Harmful Biological Agents in a Public Facility: The Airport Scenario
Although all commercial airports have the same basic functions, they vary widely in design and management across the United States—and even more so throughout the world. If we limit our attention to the larger U.S. airports—those that seem of greatest concern in contemplating the consequences of an act of bioterrorism—there are some general characteristics we can list. Modern airports are complex places, resembling small cities in many respects. They often have dozens of buildings, including passenger and freight terminals and a host of maintenance, operational, and support facilities that include extensive areas for fuel storage.
Those “small cities” are often populated by tens of thousands of people: the travelers, the family and friends who might accompany them, the shippers who convey air freight to and from the facility, and also the employees. Airports in the United States accommodate more than 650 million passengers each year, and the largest—those in Atlanta, Georgia, and Chicago, Illinois—handle over 60 million annually. Airport employee populations can be counted in the thousands, and sometimes in the tens of thousands. The number varies, depending on the size of the airport and on the number of aviation-related facilities. Some major airports in the United States occupy as little as 600 acres; others cover more than 10,000 acres. Often, there also is major commercial and residential development crowding nearby, and at the smaller facilities, surrounding neighborhoods are part of an “airport city,” a fact that is important for the technical and the social dimensions of dealing with an act of bioterrorism.
Airport passenger terminals include two general kinds of space—public space, routinely used by the traveling public, and support space, which houses
baggage processing, mechanical rooms, offices, storage, and a host of other activities. Although the baggage-handling spaces are not usually partitioned, other support spaces tend to be subdivided into relatively small rooms.
Although it is not outside the realm of possibility that a biological attack could be launched against any element of an airport to disrupt the overall operation, the passenger terminal would seem to be the most likely target. That terminal usually would be a large single building or complex of buildings that can range in size from several hundred thousand square feet to several million square feet. When the terminal consists of several buildings, they often are connected to facilitate easy movement of passengers and employees. The result is that air also mixes and spreads easily within the facility, and biological contaminants could migrate easily as well. Airport terminals are tied into the full range of utilities needed to serve large modern buildings. Often the utilities are linked to airport-wide plants by tunnels that are large enough to accommodate foot traffic by maintenance workers and, occasionally, by small vehicles. Another key functional element of all major airports is ground transportation for passengers, including public transit systems, car rental agencies, and facilities for privately owned vehicles. Sometimes these services are tied to enclosed or semi-enclosed spaces that also connect to passenger terminals.
All of the terminal spaces described above are served by heating ventilation, and air-conditioning (HVAC) systems that are similar to those in other large commercial buildings. There are greatly varying levels of sophistication and automation in airport HVAC control systems, largely as a function of the system’s age. Although all move air into zones throughout the building to maintain appropriate temperature and humidity, the degree to which air flow can be rapidly modified or halted varies widely. HVAC systems are, of course, a major factor in any attack that would seek to release a biological agent into an airport terminal and therefore a major factor in the contamination that must later be remediated.
Few generalizations can be made about the interior materials in airport passenger terminals. Most have hard surfaces for floors and walls to facilitate maintenance and longevity, but some have softer materials (like carpeted floors) despite the need for frequent replacement. Such site-specific particulars as surface materials will have a major influence on decontamination after a biological attack.
Another consideration for decisions related to decontamination after a biological attack is that at any given time some aircraft generally are parked at a terminal. Those planes often are attached to the building by loading bridges, which in many respects render the aircraft an integrated element of the terminal building. Similarly, rail systems sometimes run through or are attached to airport buildings. Thus, contamination could extend to docked aircraft and rail systems, and possibly to other locations served by these aircraft or rail systems. The potential for contamination of docked aircraft and rail systems would be influenced by several factors, such as the method used at a particular gate for provid-
ing HVAC to a parked aircraft. Sometimes the aircraft’s on-board systems are used, but there is a range of other means—even including HVAC supplied from the central plant that serves the terminal building. The connections between a terminal, aircraft on the airside and trains on the landside, increase the complexity of decontamination at the terminal in the event of a biological attack.
The number of people in an airport terminal at a given time depends on the schedule of airline flights. At some airports the pace of flight activity is relatively even throughout the operating day, so that the terminal’s population remains steady as well. For a hub airport, the pace is set by the rhythm of the connecting banks of flights, and populations can vary widely throughout the operating day.
PLANNING CAN MAKE A MAJOR DIFFERENCE
Transportation agencies—airports in particular—are experienced in planning measures to prevent various forms of attack, including biological attack. Those plans, which include steps such as securing building air intakes, should continue to be a high priority, both in existing and in new facilities. The same agencies for many years also have recognized the benefits of planning for an emergency response to an attack. Airports routinely prepare, maintain, and periodically exercise emergency manuals, which set out the steps in considerable detail.
The unfortunate reality is that we could face the need to decontaminate a major transportation facility, and we would need to work through the complex technical and social decisions involved in such an effort, up to and including the decision to reopen the facility. The framework for the process is outlined in Chapter 11. It would seem prudent that the well-accepted practice of planning specific portions of a prevention and emergency response to a potential biological attack should be extended to include the decontamination and reopening of a given facility. Such preparation could substantially hasten the reopening of a facility that has been the target of such an attack.
The first, and perhaps most straightforward, step would be the identification of people—with specific contact information—who would assist in verifying the weapon used in an attack and the entities that appear to be the best candidates to assist in decontamination and sampling. In addition, specific contact information should be compiled for those local, state, and federal governmental agencies that could have a role in decontamination and reopening.
The next step would be the collection of site-specific engineering data, which would be essential for designing and validating the approach to sampling and decontamination. That information would include floor plans for the airport terminal, including equipment layouts, and an inventory of interior surface materials. Often the information already exists and it will be a matter of isolating it for ready access when needed. However, if the desired data do not already exist they might need to be assembled for this specific purpose. Examples include assess-
ments of the relationship of the various potentially contaminated spaces to other spaces or current, reliable data on the movement of air within the building as HVAC equipment operates. One reason gathering this information in advance is a concern is that airport terminal buildings often are built and modified in a series of contracts, usually administered by different entities. The airport owner might build the concourse, an airline might use a different contractor to construct a club in that concourse, and a concession operator might open restaurants or shops under yet another contract in the same concourse. Facilities might have been modified or renovated since the original construction documents were produced, and not all airports have effective control over maintaining current as-built drawings for all their tenant spaces. In that case, contract documents might not be conveniently located or organized to give a comprehensive and timely picture of current conditions in the terminal.
Although the normal operation of a building requires some continuing information on the subject, most likely, only new tests would yield the detail that would be useful for understanding the pattern of contamination that sampling a contaminated facility would suggest. In addition to gathering information on the movement of air within a facility, it would also be useful to sample the air within the facility to determine background concentrations of microorganisms. Sampling should be done over a range of occupancy and weather conditions as well as at modal connection points, such as rail stations if they are present. Even then, the sampling data would, at best, provide only a loose reference point for future comparison because of the sensitivity of air content and quality values to a host of factors that vary widely from day to day and even from hour to hour. Nonetheless, some prior reference points could provide valuable information for beginning decontamination with an intense focus on air content issues.
Another aspect of planning would involve contingency plans for maintaining the airport’s service. Planning for the potential loss of capacity could minimize disruption to the transportation system. For a major connecting airport dominated by a principal carrier, that airline might be able to reroute a portion of its schedule through another airport to compensate for the connecting traffic capacity taken out of service because of decontamination efforts. At an origin-and-destination airport, the contaminated terminal space might represent the entire capacity of one or more carriers. In that case, planning could consider the possibilities for relocating flights from the affected areas to an unaffected terminal, if available, or to another regional airport. In either case, significant capacity replacement could be required for the duration of the decontamination effort.
An additional step deals with identifying the entities that should be represented in a group that would oversee the process of actual decontamination and reopening of an airport. That could be the most important step for achieving rapid decontamination and reoccupation. Ultimately, that group will be looked to for assurance that a once-contaminated facility is safe to reopen. In some ways, that step also could be the most difficult to accomplish. However, if the groundwork
is not done in advance, the formation of such a group under the intense stress, pressure, and publicity of an actual event will make any planning difficulties look small by comparison.
The makeup of such an Operations Working Group is discussed in Chapter 11. In an airport, that group should include knowledgeable technical people, those with onsite engineering skills; employee representatives, including those from unions, airlines, and other companies that do business in the facility; representatives of neighboring communities and of more distant communities that depend on air service through the facility (the “spokes” in a “hub and spoke” arrangement); and other parties whose views during and after the cleanup would be valuable and credible. That body should come together at the planning stage, and periodically thereafter, so it achieves a sense of mission and cohesion, and to the extent possible, so that its members would be able to work their way through the shock and horror of the overall subject. That way, if the group were faced with an actual event, those very human reactions might be mitigated.
The final step is the development of a framework for public communication. Anticipating the confusion that a biological attack would create—confusion that could well remain throughout the decontamination and reopening phases—it is highly desirable that a transparent and straightforward but disciplined communication process is worked out beforehand with the group assembled. Research done early in the planning process can provide valuable information about stakeholders, available communication channels, trust issues, perceptions of risk, and appropriate spokespersons who could help with the communication needed in the aftermath of an attack. Advance discussion of potential scenarios can be useful for increasing trust and could decrease problems that could arise from a lack of familiarity with the issues.
FINDINGS AND RECOMMENDATIONS
Airports, particularly passenger terminals at airports, are vulnerable to biological attacks, because of the high-profile nature of aviation and because of the densely populated, large, often interconnected interior spaces that such terminal facilities comprise. Aircraft often are connected to terminals so departing aircraft could spread a pathogen to distant points if a biological attack on the terminal were not immediately recognized. The same threat is also presented at airports served directly by urban transit systems—such as rail lines—that are connected to a passenger terminal.
To deal with the aftermath of a biological attack, airport operators should anticipate the need for access to diverse and highly specialized resources, including
information on control of air flow. Airport operators should assemble, adopt, and maintain detailed plans to identify, contact, and mobilize those resources. The plans and associated resources should be updated periodically, and they should be stored in locations that would be accessible in the case of an event.
Airport operators are experienced at preparing, adopting, and using specific procedures to cope with the immediate-response aspects of a broad range of emergencies. The same aggressive approach to planning could be usefully applied to the projected aftermath of a biological attack, including the decontamination and reopening sequences that such an attack would occasion. In the event of an actual biological attack, the availability of a soundly drawn plan derived from a comprehensive process would certainly hasten the reopening of a facility.
Plans should contain pertinent physical information on facilities, including floor plans, material characteristics, air circulation patterns, and air sampling data. The plans also should identify, and provide current contact information for, organizations and individuals who could be rapidly mobilized to identify the attacking agent and those who would be available to assist with the actual decontamination.
Acceptance of the decision to reoccupy a facility will be more successful if an Operations Working Group is formed before an event occurs, and if that group includes people with scientific, technical, and medical expertise and those whose daily lives would be affected by contamination of the airport.
Planning should identify the interested parties, form them into a working group, and have them interact regularly in anticipation of coming together to guide an actual recovery effort. That effort should be executed in a manner designed to maximize trust among the various participants and stakeholders.