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Chemical/Biological Threat to Air Transportation

Historically, most terrorist attacks on civilian targets have involved the use of firearms or explosives, and current defensive strategies are aimed at preventing attacks perpetrated by such means. However, the use of the nerve agent sarin in 1995 to attack the Tokyo subway system, the use of the U.S. mail in 2001 to distribute letters containing anthrax spores, and the discovery in 2004 of the biological toxin ricin in U.S. Senate Office Buildings in Washington, D.C., demonstrate that chemical and biological agents have been added to terrorists’ arsenals.


Terminals generally accommodate the large numbers of the traveling public that move through them with residence times of about 1 to 2 hours. There are also large numbers of visitors who are not traveling but are dropping off travelers at check-in areas or waiting to meet travelers in the baggage claim areas. Their stay at the facility would typically be at least 30 minutes, although such assumptions should be checked against actual data. In addition, there are a significant number of airline, concessions, ground transportation, and security personnel working within airport terminals around the clock. In passenger ticketing/check-in areas, there are numerous entry and exit points.


History has shown us that airports have become desirable targets for terrorist attacks. The Chemical, Biological, Radiological, and Nuclear (CBRN) threat presents a more complex conundrum and is much more difficult to detect and deter, as the technology to identify such risks is both limited and costly.


According to the 2014 Communication of the European Commission on a new EU approach to the detection and mitigation of CBRN-E risks there are ample opportunities for a determined terrorist outfit to access CBRN material. Thefts and misplacements of CBRN material occur on hundreds of occasions each year and there is a particular risk that terrorists might use sarin, ricin, or anthrax. More than 150 cases of trafficking of radiological and nuclear materials are reported annually to the Incident and Trafficking Database of the International Atomic Energy Agency (IAEA).


Airports present an attractive target for this type of attack as the chemical or biological agent can be easily concealed within a person’s luggage and without names or bag checks on everyone who enters the front door, it is difficult to keep a professional terrorist—especially one who has a ticket—away from the facility.


Most passengers are carrying at least one bag, if not more, and a very large number of checked bags are passing through the facility from check-in areas to aircraft. There is a constant movement of materials and supplies throughout all areas of the facility, and large amounts of cargo and shipping containers are also moved through on their way to the aircraft.


Airport terminals are typically large, open spaces with relatively uniform physical configurations that include, for example, ticketing/check-in areas, baggage claim areas, security checkpoints, concessions, restrooms, and departure gates. These large spaces require heating, ventilation, and air conditioning (HVAC) systems to maintain acceptable air quality. Some areas are open to the general public, and others are restricted to passengers, employees, and/or security personnel.


The aircraft itself comprises space very different from that of the terminal. The cabin features a relatively small, confined space with a very high density of passengers, crew, and carry-on bags. The minimum passenger residence time on an aircraft is about 1 hour, with maximum times stretching to 14 hours for very long distance flights.


Virtually all aircraft have the same basic physical configuration. The Environmental Control System (ECS) is crucial for maintaining air quality during a flight, and the vast majority of aircraft have similar localized airflow patterns. During a flight on a typical airliner, 50 percent of outside air is mixed with 50 percent filtered, recirculated air, with complete exchange of the cabin air volume every 2 to 3 minutes. Special consideration is given to air supplied to the cockpit.


Although there are few access points to an aircraft before a flight and although passenger access is carefully controlled, a significant number of airport personnel have access to the aircraft between flights. These include baggage handlers, cleaners, food service personnel, maintenance personnel, and refuelers. In addition, while the aircraft is on the ground, it is connected to an external HVAC system. These various factors suggest that aircraft face a significant vulnerability to chemical/biological attacks while they are on the ground.


Airports, bus stations, train stations, and rest stops are all places travelers can be exposed to the virus in the air and on surfaces. These are also places where it can be hard to social distance. In general, the longer you are around a person with COVID-19, the more likely you are to get infected. Air travel requires spending time in security lines and airport terminals, which can bring you in close contact with other people and frequently touched surfaces. Most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on airplanes. However, social distancing is difficult on crowded flights, and sitting within 6 feet of others, sometimes for hours, may increase your risk of getting COVID-19.


The focus of the antiterrorist efforts of the U.S. air transportation system to date has been on the detection of concealed arms or explosives; essentially no capability exists to detect chemical or biological warfare agents effectively and affordably or to mitigate the impact of a terrorist attack involving these agents. Thus, a terrorist runs little risk of being caught or discovered before perpetrating an attack, and the number of people exposed to the agent would depend only on how effectively the perpetrator could disseminate it.



Chemical / Biological Threat agents

Many types of threat agents might be used in an attack on the air transportation system. Each has its own set of physical, chemical, and biological characteristics, which would determine how lethal and widely dispersed the effects would be. Four different categories of threat agents can be distinguished:

Fast-acting chemical agents. Individuals exposed to these agents begin displaying symptoms within seconds or minutes. Examples of such agents include the neurotoxic agent sarin, the choking agent chlorine, and the blood agent hydrogen cyanide.

Delayed-acting chemical agents and biological toxins. With agents in this category, which includes some chemicals as well as large-molecular-weight toxins produced by certain biological organisms, exposed individuals would not begin exhibiting symptoms for hours or days. Examples of such chemicals include sulfur mustard; biological toxins include ricin and botulinum toxin.

Slow-acting, noncontagious biological agents. These agents, which include viruses as well as the bacterial causative agents for anthrax and tularemia, produce no initial symptoms, but cause flu-like symptoms after a few days or weeks. Some, such as Bacillus anthracis, can be disseminated either in the form of spores or as vegetative cells.

Slow-acting, contagious biological agents. This category of agents, which includes the virus that causes smallpox and the bacterium that causes pneumonic plague, produces no initial symptoms upon infection but typically causes flu-like symptoms after a few days or weeks. Infected individuals are usually contagious after they are symptomatic.


CBRN Strategy for Air tranportation

Every airport should have detection, protection, and response strategies as part of their overall airport security planning, business continuity, and risk management processes.

Providing serious consideration to training onsite airport RFFS in CBRN response enables airports to effectively respond to any incident in the shortest possible time frames, while awaiting support from the local authority and/or municipal RFSS.

A good place to start is the airport RFFS in Initial Operational Response (IOR) protocols with regard to the initial containment and decontamination process – which can go a long way to restricting the potential spread dependent on the agent and type of contamination.


Threat Detection

One common characteristic of many chemical agents is that they tend to be relatively fast acting: that is, victims begin to exhibit symptoms of distress within seconds to minutes after exposure to the agent. This almost-immediate showing of symptoms has implications for defensive strategies based on detection systems, since the chemical agent released in an attack would reach and produce a response.


A common characteristic of biological agents is that they are slow acting: although exposure may occur rapidly, victims’ symptoms may not appear for several hours to several weeks, depending on the agent. Similarly, delayed-acting chemicals and biotoxins would produce no symptoms for several hours to several days. In that amount of time, airport passengers and workers would have dispersed to a wide variety of destinations. Thus, for attacks involving slow- or delayed-acting agents, technologies for early detection become more important—a detector alarm may be the only indicator for several days that an attack has taken place.



USAF analysts conduct vapour purge test on cargo plane

US Air Force (USAF) 711th Human Performance Wing’s chemical, biological, radiological, and nuclear (CBRN) analysts from Wright-Patterson Air Force Base (AFB), Ohio, have conducted the first vapour purge test on a cargo aircraft at the 19th Airlift Wing at Little Rock AFB, Arkansas. Vapour purge tests were conducted to determine the time required for a chemical contaminant such as tear gas to be removed from an aircraft.

This cargo aircraft test forms a part of a series of experiments that the analysts will carry out on aircraft across the US Department of Defense (DoD). The test is also aimed at finding out the potential best practice to efficiently reduce the number of chemical particles in the air. During the test, a C-130J Super Hercules aircraft was filled with methyl salicylate using a custom-made pump.


Following this, advanced measurement tools were used to monitor the concentration of the chemical in the air and the time taken for the contaminants to purge from the aircraft’s environmental control system (ECS). USAF 711th Human Performance Wing research bioenvironmental engineer Major Michael Horenziak said: “We’re introducing a chemical into the aircraft that’s a known stimulant for nerve agents and has been used on several other experiments across the DoD.


“We try to simulate the plane coming in sometime after it comes in contact with a chemical. After filling the plane with the particles, we measure how long the ECS system takes to create a safe environment inside of the aircraft for anyone on board.” Using experiment results, analysts will be able to recommend equipment and uniform changes for aircrew in order to minimise their fatigue and provide them with maximum comfort while maintaining personnel safety and effectiveness. Such tests were last completed in the 1970s and 1980s and now would be considered obsolete.


USAF 711th HPW senior CBRN analyst William Greer said: “The information that we learn from this will be used by the people who develop the next generation of aircrew ensembles, providing equipment that allows airmen to do their jobs more efficiently, more effectively and not suffer some of the encumbrances that come with the equipment we’re wearing now. “The numbers from this are being measured with equipment that’s generations ahead of the equipment that was used during the original tests. “There have been similar types of testing, but the approaches we’re using here, such as the equipment and the methods we employ, are giving us a much clearer picture of how the threat will affect aircrew both short and long-term.” The vapour purge test aims to improve the operational capabilities of aircrew across the DoD in chemically contaminated environments.



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