shockwave, can reach velocities as high as 27,000 feet per second (the speed of sound is about 1,100 feet per second).6 An unconfined shockwave will travel approximately 1,000 feet from the point of detonation within the first second.7 If a car bomb explodes at a mall, for example, the blast will move through the entire mall within the first 2–3 seconds. In addition, since the shockwave is moving from an unconfined space (car parked at the curb) into the confined mall area, the actual velocity of the gas front may increase initially. The temperature of the exploding gas ball will set fire to a variety of combustible materials in its path. This is further complicated by the fact that the hot gas cloud can propel ignited objects away from the initial point of the blast as the cloud continues to expand.6 Thus, subsequent fires can start in other parts of the blast area and serious burn injuries can occur at areas far removed from the primary blast site.

If the purpose of the bombing is to destroy life, the bomb may be loaded with various types of shrapnel (nails, screws, razor blades, etc.) intended to inflict harm. Secondary bombs may be placed around the blast area, and these can take any shape, size or form. Improvised explosive devices (IED) may be inside a book, a knapsack, a box or a briefcase. The only limitation on an IED is the builder’s imagination.5 A bomb with a chemical or biological agent will use a low-velocity explosive designed to deflagrate, or produce a gas output that can propel the active agent throughout the blast area without destroying the active agent itself. The only truly effective military bombs for release of biological agents are those developed by the Russians for release of smallpox. These consist of bomblets, which are released from an aerial biowarhead, then float to earth on parachutes and burst under low explosive discharge to release either liquid or powdered agent.8 In fact, the car bomb itself may simply be a cover or a trigger for the release of an agent from some other type of aerosol-generating device already placed in some location within the mall area.

Responding to a Car-Bombing Scene

EMS personnel arriving at the bombing scene need to establish a secure area for triage and patient management. It is essential to size up the scene and determine the safest place to establish an operating base, realizing that there is always the chance of a secondary explosion, either intentional or simply from some ignitable material in the primary blast area.2 The triage area will need to be established upwind from the primary hot zone. The blast most likely will have put a large quantity of particulates into the air. Depending on the age of the building, these may include: asbestos, lead paint, fiberglass, silica and a variety of other inhalation hazards. If chemical or biological agents are involved, there is the increased threat of continued exposure to these agents. A constant eye must be kept on wind direction. If wind direction changes, the area for performing on-site preliminary medical treatment (bleeding control, airway management, etc.) may need to be relocated rapidly before all victims have been moved to transport vehicles.

Guidelines for predicting safe evacuation distances have been published, including those shown in Table I. “ATF Safety Guidelines for Vehicle Bombs” shows the maximum amount of explosive each vehicle type can hold, the lethal air blast range and, most important, the recommended minimum evacuation distance, defined as the distance beyond which life-threatening injuries are unlikely.9 However, in a biological attack, the agent, particularly of military grade, may be carried on winds that might otherwise not spread larger traditional explosive by-products. If the presence of an agent is unknown, this will present an additional threat to EMS workers performing routine patient care functions.

Biological/Chemical Threats

If a chemical nerve agent like sarin gas (the military’s Agent GB) or Soman (Agent GD) is used in an explosion, there is immediate evidence of poisoning in individuals with advanced stages of respiratory failure, or individuals dead without other apparent major injuries from the blast.10 However, with blister agents like phosgene or mustard gas, symptoms may not become apparent for 2–6 hours after exposure.11 Thus, in addition to dealing with the usual traumatic injuries expected from an explosive event, you may also be faced with victims who, after being treated for minor injuries at the site, may develop subsequent toxic, potentially lethal effects. EMS workers are also at risk for potential exposure to the chemical agent. This may be direct exposure or, in the case of agents like cyanide and phosgene, occur because of off-gassing from victims’ clothing. This may occur at the site, in emergency vehicles or at hospital EDs.11 Nerve agents like sarin are readily adsorbed through the skin and can produce significant exposure through unprotected dermal and mucous membranes. Their reaction is normally rapid and usually fatal.

If the car bomb is a cover for a biological agent release with bacteria like anthrax or tularemia, a viral agent like smallpox or hemorrhagic fever-causing viruses like hantavirus, there will be no immediate signs of illness. Generally, the incubation period for biological agents is between 2–14 days depending on the agent.12 Likewise, if a biological toxin like ricin or botulinum is used as part of the explosive mixture, it will be hours or days before symptoms begin to appear.13,14 This means that first responders may be providing traditional disaster first aid to individuals who are contaminated with biological agents. Exposed individuals treated at the scene or transported to medical facilities have the potential to spread a biological infection well beyond the initial blast scene.

Although unlikely, if the biological agent used in a vehicle explosion is identified, then the Strategic National Stockpile (SNP) prophylactic treatment protocol should be initiated immediately.15 This treatment protocol involves drawing resources from the national repository for pharmaceuticals, vaccines and other medical materials established to meet such emergencies and procedures for their administration. The program is managed jointly by the Department of Homeland Security (DHS) and the Department of Health and Human Services (DHHS) and is located at the Centers for Disease Control and Prevention in Atlanta, GA.

Unless there is some evidence of a chemical or biological agent release at a scene, there is almost no way of knowing such an event has occurred. Discovery of spraying devices, suspicious aerosols or droplets of liquid would provide an indication of such a release; however, in the aftermath of an explosion, with the debris, dust and fire, finding such evidence immediately is unlikely.

For this reason, a primary concern for EMS responders has to be self-protection. Responders need to be part of the solution, not inadvertently become part of the problem. Experience with car and suicide bombers has shown that there is often a secondary bomb set to go off soon after arrival of first responders.4 Be aware of the surroundings and any potential additional threats. In the past, most medical emergencies have required personal protection precautions like gloves and a face shield or mask to protect against bloodborne disease. However, in a terrorist attack with chemical or biological agents, depending on the agent, level of hazard and the task an individual is to perform, personal protective equipment (PPE) required may range from minimal to full body protection.16 Performing routine emergency medical first aid procedures will be hampered by the constraints of full body protective clothing, so it is essential that EMS personnel practice their procedures under simulated attack conditions.

If the agent used is ricin or botulinum toxin, adequate protection would consist of respiratory protection with a full face respirator and latex-free gloves. These toxins do not penetrate the skin, so full body protection would not necessarily be required. However, an attack with a chemical agent like sarin or an infectious agent like plague would require full self-contained breathing apparatus (SCBA), face and eye protection, and a form of protective clothing that would provide a barrier to protect the skin from cutaneous exposure.16

The determination of what is the appropriate level of protective gear for EMS first responders has been debated by government agencies and EMS providers. The EPA/NIOSH/OSHA have jointly developed a classification system that sets general levels of protection.17 PPE will also be determined by the relative area in the disaster scene where EMS personnel are working. The conventional hazmat incident response defines three zones: hot, warm and cold.18 In most cases, EMS responders will not be working in the hot zone, since activity in this area is generally the responsibility of hazmat and firefighter personnel. The hot zone is the primary zone of attack, where the potential for exposure to biological/chemical aerosols or liquids is greatest. This area generally requires Level A PPE with SCBA or SAR (supplied air respirator) equipment, depending on the level of threat presented by the agent present (e.g., nonabsorbed toxins like ricin would require less stringent coverage).

The warm zone is an area adjacent to, and usually upwind of, the hot zone. This is the area where contaminated victims are brought to undergo decontamination in a conventional hazmat incident, and where EMS crews set up to provide medical assistance to the victims. In a biological attack, the nature of the agent will most likely be unknown initially. If an agent is suspected, the type of PPE required in the warm zones depends on type and route of exposure of the suspect agent. If the agent in the warm zone is unknown, i.e., chemical, biological or a combination of both, OSHA regulations currently require Level B PPE for EMS personnel.12 At this level, full respiratory protection is required, but a nonencapsulated suit, or so-called “splash suit,” that is chemically resistant can be worn. This allows EMS workers more flexibility in performing their job than they would have in a cumbersome fully encapsulated suit. The cold zone in classical hazmat incidents is the area free of contamination; however, in a biological attack, patients may still be carrying an infectious disease with the potential to spread it to EMS personnel or others outside the area. Therefore, in our current scenario, if a suspect agent is present, EMS workers should continue to use Level B protection as well. In addition, infected patients would require containment and isolation on transit to and arrival at hospitals. One potential problem that may be encountered after a biological attack is that a hospital may refuse to accept patients with potentially contagious conditions due to lack of proper isolation facilities or hospital policy.

EMS personnel should follow OSHA 1910 Subpart I Guidelines for Personal Protective Equipment, in particular, the standard for Respiratory Protection, 1910.134.19 This section includes mandatory information for personnel using respirators (1910.134, App D), mandatory Fit Testing Procedures (1910.134, App A), mandatory User Seal Procedures (1910.134, App B-1), mandatory Respirator Cleaning Procedures (1910.134, App B-2) and mandatory Medical Evaluation Questionnaire and Examination (1910.134, App C). In addition, on August 4, 2004, OSHA released a final rule revising the standard for fit testing to include an additional protocol requiring that fit testing be performed under three exercise conditions: facing forward (normal test), bending over and head-shaking.20

EMS agencies must become familiar with these regulations, especially the medical and fit test requirements, by taking approved 40-hour OSHA training courses.21

Some handheld detection devices exist to detect the presence of certain chemical or biological agents like ricin toxin; however, these devices should only be used for a preliminary screen.13 A positive result may indicate an agent’s presence, but a negative result cannot rule out its presence until more definitive results are obtained from a certified laboratory. A positive result can give some guidance about the level of PPE to employ.

Vehicle Bombing-Related Injuries

The types and extent of injuries expected at a car bombing scene are not much different from the traumatic injuries that would be expected at any large disaster event.2 Three main categories of injuries described by the American College of Emergency Physicians include:22

• Primary Injuries—caused by the shockwave, which affects hollow organs like lungs, eardrums and the GI tract.
• Secondary Injuries—caused by shrapnel and other types of flying debris.
• Tertiary Injuries—caused when a victim is projected through the air by the blast and eventually returns to earth.

In addition, other injuries will occur in conjunction with an explosive blast. Patients will have all stages of burns, crush injuries and head injuries, and there will be extensive aggravation of preexisting conditions such as acute coronary problems, asthma and high blood pressure.2 As in any disaster situation, there will be panicked victims with breathing problems that must be attended to in the routine manner.23

In an explosion occurring inside a building, you are dealing with injuries resulting from overpressurization of the blast area. Thus, victims closest to the blast site will be more significantly injured than those further removed. However, in our vehicle bomb scenario, the blast site is in an uncontained area (outside the mall) and the blast front is moving inside a building area. While the blast front is losing velocity as it moves forward, it is also compressing the air in front of it in the confined spaces (stores, mall, etc.); thus, overpressurization may be greater in some areas further from the blast site. It is important in this situation to know as exactly as possible the location of patients within the blast site in order to provide appropriate treatment for their injuries. More serious injuries may occur at sites further removed from the primary site than would be normally expected.

References

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17. Chemical and Biological Terrorism, Chapter 3. Committee on R&D Needs for Improving Civilian Medical Response of Chemical & Biological Terrorism Incidents. www.nap.edu/html/terrorism/ch3.html.
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19. OSHA, Respiratory Protection Standard and Enforcement, 29CFR- 1910.134. www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12716.
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