Protecting Buildings From Chemical and Biological Attack

Editor’s note: The following information is based on the proceedings of the “Combating the Vulnerability of Buildings and Infrastructure to Chemical and Biological (C/B) Attack” conference held on January 26, 1999. It was sponsored by The Architectural Engineering Institute, The American Society of Civil Engineers Committee on the Mitigation of the Effects of Terrorism, in cooperation with the U.S. Federal Bureau of Investigation. Norman J. Glover, FASCE, FIStructE, chaired the conference.

The January Conference was inspired by a previous seminar held in late 1998 in Washington, D.C. on Chem/Bio Defense. It was attended by the major govermental agencies charged with the responsibility. This conference made it clear that current thinking on this subject is almost entirely reactive and is exclusively concerned with “after-the-fact” crisis and consequence management. The targeting considered is not necessarily governmental only in nature but deals also with mass transportation and places of public assembly.

Planning deals almost exclusively with response (and recovery) after an attack/incident occurs and concentrates on the medical and public health concerns of identifying the agent, decontaminating, treating casualties, and restoring service.

Secondarily, there was a concern about gathering evidence to identify and apprehend the attacker.

Although there was also a brief comment suggesting vulnerability assessment of potential targets, there was no detailed description or identification of “vulnerabilities” or suggestions for overcoming them other than “securing building structures and systems.”

Little thought seems to be given to getting ahead of the curve and putting a significant effort into protection, prevention, and mitigation; to protect and defend the public by preventing terrorist B/C attacks; or to reduce their effects by making our buildings and infrastructure more protective and resistive to attack.

This attitude is identical with widely held opinions on blast resistance that surfaced in late 1995 after the Alfred P. Murrah Building Bombing in Oklahoma City. Many “experts” said there was no way to defend against bombing without living in caves or fortresses and that these bunker-like buildings would increase the cost of our homes and workplaces by as much as 200 percent while still denying their occupants what we consider livable space.

Since that time, a great deal of study has been focused on the bombing problem so that today we can design new buildings with economy and strength to overcome the destructive consequences of bombing at an estimated cost of between one and six percent of the gross building cost.

In fact, a recent addendum to the Oklahoma City Bombing Study stated that by making none of the fortress-like changes predicted-but by making only some invisible structural changes that would have added $70,000 to the original construction cost-fatalities at the Murrah Building incident could have been reduced by 50 to 85 percent. In 1997 dollars, that would have amounted to saving 140 lives at $500 each.

However, the problem has not been fully solved, and the protective modification of existing buildings remains a daunting problem. A similar approach should work for the C/B problem.


Since the first use of poison gas in World War I, our military services have gained a great deal of experience in protecting their personnel from these weapons. Since the available medical measures, primarily antidotes and vaccines, are not adequately effective, the military response has been concentrated on individual protection with masks, protective garments, and decontamination of affected areas.

However, according to the General Accounting Office, only two U.S. Army divisions during the Gulf War were able to deploy with a full issue of protective equipment. More to the point, the solutions planned for trained, disciplined troops in the battlefield are not apt to be suitable for the general public, which ranges in age from newborn children to bedridden senior citizens.

Nor are terrorists apt to target our military. They will pick unlikely targets like they did in Oklahoma City. Today’s terrorists employ a strategy called “asymmetrical attack,” or, as Civil War General Bedford Forrest describes it, “Hit ’em where they ain’t.” Strike at the weak and unprepared, and shake their faith in society’s ability to protect them.

Often called the “poor man’s nuks,” C/B weapons are perfect for the terrorist’s purpose. They are relatively cheap. Estimates of the weapons’ costs for producing mass casualties per square kilometer (not per casualty) are $1 for biological, $600 for chemical (nerve agent), $800 for nuclear, and $2,000 for conventional.

The know-how for producing and employing C/B weapons is available on the Internet and in mail-order handbooks that cost $15 to $20. Most of the required apparatus and materials-and even toxins-are also available by mail order.

Although military delivery systems are more efficient, delivery of the C/B weapons requires no ballistic or cruise missiles, artillery, or jet bombers. The preferred method of delivery is by aerosol spray. Significant attacks can be carried out with a hairspray or deodorant canister. Larger area attacks are possible with a backpack, truck-mounted pesticide sprayer, crop-dusting plane, or even sightseeing helicopter.

Chemical Agents

Although the aerosol is the preferred method of dispersal for C/B agents, the agents are quite different in their effects. Chemical agents are comparatively immediate in their effects, depending on the specific agent and its concentration. Generally, recovery of a chemical casualty is very time sensitive. Given the problems of identifying the causes of casualty (as opposed to illness), the first responder-at risk, facing personal danger, and having a heavy casualty load-will be faced with a triage situation. Those needing help the most may be least able to benefit from it.

The low level of concentration of the agent used during the Gulf War delayed discovery and caused the lesser (nonfatal) physical effects that came to be identified as the “Gulf War Syndrome.” In such concentrations, the agent may not be detected on equipment, which is calibrated to detect more potent fatal loads. The terrorist may be more interested in creating fear and feelings of dislocation than fatalities; therefore, terrorism should be considered when low concentrations of an agent are detected. A noncritical quantity of radioactive nuclear material dispersed as dust or liquid waste or an explosion involving a small quantity of a conventional explosive might be considered a form of chemical weapon.

Biological Agents

The biological agent presents a different situation. While the effects of most chemical agents are fairly quick and the agents are usually detectable by human senses, the biological agent is not normally discernible or identifiable by the senses. No effects may be evident for days, or even weeks, during which time the victim may travel widely and infect others. The early symptoms may not be identified and, in seeking assistance, the victim may place the health professional, and even the whole local health system, at risk. President Clinton is not the first to characterize this type of agent as “the gift that keeps on giving.”

The ideal defense for a C/B attack would be early intelligence gathering and analysis resulting in police action to prevent the incident and apprehend the potential attacker. This is often not possible for the same reasons that the terrorist bombers have been so elusive. The only available active strategy is that used in mitigating the effects of terrorist bombing. Multidisciplined security and an architectural engineering approach are needed so that the building itself can be used to create a more protective environment to defend against and mitigate the effects of the attack.


A great deal of knowledge is available relative to explosive damage and the blast resistance related to structures. This information will undoubtedly be used in the design of future buildings to reduce the risks associated with terrorist acts. Much less information is available on how to design, build, modify, and use buildings to reduce the consequences of chemical and biological attack.

I propose the following program:

  • Identify the problem. We cannot find the answers until we know the questions. Identify the potential chemical and biological agents, their capabilities, characteristics, and delivery methods.
  • Assess the characteristics of potential targets. Evaluate the buildings and infrastructure, their uses and occupancies, and their vulnerable areas/points/systems; consider how these vulnerabilities can be decreased and these areas best defended.

    The present state of the art does not support continuous, on-line detection. A limited number of chemical agents are identifiable by on-line testing in air-handling systems, but the processing time approaches 60 seconds. In modern high-rise air-conditioned systems, air velocities of 1,000 fpm are common. This means that in the period it takes from first sampling to detection, an 80-story building could be contaminated by toxic gas.

    The state of the art in biological detection is even less effective. Any defensive system in the near term must be continuous and on-line at all times, independent of detectors and alarms.

    • Design the building (and infrastructure) to defend its occupants. The modern glass-and-aluminum building is airtight. Windows are inoperable to allow efficient and economical heating and cooling. It, like the airplane and the subway, is an unnatural environment. Under terrorist C/B attack, it can be a virtual “killing bottle.” However, properly managed, this very vulnerability can be the basis for a defense.

    To this end, a number of methods for mitigating the effects of chemical and biological attack are in research. They include using the building sprinkler systems to mitigate the effects of C/B agents, controlled zoning and venting, and using dampers to cut off the system automatically and force the systems to “fail safe.” A suggestion to “reverse” the air-handling fans is impractical, since most of these fans are centrifugal. Although they can be run backward, they would be only about four to five percent efficient.

    Among the elements of buildings that could be designed or modified to mitigate damage are the siting and orientation of structures and their connection to each other; open space use; the construction of building façade elements, doors, and windows; the elevators; the heating, ventilating, and air-conditioning systems; the electrical systems; and the interrelation of these systems and the spaces and purposes they serve.

    Applying engineering knowledge to damage control would not be without economic cost, but it would undoubtedly reduce the danger of terrorist acts to human life with considerably less stress on the fabric of American society than a number of the political measures contemplated.

    A more promising program is the use of “sheltering in place” in the pressurized fire stair towers specified in new building codes. Larger pressurized shelter areas could be provided at nominal cost. Unfortunately, for these methods to be effective, fast, reliable detectors are required to activate controls and alarms. Dr. Steven Hatfill at the Army Medical Research Institute for Infectious Diseases proposes a two-step detection process using light scattering-type detectors to speedily detect weaponized C/B aerosols of one- to five-micron particle size and to activate alarms prior to identification of the toxic agents.

    Until such detectors are available, other research predicts that a reasonable level of protection may be possible by two continuous processes in building air-intake and air -distribution systems:

    • the use of high order in-line filtration and adsorption for both chemical and biological agents and
    • the use of an experimental in-line pulsed-light prophylaxis for biological agents (the developer claims a biological agent defeat/kill ratio of 99.99 percent).

    This is one more case in which casualties may not be reduced to zero, but, to the extent that the program proposed is successful in preventing or mitigating the effects of an attack, it is more desirable and will be more effective than any reactive program. The conference was organized for this reason. We believe that we can find the answers if we can only frame the questions.

    The Architectural Engineering Division of the American Society of Civil Engineers has formed a Task Committee to study the technical, economic, social, and environmental aspects of this problem and its opportunities. It is anticipated that among the results of this study will be the development of guidelines for designing and constructing buildings to mitigate the effects of urban terrorism.


    On March 3, 1999, a Joint Working Group on Defense against Chemical and Biological Terrorism was formed by the responsible elements of the Departments of Defense, Energy, and Justice, together with representatives of the United Engineering Foundation, Architectural Engineering Institute, American Society of Civil Engineers, American Institute of Chemical Engineers, American Society of Mechanical Engineers, and the AEGIS Institute to pursue the program of prevention, protection, and mitigation of chemical/biological vulnerability set forth in the above summary. Norman Glover has been appointed chairman of this Joint Working Group.

    For further information, contact the Joint Working Group Defense Against Chem-Bio Terrorism; 375 Hudson Street, 12th Floor; New York, NY 10014.

    AEGIS Institute Inc., New York, New York


    1. Miller, J., W. Broad, “Clinton Describes Terrorism Threat for 21st Century,” New York Times, Jan. 22, 1999.

    2. FEMA/ASCE Report 277, “The Oklahoma City Bombing, Improving Building Performance through Multi-Hazard Mitigation,” Aug. 1996.

    3. Corley, E., C. Thornton, “The Oklahoma City Bombing, Further Discussions,” ASCE National Convention, Minneapolis, Minn., Oct. 1997.

    4. Glover, N., “Creating the Protective Environment,” ASCE Seminar, presented at General Services Headquarters, Washington, DC, Apr. 28, 1998.

    5. General Accounting Office Report, “Chemical and Biological Defense: Emphasis Remains Insufficient to Resolve Continuing Problems,” Mar. 1996.

    6. OSD, “Proliferation: Threat and Response,” 1996.

    7. U.S. Congress, Office of Technology Assessment, “Proliferation of Weapons of Mass Destruction: Assessing the Risks,” Government Printing Office.

    8. Danzig, R., “Biological Warfare: A Nation at Risk-A Time to Act,” Institute for National Strategic Studies 58, 1996.

    Summary of Proceedings of Combating the Vulnerability of Buildings and Infrastructure to Chemical and Biological Attack

    Following is a summary of ideas and programs presented during the conference:

    • PROTECTS (Program for Response Options and Technology Enhancements for Chemical/Biological Terrorism in Subways), presented by Dr. Anthony Policastro, Argonne (IL) National Laboratory: PROTECTS is envisioned as a conceptual three-phase, five-year (1999-2003) plan to prepare all types of U.S. subway systems (from old to modern) to better respond to chemical/biological (C/B) incidents. It will entail a cooperative effort involving transit authorities, federal/state/local emergency response organizations, and government officials and an integrated approach covering preplanning and emergency response. New technology (hardware and software) and advanced emergency management tools for incident response will be developed, technical assistance and a practical approach for implementing the plan in all U.S. subway systems will be provided, and engineering solutions to limit the impact on humans and the subway system will be covered.

    PROTECTS has seven major elements:

    1. Modeling and Simulation-identifying the consequences of a range of scenarios, identifying the best mitigation and consequence management strategies, and assessing the effect of containment barriers. The Washington METRO system will be the initial study site. Additional subway systems will be added.

    2. Engineering: Flow Control-achieving tunnel and station air-flow patterns that will confine the C/B agent plume to a particular section of a tunnel or disperse the plume as rapidly as possible and clearing escape routes for passengers and access routes for emergency response personnel.

    3. Testing and evaluation-validating the efficacy of the flow-control system by field testing.

    4. Detection of chemical and biological agents-combining C/B sensors and real-time computer simulations for crisis management, evaluating sensor options, and factoring in new sensor technologies as they become available (in the meantime, human observation and intelligence information will be used to identify an agent).

    5. Human factors-determining how to best manage people and enable them to most efficiently communicate information during an emergency and to take part in their own rescue.

    6. Emergency management and training-implementing strategies developed from the first five elements: developing first responder procedures; developing Operations Control Center protocols; coordinating rescue operations with city, state, and federal response organizations; and developing a manual and a computer training program.

    7. Decontamination and recovery-evaluating the most effective methods for decontaminating subway tunnels and stations and developing new methods if present ones are found to be inadequate; protocol for sampling after cleanup; and periodic updates to incorporate scientific advancements.

    • Classifications of Chemical Warfare Agents, presented by Dr. Mohamed Mughal, Domestic Preparedness Program, Soldier and Biological Chemical Command, Aberdeen (MD) Proving Ground-covered the four classifications of chemical warfare agents (nerve agents, vesicants, cyanide, and pulmonary agents) and their various components; the physiological effects; treatments; and decontamination.
    • Biological Agents from an Engineer’s Perspective, presented by Dr. Dick Hutchinson, Domestic Preparedness Program, Soldier and Biological Chemical Command, Aberdeen Proving Ground-biological agents: definition, general properties, physiological effects (signs and symptoms), pathogenesis, residual hazard, and building protection.
    • CW [Chemical Warfare] Detection: Past, Present, and Future, presented by John Avolia, FAA Program Manager, Barringer Instruments, Inc.-today’s chemical detection systems; early warning; first response; decontamination; point detectors (handheld, vehicle-mounted, and transportable); surface acoustic wave (SAW), under development; ION Mobility Spectrometry (IMS) deployed with ongoing R&D; other techniques; detection problems, CW threats (typical urban scenarios); detection requirements (what is needed?); early warning, city perimeter and interior, buildings, and mass transit; first response and decontamination; Barringer’s Ionscantrademark, an IMS-based explosives and narcotics detector; IMS.
    • Joint Biological Point Detection System Program, presented by LTC Mark L. Grotke, product manager, Joint Biological Point Detection System-develop a common, integrated suite of biological point detection components for use by all military services: requirements, desired capabilities, platform variants (shipboard, fixed-site, vehicle-mounted, portable), acquisition strategy, test and evaluation, functionalities: triggering (using device that senses changes in background aerosol levels), collection (device that captures and/or concentrates aerosol particles), detection (device that classifies background changes as “suspect”), identification (device that identifies biologicals to genus and species), local/remote operations, communications, integrated logistic support. He also gave an Overview of Biological Detection Methodologies, general considerations; types of triggers, collectors, detectors, and identifiers; variations; future directions; realities (high cost, associated false alarm rates, false positive rates, sensitivities, limited number of agents).
    • Overview of Biological Detection Methodologies, presented by Lieutenant Colonel Mark Grotke, product manager for the Joint Biological Point Detection System-general considerations; types of triggers, collectors, detectors, identifiers; variations; future directions; realities (high cost, associated false alarm rates, false positive rates, sensitivities, limited number of agents).
    • CONTAIN-An Integrated Analysis Tool That Can Be Used to Assess Consequences of Dispersal of Hazardous Agents In Facilities, Sandia National Laboratories, Albuquerque, New Mexico-a control plume approach to address an arbitrary network of volumes (rooms and halls) and structures; the code is a fully coupled thermal-hydraulic, gas, and aerosol mode designed to support probabilistic risk assessments that entail sensitivity analyses, parameter studies, and evaluation of trends and uncertainties for large complicated problems; tracks the release, transport, and fate of hazardous gaseous and aerosol material through a complex multicompartment facility with engineered safety features designed to mitigate the release of toxic agents (originally developed for nuclear containment, now used to plan C/B defense of vulnerable facilities.
    • Chemical and Biological Infrastructure Protection, Michael Janus, PE, project manager, Battelle Edgewood Operations, Bel Air, Maryland; Robert Rudolph, James McNeely, Battelle-infrastructure protection process, C/B infrastructure protection options, appli

      Summary Notes: Mitigation of Chemical/Biological Attacks in New Building Construction

      The conference attendees participated in a number of working/discussion groups. A record of one of these, “Mitigation of Chemical/Biological Attacks in New Building Construction,” was prepared by Valentine A. Lehr, P.E., founder and principal of Lehr Associates, which has provided services for projects on six continents.

      • Chemical/biological protection in new buildings must be considered in design in the same way as specialty systems such as security, lighting, and so on.

      • A clear understanding of the design techniques used in commercial buildings is needed to deal with the mitigation techniques suitable for chemical/biological (C/B) protection.

        • At present, the interest in mitigation is centered with the Government for governmental buildings. If the aim is to protect all citizens (and not only soldiers), then the private sector needs to be encouraged to consider mitigation. Although financial institutions and the headquarter offices of major corporations have expressed some interest, the issue is not a consideration for the majority of private sector construction.
        • There is a critical need to develop a risk evaluation approach that will enable the quantifying of “reasonable” extra costs for various levels of protection. The prime tool here would be a matrix with various threat materials listed on one ordinate and viable solutions on the other ordinate. The intercept would then identify important issues and costs.
        • Efforts are needed to interest manufacturers in developing products suitable for enhanced building C/B protection.
        • One possible alternative to conventional approaches would be the development of “smart materials” that would act as a construction element and a passive means of continual protection.
        • The question arose, “Is terrorism a liability issue?” If insurance, particularly business interruption insurance, comes into play, the insurance industry will become a focusing agent for action.
        • C/B attacks are directed toward “appealing” targets. The best strategy for an owner/tenant would be to make the building “unappealing.”

        Some strategies that could be used in buildings that are always de facto appealing targets, such as embassies, would include developing architectural designs to protect air intakes, breaking the building into numerous small zones, restricting access to mechanical equipment areas, and providing video monitoring of critical points in the system.

        NORMAN J. GLOVER, FASCE, FIStructE, is executive director of Aegis Institute, a nonprofit foundation devoted to anti- and counter-terrorism technology, and chairman of the Board of Governors of the Architectural Engineering Institute of the American Society of Civil Engineers. He previously chaired the Facilities Planning and Program Management Committees and the Working Group on the Mitigation of the Effects of Terrorism of the Architectural Engineering Division of the American Society of Civil Engineers. He is a civil engineering graduate of Columbia University and has served for more than 25 years on the School of Engineering and Applied Science Advisory Council. He has done graduate work at Columbia and Harvard Universities, the Naval War College, and the City University of New York and is an adjunct professor of international hotel development at New York University.

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