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30 and docks), increasing contaminant spread and area re- as in transporting first responders and providing emergency quiring decontamination. response supplies. Any transportation modes with large buildings may be considered for use as temporary shelters. In some cases, it may be safer to have members of the pub- Transportation Consequence Minimization lic stay in a protected structure, called shelter-in-place, to avoid exposure to a passing cloud or plume of radioactive The first response in the event of a radiation release that material. contaminates transportation pathways would be to close the affected paths until they can be decontaminated and route contaminated people, vehicles, and associated cargo to iso- 2.4 COMPARISON OF CBR THREATS lation and decontamination areas. For rapid response in the event radiation is detected in association with an explosion, How much CBR agents affect the transportation system emergency response plans may specify an immediate, con- depends on factors such as the specific agent, the amount re- servative radius surrounding the explosion site for evacua- leased, the means of dispersal, and the surrounding infra- tion. These boundaries may be adjusted after conducting a structure and population density. In terms of the potential more complete radiological survey. A difficult and proba- area affected by a single event: bly controversial aspect of determining transportation re- sponse goals will be in establishing the physical boundaries · Chemical releases could quickly affect tens of square of isolation areas. Transportation officials are unlikely to miles. While decontamination of the most persistent of have primary responsibility for these decisions and proba- these agents may take many weeks, other agents may bly will be following instruction from the emergency com- naturally degrade or disperse within hours. mand center (e.g., their state emergency management office · Biological releases could also affect tens of miles, and or agency). if a contagious agent is used, could soon lead to global Roads, in particular, are highly susceptible to radioactive effects. While decontamination of the most persistent of contamination from vehicles that have traveled through an these agents may take many weeks, other agents may area contaminated with radioactive particles, thus the greater naturally degrade or disperse within hours. the potential travel time before traffic re-routing, the greater · Radiological releases such as from a nuclear bomb or the area of contaminated roadway. Successfully routing all major nuclear power plant accident could affect hun- potentially exposed traffic to decontamination areas depends dreds of miles. However, more likely scenarios involve on the time it takes to recognize that radiation has been re- dirty bombs, which could affect up to about a square leased. In the case of delayed detection of a radiation release mile. Decontamination of persistent radioactivity would of particles that may adhere to passing vehicles and vessels, probably take months to years. effort may be needed to identify and decontaminate poten- tially contaminated travelers, vehicles, and cargo after they The amount of a CBR agent needed to inflict a similar have left the area of initial contamination. level of effect per area varies by many orders of magnitude. If radiation contamination issues are realized several hours Table 2-14 compares the estimated minimum amount of a to days after a radiological release, identifying cars and ves- threat agent needed to cause heavy casualties within a sels that have passed through a contaminated area would be square-mile under ideal conditions (i.e., efficient dispersal relatively easy within the rail and aviation system, for which and optimal meteorological conditions). essentially all trips are scheduled by a relatively few organi- In addition to the amount of an agent needed to cause zations. Port logs could identify large vessels that may have harm, other important factors in the use of a given CBR passed through a contaminated area. In contrast, the highway agent from the terrorist perspective are ease of acquisition system has essentially no means for identifying vehicles that may have passed through a contaminated area, with the ex- TABLE 2-14 Estimated Amount of CBR Agents for Heavy ception of trucking industry logs. Mass media requests for Casualties Within a Square-Mile under Ideal Conditions highway travelers who may have been passed through cont- Agent Category Description of Material Grams aminated areas to identify themselves may be the only way Conventional Fuel-air explosives 320 million to identify highway system travelers. Fragmentation cluster bombs 32 million Responses to a radiological event may also involve pop- Chemical Hydrocyanic acid 32 million ulation evacuations, in which case transportation paths Mustard gas 3.2 million may be re-routed to expedite one-way travel. If the people, GB nerve gas (sarin) 800,000 vehicles, and cargo from evacuated areas may be contami- Radiological "Crude" nuclear weapon (in terms of 5,000 fissionable material only) nated, isolation and decontamination stops would be estab- Biological Type A botulinum toxin 80 lished along evacuation routes. Essentially all modes of Anthrax spores 8 transportation may assist in population evacuations, as well (Source: Kupperman and Trent, 1979)
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TABLE 2-15 Comparison of CBR Threats (Short-term a few hours to a few days; Medium-term several days to several weeks; Long-term several months to years) Health Effects Agent Identification Decontamination Potential Effect on Transportation Requirements Event Type Time for How Field Overt Event Covert Event Detection/ Overt Event Covert Event Recognized Sensors Identification Radiological Immediate for Same as overt Short-term broad high doses, Long-term service event but more suspension until know delayed for low Must have Readily Seconds Decontamination suspension until High Persistence people affected limited of spread, long- doses. Treatment sensor available (on-site) likely required. safe levels and more term suspension in can reduce health achieved. serious effects. contaminated areas. effects. Chemical Little to no Short-term Short-term suspension of Immediate to Readily decontamination suspension of service until safe levels Low Persistence hours, temporary Same as overt available except for very service until safe achieved. distress to Symptoms seen event but more large releases. levels achieved. mortality. immediately to Seconds people affected Short-term broad Treatment can hours later (on-site) Medium-term and more suspension until know reduce health Decontamination suspension until High Persistence serious effects. limit of spread, medium effects. likely required. safe levels suspension in achieved. contaminated areas. Biological Short-term broad Medium-term High Persistence, suspension until know Decontamination suspension of Low limit of spread, medium Symptoms Same as overt likely required. service until safe Contagiousness suspension in typically delayed but reduced levels achieved. contaminated areas. for days. treatment Short-term Short-term suspension if Some agents: effectiveness Decontamination suspension of the released agent has not Low Persistence, Effective treatment with delayed Some agents: Symptoms seen may not be needed, operations already lost infectivity. Low if initiated prior to application. Available Minutes days to weeks depends on amount depending on the Contagiousness symptoms. for some (on-site) later if no released. amount and agents stability of agent. Other agents: analysis Other agents: Very broad, Possible very broad, Treatment limited Days for lab Broad, medium- medium-term medium term suspension to supportive care. Same as above identification term service suspension of of services until infected Low Persistence, with outbreaks suspension until service until individuals are isolated High around the infected people are infected and safe levels achieved. Contagiousness country and isolated and safe individuals are world. levels achieved. isolated and safe levels achieved. 31
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32 or manufacture and probability of successful delivery to the terrorist act, but it was used nevertheless. Thus, all credible target. Although radiological and biological agents can af- event types must be given serious consideration and response fect a broader geographic area than chemical agents, ob- planning, regardless of their relative likeliness to occur. taining the most potent forms of chemical agents is gener- The general characteristics of CBR releases are summa- ally easier than for biological and radiological agents. rized in Table 2-15 in terms of health effects, agent identifi- For all agents, effective dispersal is a substantial dif- cation, decontamination requirements, and potential effect ficulty. These difficulties are exemplified in the multiple on transportation. CBR subcategories are delineated based attacks by the Aum Shinrikyo cult in Tokyo first using bio- on the agents' persistence and contagiousness. Persistence logical agents without success and then chemical agents refers to the extent of time a released agent remains a threat with modest success (i.e., diluted chemical and crude, rela- in an open environment; and contagiousness denotes the po- tively poor dispersion). tential to multiply within an infected person and then spread The nature of risk is that while the most likely types of from person to person (i.e., a characteristic unique to biolog- events over an extended time may be predicted, the next sin- ical agents). Both of these factors have a profound influence gle event type cannot be predicted. The 2001 anthrax mail- on the duration of health risks, the scope of human health ef- ings in the United States exemplified this problem in that the fects, and the related duration and magnitude of effects on the agent used was a highly weaponized bacterial strain that is transportation system. very difficult to obtain or produce. Therefore, this specialized For most CBR agents, the magnitude of health effects and form was not among the more likely agents to be used in a related effects on transportation vary greatly for overt and TABLE 2-16 Relative Vulnerabilities of the Transportation System to Releases of Persistent Chemical, Biological, and Radiological Agents (Persistence more than 24 hours to substantially degrade in an open environment) Ability to Retain Difficulty of Ability to Spread Vulnerability Contamination Decontamination Contamination Chem 1 Bio2 Rad 3 Chem 1 Bio2 Rad 3 Chem Bio Rad Transportation Path Road Medium Medium High Medium Medium High Low Low Low Track Medium Medium High Medium Medium High Low Low Low Tarmac Medium Medium High Medium Medium High Low Low Low Air Low Low Low Low Low Low High 4 High 4 High 4 Waterway Low Low Low Low Low Low High 4 High 4 High 4 Indoor or Underground Stations/ Terminals Smooth surfaces High High High Medium Medium High Low Low Low Porous surfaces 5 High High High Medium High High Low Low Low HVAC system Medium Medium Medium Low Low Low High High High Outdoor Stations/ Terminals Smooth surfaces Medium Medium High Low Low Medium Low Low Low 5 Porous surfaces Medium Medium High Medium Medium High Low Low Low Vehicles/ Vessels Smooth surfaces Medium Medium Medium Low Low Medium Low Low Low Porous surfaces 5 High High High High High High High6 Medium Medium HVAC system Medium Medium Medium Low Low Low High High High Contents Crew/ Passengers Medium Medium Medium Medium Medium Medium High6 Medium 7 Medium Cargo/ food/ water High High High Medium Medium High High High High 1 Persistent chemicals include some chemical weapons agents (e.g., mustard agents, VX). Most transported industrial chemicals and many chemical agents are not persistent; thus ability to retain contamination and the difficulty of decontamination is low for many chemicals due to their non-persistence. 2 Persistent biological agents include Anthrax spores, mycotoxins (T2 or yellow rain), and the causative agent of Q- fever, none of which are very contagious. Most other biological agents are not persistent in an open environment, and the ability to retain contamination and the difficulty of decontamination would be relatively low. 3 Most radiological agents are persistent. For those that are not persistent the ability to retain contamination and the difficulty of decontamination would be relatively low. 4 Ability to spread contamination is high, but the contaminant may be relatively quickly diluted below levels of concern. 5 Porous surfaces include corroded metal, cement, rubber, carpet, fabric, etc. 6 Most persistent chemical agents of concern (i.e., mustard and VX) are oily liquids that may adhere to skin, clothing, and other porous surfaces better than solid particle forms of radiological and biological agents. 7 High if the biological agent is contagious (i.e., influenza, pneumonic plague, smallpox, some hemorrhagic fevers).
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33 covert releases (Table 2-15). An overt event is quickly rec- Table 2-16 summarizes the transportation system's rela- ognized because of accompanying signs such as an explo- tive vulnerabilities with respect to the system's ability to re- sion, visible plume, odor, or warning letter. Overt events tain contamination of persistent CBR agents at levels that generally solicit better targeted and measured responses may affect human health, the difficulty of decontamination, from all sectors, including transportation. In contrast, a and the ability to spread these contaminants. covert event is not quickly recognized, which causes delays In enclosed areas (e.g., passenger compartments and build- in agent identification, delivery of emergency response, and ings), the ventilation system may help disperse CBR agents, so implementation of mitigating measures. shutting down these systems is a commonly recommended first- The rapid onset of symptoms from most chemical agents response. In open, outdoor areas, concerns about wind spread of in conjunction with rapid detection technology reduces the contamination may be off set by factors such as the ability of differences in effects between overt and covert chemical re- wind to enhance evaporation of liquid agents and broadly dilute leases. In contrast, firm identification of biological agents vapors and small particles to safe levels and degradation of often takes days after an event is suspected, and in a covert many chemical and biological agents by sunlight. These same event, the development of suspicions of an event may also factors may facilitate decontamination of chemical and biolog- take days to weeks. During such delays, persistent biological ical agents in open environments; however, runoff control of de- agents and infected individuals continue to spread aided by contamination chemicals may be more challenging. the transportation system. In general, porous surfaces have greater ability to retain Rapid detection of radiological agents allows for rela- contamination than smooth surfaces. Porous surfaces such as tively rapid determination (i.e., within hours) of contami- fabric, rubber, and corroded metal have microscopic pits and nated areas (Table 2-15). However, in a covert radiological valleys that may retard natural degradation and hinder de- event with low enough doses of radiation for delayed symp- contamination efforts. toms, the hazard may not be detected for years, or until a After decontamination, the only CBR agents that may be serendipitous measurement of radiation is made. In general, spread further are the subset of biological agents that are con- the speed with which CBR contamination can be identified tagious. For many diseases, the most contagious stages occur affects the duration of broader, shorter-term effects of during the period that infected individuals are obviously sick a CBR release on transportation, and the difficulty of de- and often confined to bed. The transportation system may fa- contamination of the CBR agent largely determines how cilitate the dispersal of infected individuals before conta- long areas of the transportation system may be isolated and gious stages and the possibility of contagious passengers in- restricted. fecting other passengers.