The letter bombs that were sent to the National Press Building in Washington, D.C.,
earlier this year are just the latest reminder that any business can become the target of
a potentially explosive attack. However, because many companies experience few, if any,
live bomb incidents, it is easy for senior managers, secretaries, and mail room employees
to be lulled into a false sense of security and a belief that "it could never happen
here."
Faced with this challenge, it is up to the company's security manager to remain vigilant
and find the right combination of technology and training procedures that will make
corporate executives and other employees less vulnerable if a bomb attack occurs.
In developing a bomb detection strategy, the security manager must keep in mind that
personnel and property cannot be completely protected. Although some sales people may
claim to have the magic bullet that stops bombs from entering the workplace, technologies
are merely tools--and expensive tools at that--to help tighten security.
Each bomb detection device represents only a layer of defense and will not detect every
possible explosive material. To be effective, these tools must be operated by a
well-trained staff that takes its job seriously. In addition, bomb detection technologies
should be purchased to meet very specific needs. An x-ray machine that is too small for
the average mail tray, for example, will not be effective in a company's mail room and
will eventually be switched off and ignored by frustrated employees.
The security manager has a wide range of choices when shopping for bomb detection
technology, including x-ray machines, scanners, sniffers, x-ray sprays, and chemical
reagents. While the x-ray machine is effective, most other technologies have either not
evolved enough to be used as standalone systems or are simply not effective for most
corporate environments.
Some of these bomb detection technologies can actually be dangerous to staff if not used
properly. The security manager must determine how the company will use the device and
then test each technology to see whether it fits within the corporation's defensive
shield. Employees should then receive proper training, either from a local bomb squad or
a qualified explosive technician, before any of these devices are used.
X-ray machines.
The x-ray machine is the safest and most effective tool for screening mail, briefcases,
purses, and other incoming containers for explosive devices. Used in mailrooms and as
part of access control systems, these devices can cost anywhere from $2,500 to more than
$150,000. The price depends on three factors: the type of x-ray technology, the style,
and the power. In addition, security managers may need to choose among several standard
features and options, although the choice may not affect price.
Technology.
Three types of x-ray technologies are on the market today, including a straight x-ray such as that used in a dentist's office to examine teeth; dual energy; and
backscatter, a relatively new technology.
The straight x-ray is the least expensive and the most typical technology found in
corporations. The machine shoots an x-ray beam through a package and presents a
black-and-white image on a monitor. Most machines come with a color enhancement feature
that is effective in exposing suspicious items that can fit in envelopes or packages.
Dual energy technology is another popular x-ray used by corporations, government
agencies, airports, and other organizations. It shoots two x-ray wavelengths through a
package, allowing an operator to distinguish between organic and inorganic materials as
they pass through the machine. Organic materials, such as a leather briefcase, paper, or
a sandwich, are displayed on the screen in red or orange, while inorganic
materials, metal pens, clips, or umbrellas, for example, are shown as green or blue. The
technology is designed to help operators better distinguish between objects.
Dual energy technology is an add-on feature to straight x-ray and will raise the price of
a machine by between $4,000 and $10,000. With this option, a second monitor is added that
displays the dual energy images. (The first monitor displays images from the straight
x-ray.)
The technology can be somewhat effective if used by trained operators. However, the
security manager should be suspicious if the vendor claims that explosives are easily
detected because they are made of organic materials and will be displayed as orange on
the monitor. While it's true that some explosives--such as C-4, dynamite, and TNT--are
organic and will be identified by dual energy technology, many explosive compositions are
not organic and will not show up as orange. This is true of black powder, sodium
chlorate, flash powder mixtures, and other explosives that are commonly encountered.
Therefore, organic/inorganic screening may provide the operator with a way to separate
components of the image, but it will not tell the operator if an image contains
explosives.
Backscatter technology is designed to capture the portion of an x-ray beam that is
normally scattered and lost during operation. This method allows the machine to better
distinguish between different objects that are lying one in front of the other. The
system has two screens. One monitor displays items in the front of the package or
briefcase, the other displays objects located behind the first objects x-rayed. The
system is not foolproof, though. Dense objects or minimal shielding may absorb most of
the x-ray and hide suspicious items located behind them. These machines are also
expensive. A backscatter x-ray machine ranges from $54,000 to several hundred thousand
dollars.
Styles.
X-ray machines come in three basic styles, each designed for different applications: fluoroscopic, conveyor, and portable.
The fluoroscopic style, often called a cabinet style x-ray, looks like a small cabinet
and can be easily placed on a regular desk. Packages must be put into the device by hand
and viewed through an eyepiece on the side of the machine. Although these machines are
attractive to security managers because they cost under $10,000, they are not user
friendly. They are also time consuming and often ignored by personnel.
An x-ray machine with a conveyor belt is the most popular and most effective. This
machine has two open ends and a conveyor belt that moves through the device at about
forty-five feet per minute. One or two Super VGA monitors (depending on which x-ray
technology is used) allow operators to view the contents of packages as they move through
the x-ray beam.
Although expensive (these systems can run $15,000 to $75,000), a conveyor belt x-ray is
highly effective for both mail room and access control operations because employees will
use the easy-to-operate machines.
The security manager should look closely at the machine's inspection tunnel to ensure
that it will be able to fit large packages. In general, an inspection tunnel should
measure at least seventeen inches high if it is being used in a mail room. X-ray machines
at loading docks should have an inspection tunnel that is at least twenty inches high to
handle large packages. The widths of x-ray machines are fairly standard, running about
sixteen and twenty inches.
The security manager may also consider buying a lightweight portable x-ray device, which
can cost $2,500 to $40,000. These devices are for highly trained search teams or
executive protection personnel. Portable x-ray devices offer one of the best ways to
examine furniture, walls, and other stationary objects that a search team finds
suspicious. They can also be taken on the road by executive protection personnel.
Portable x-ray machines use one of two technologies to obtain the x-ray image. The most
common portable device consists of a portable x-ray source and a cartridge containing
radiographic film. The object to be examined is placed between the film cartridge and the
x-ray source. The x-ray is then shot through the object and onto the film, which costs
about $7 per frame. The film must be developed in a separate processing unit, which takes
several minutes to produce a photograph of the package's contents. These photographs look
much like the x-ray photos used by doctors to examine a broken arm. It takes practice to
get a usable image. Too much or too little energy will yield a photo that cannot be
properly evaluated. For example, if the operator uses too little energy, the underexposed
photo will be too dark.
A newer technology allows the image to be digitally recorded in real time on a computer
screen by connecting a PC or laptop to a plate that receives the x-ray beam. With this
technology, the x-ray beam is shot through the package and into the receiving plate,
which transmits the image through a cable to the computer. Package contents are displayed
on the computer screen, much like the larger x-ray machines operate. This method
eliminates the hassle of working with a film cartridge and dramatically increases the
functionality of the equipment. The digital technology costs about $30,000.
There are, however, some inherent risks when using portable x-ray devices. Unlike the
cabinet or conveyor type x-ray machine, the portable units emit radiation that could
cause long-term health problems if the operator does not take the proper precautions.
Operators must be conscious of where the portable x-ray is aimed to avoid exposing
themselves or others to the beam.
Power level. For most corporate environments, x-rays come in 60, 90, or 140 kilovolts of
penetration power. A company should use an xray with a minimum of 90 kilovolts, which
can penetrate 1/4-inch of steel or a full U.S. Postal Service mail tray. In general,
machines of 140 kilovolts are not needed in mail rooms, but they may be appropriate in
loading docks where packages are bigger. A 60-kilovolt machine will only see through half
a mail tray, requiring mail room personnel to frequently empty out trays or
bags, an inconvenience that may encourage them to stop using the x-ray.
The security manager must ensure that an uninterruptible power supply is used on the
x-ray system to help prevent picture loss during power outages. At a minimum, a surge
protector should be installed to prevent damage from electrical spikes.
Standards vs. options. Various features may be added to either a cabinet or conveyor
style x-ray. The security manager should consider how the machine will be used before
determining which features are necessary.
For example, machines come with either movable or attached keyboards--which are used to
operate the x-ray. Movable keyboards offer the most flexibility, especially if the
company plans to move the machine between duties.
In addition, the security manager should ensure that the straight x-ray has a color
enhancement capability, which is not the same as organic and inorganic detection. A color
enhancement feature--which should not add any additional cost to the system,
allows an operator to see color with the push of a button so that he or she can further evaluate a
suspicious image. The colors relate to the density of an object, not its actual color. In
one system, for example, dark-colored or dense items are displayed as a deep red, while
lighter objects are displayed in faint orange. Objects of medium density show as green.
Although black and white always gives the best contrast and should be used by operators
in most cases, color enhancement can help an operator focus on certain images once a
suspicious object has been identified. For example, let's say a pistol is sitting in a
briefcase next to an umbrella. Because the two objects are touching, they may appear as
one object on a black-and-white screen, making it difficult for the operator to
positively identify the weapon. However, because part of object looks like the barrel of
a gun, the operator switches to color enhancement. With this feature, the dense gun shows
up as a deep red, while the umbrella may come up green--separating the items as two
distinct objects.
Many xrays come equipped with standard or optional front and rear extensions. This is
especially true of the larger types, such as are seen in airports. These extensions can
add several hundred to several thousand dollars to the price. To save money, some
companies build their own extensions. One technique used in mail room applications is to
attach a heavy wooden door (or other flat items that might be available at the company)
on stands that are perpendicular to the machine's inspection tunnel. Although not as
aesthetically pleasing as a manufactured extension, this technique gives the operator a
substantial amount of room in which to work. I recommend no less than four feet of
working room on all sides of a permanently situated machine.
Manufacturers also offer "edge trace" and "warning" options. Neither feature should
increase the cost of the system. The edge trace feature defines the edges of different
objects to help the operator better distinguish suspicious items. The warning feature
will red flag dense objects that cannot be penetrated with the x-ray. In one system, for
example, those objects will flash in red on the monitor. Warning options are best left
off an x-ray machine, however. Operators may become complacent and start relying too
heavily on a warning system that is far from perfect.
Training.
The xray is only as effective as the operator using it. Without adequate training, the
machine may as well be unplugged. For example, I recently conducted a test for a
potential federal client in Washington using inert explosive items. The inadequately
trained xray operator was so involved in looking at the blue and orange organic and
inorganic image on his dual energy x-ray screen that he ignored the obvious blasting caps
and other explosive components clearly visible on his other monitor.
Training should be provided to x-ray operators as well as security personnel and
supervisors. It should be tailored specifically to the employees' working environment and
include realistic scenarios. During training, operators should be able to distinguish a
suspicious item from a nonsuspicious item 100 percent of the time.
The security manager should not rely completely on the training provided by the product's
vendor. The manufacturer's training will explain how to use the machine, but it will
probably not be sufficient to adequately provide recognition skills.
Personnel should not be trained entirely with test items that look like bombs--which, in
the real world, may be disguised. Learning to recognize components like switches, wires,
detonators, and springs is far more important because they are normally the first things
to tip off an xray operator. Training that focuses on the details will be more
realistic, and x-ray operators will be far less likely to miss suspicious objects. One
way to do this is to show operators actual components, such as a detonator. (It should be
noted: When operators see a detonator on an x-ray screen, it is not important that they
know the object is a detonator, only that they know it is suspicious.) These components
should also be viewed from various angles on an x-ray monitor so an operator learns what
they look like from different positions.
The training should not teach personnel to examine an x-ray image for power sources,
initiators, and containers. Bombs do not have to be electrically initiated. In addition,
for mail room operator training, the security manager should not focus too much on the
more obvious letter and parcel bomb recognition points, such as greasy stains and
protruding wires. These signs have been widely publicized, and the bad guys now know that
they are red flags.
Operators at access points--who are faced with tangled images of purses, briefcases, and
bags--should also be taught when and how to conduct a hand search. Officers must know
what to look for or they are likely to miss suspicious objects. For example, I conducted
a test recently at an embassy in Washington, D.C., in which I entered the facility with a
briefcase filled with a pager, some tissues, pens, self-sticking notes, a handful of
inert electric and nonelectric detonators, electronic switches, and a stick of inert
dynamite. The contract guard looked into my briefcase, handed it back to me, and wished
me a nice day. He never challenged me on any of the obviously suspicious objects I was
carrying.
Supplemental technologies.
Other bomb detection technologies are now on the market, including sniffers, liquid
sprays, chemical reagents, and scanners. But should security managers use them?
Sniffers.
Vapor detectors and particle detectors, generally known as sniffers, identify explosives by their particulate or gaseous elements. When properly used, sniffers can
assist in the limited detection of a narrow range of explosive compositions, but negative
results always require other methods of screening. Like the other technologies that will
be discussed below, sniffers should only be used as one part of a layered bomb detection
strategy. They should never be used as a standalone system.
A vapor detector can identify volatile explosive compounds that have a high vapor
pressure, such as nitroglycerin found in older dynamite made with a formula that has
since changed. The device, which costs between $15,000 and $50,000, collects vapor
samples through a vacuum as it is run over a package, then analyzes them for vapors
generated by certain explosives. The results take only a few seconds to complete.
However, vapor detectors will miss explosives with a low vapor pressure, such as plastic
explosives, PETN, or black powder. In one test I conducted, for example, a vapor detector
failed to register a hit for a bottle that was filled with SEMTEC.
Before purchasing a vapor detector, the security manager should have the system
thoroughly tested by the local bomb squad to see which explosive substances it is capable
of detecting. In addition, the test should be conducted under realistic circumstances.
For example, since a criminal may go through great pains to seal explosives to make them
difficult to detect, the test team should seal the explosives tightly before putting it
in the package or briefcase that will be tested. Many labs simply test devices by
bringing them in direct, or at least close, contact with the explosive compound--something that almost never happens in the real world.
The second type of sniffer is a particle detector, which looks for trace amounts of
chemical compounds that may be found in some explosive devices. These devices analyze the
chemical signatures of the substances present on a package. The technology works on the
premise that if a person has been handling explosives, their hands will be contaminated
with residue, which will then be transferred to the package. Samples are collected either
through a vacuum hose or with swipe pads, gloves, and cards. The sample is placed into
the particle detector, which heats up the substance and displays the results on the
system's small monitor.
These instruments, which cost $25,000 and up, are ideally suited for detection of
postblast explosive residues, and have been helpful in investigations like the World
Trade Center and the Alfred P. Murrah Federal Building bombings. Particle detectors have
also been used with marginal success to sample rooms where suspected terrorists have
developed an explosive device.
In the corporate environment, particle detectors may be used as a component in a
multilayered access control system. They should never be used purely for deterrence. A
particle detector is currently being tested by one courthouse in the Northeast. Everyone
who enters the facility through this entrance (the device is being tested at only one of
the building's entrances) must touch a sampling card and place the card in the detector.
If the device detects explosive particles on the sampling card, it automatically locks
the bulletproof door and blocks the person from entering the facility. The verdict is
still out on whether this technology will be useful in this application.
Like the vapor detector, the particle detector should never be used as the only tool
available to the security professional--and all negative results should always be
verified with other screening methods, such as x-ray.
These instruments are best at identifying rarely used explosive compounds such as RDX,
PETN, HMX, NG, TNT, DNT, and some bulk nitrate explosives. Most bombings in the United
States consist of pipe bombs filled with smokeless or black powder, which particle
detectors are currently incapable of identifying. In rare circumstances, however, the
particle detector may detect nitrates present in high quantities.
Well-sealed explosives may not be identified by the particle detector. Also, because the
device requires operators to vacuum or swipe packages, the suspect items are subject to
handling forces that may cause them to explode. For example, to collect valid samples
with the vacuum model, the nozzle must have good contact with the surface of the package.
Vacuum systems that do not make contact with the surface are ineffective.
Although unlikely, the vacuum hoses may cause a sufficient amount of static electricity
discharge to initiate a bomb's firing components or explosive compounds. To use a
particle detector with a vacuum collection system safely, the hose should be shielded,
insulated, and grounded. Operators should use approved static discharge devices, which
can be acquired through industrial safety equipment suppliers. They should be grounded at
all times while performing screening. Operators should wear cotton clothing and never
wool, nylon, or other static-producing garb. Operators should never remove, add, or
adjust clothing during a test since this could cause static.
X-ray spray.
Xray sprays use a liquid aerosol compound to make paper semitransparent, exposing the contents of a letter or package. Dangerous drawbacks exist, however.
Moistened paper may short out an electrical circuit or react with the chemicals of an
explosive, causing a bomb to explode. Also, if the explosive device has a photoelectric
cell, causing the paper to become transparent could allow enough light to penetrate the
paper to initiate the firing mechanism. I consider liquid sprays too dangerous and
impractical to use.
Chemical reagents.
Chemical reagent detection kits cost about $200 and usually include three spray cans. The operator either sprays the package directly or sprays a sample card
used to collect a sample from the package. The item sprayed will turn various colors if
certain explosive compounds are present.
Reagents are insensitive and require a lot of explosive residue to test positive.
Reagents may react with explosive chemicals or cause shorts in firing circuitry. In
addition, the use of sampling cards subjects the suspect item to additional handling that
may cause it to explode. Although they are used by some corporate personnel, these kits
should be left to the local bomb squad.
Most reagents are toxic to some degree. If these kits are used in the United States, the
manufacturer is required to furnish a Material Safety Data Sheet (MSDS) for each chemical
in the kit. The federal Occupational Safety and Health Administration also issues
mandates for proper handling, storage, and use of the kits. Depending on the type of
reagents, requirements may include the use of protective equipment (such as gloves,
aprons, and eye and respiratory protection), storage lockers, and the posting of MSDSs.
Other countries may have similar requirements.
Scanners.
A relatively new type of bomb detection technology is the letter scanner. Regular envelopes go through this stationary device past a metal sensor. Scanners cost
between $160 and $3,500 and are relatively efficient for preliminary screening. However,
they should only be used in conjunction with x-ray machines.
A scanner cannot be used to screen boxes--the primary method for sending bombs. It is
also fairly sensitive and may beep if a letter contains several metal paper clips.
Because some machines are adjustable, operators sometimes lower the sensitivity level to
reduce the number of nuisance alarms. If sensitivity is reduced too far, however, the
scanner may miss bomb components.
Scanners have potentially dangerous drawbacks. Like radios and cellular telephones, the
electromagnetic radiation emitted from scanners could accidentally initiate the firing
system of a bomb if the explosive device is sensitive to an electromagnetic field.
Although I don't know of a case in which this has occurred, security professionals must
be aware of this possibility. The security manager should ask the manufacturer what type
of electromagnetic radiation is emitted by the scanner and what impact it might have on
explosive devices. If the manufacturer cannot answer these questions adequately, the
security manager should not purchase the system. It is also a good idea to ask the local
bomb squad about experience it may have with a particular detection product.
Hand-held wand.
Another type of metal detection technology is a hand-held wand, which
should only be used for access control. The wands are mobile and flexible and their
sensitivity level can be adjusted. However, wands are designed for gun, not bomb
detection. They should not be used to search for explosives except by a qualified bomb
technician under highly limited circumstances.
Security managers must be informed when purchasing bomb detection equipment. When
evaluating products, purchasers should ask themselves whether a product will increase
security or merely provide a false sense of security. Once technology is in place, the
security manager must remember that training and attention to policy and procedures are
critical components of a working bomb detection strategy.
