As terrorists continue to expand their knowledge base, their capability to unleash weapons of mass destruction on the American public moves from the realm of fictional thrillers to all-too-real concerns for public safety. A WMD attack by a terrorist, foreign or domestic, is not an "if" but a "when." It's a certainty that somewhere in the future American law enforcement will have to cope with the aftermath of a chemical, biological, radiological, or even nuclear assault.

A lot of excellent information has been made available to police officers about WMDs and their effects. But much of what has been published about one class of WMD, the radiological dispersion device (RDD) more sensationally known as the "dirty bomb," is inaccurate and likely to instill panic in both officers and the public. Let's take a look at how dirty bombs are constructed, what happens when they function, their potential for mass destruction, and how you, as a law enforcement officer, may be required to respond to such an attack.

A "dirty bomb" is quite simply a combination of radioactive material and something to disperse it, most commonly an explosive. Such a crude radiological weapon would likely be deployed by terrorists in a dense population center with the goal of killing and injuring as many people as possible for several square miles.

Such a scenario evokes images from an apocalyptic science fiction movie, streets and buildings once inhabited, now deserted. Fortunately, this description is a little long off the tee.

Radiation 101

To understand why dirty bombs are unlikely to be the nightmare vision that they are made out to be in the popular press, you have to know a little bit about radiation.

At its most fundamental, a radioactive atom is naturally unstable. Nature loves equilibrium, so the unstable atom tries to balance itself by allowing pieces to break off and fly away. These pieces can actually be thought of as energy, and this energy is referred to as "ionizing radiation" to distinguish it from other types of radiation such as heat or light.

A radioactive material is anything that contains these unstable atoms. We say radioactive material because, for ease of handling, controlling energy emissions, and reducing costs, radioactive elements are usually embedded into other, more stable elements.

Different radioactive materials have different properties, and some radioactive elements release more energy than others. This is a key issue with dirty weapons because for an RDD to be truly lethal, it must contain highly radioactive material. Dispersing low-energy radioactive materials accomplishes nothing more destructive than instilling widespread panic.

Low-energy radioactive materials seem scary to the uninformed, but they are actually quite common and relatively harmless, at least in the short run. Truthfully, we are almost always in contact with low-energy radioactive materials. For example, thanks to the development of insulated, energy-efficient homes, trapped radioactive radon gas, a byproduct of decaying natural radium, has become a health issue in many American communities.

And that's just one example of how much low-level radiation you encounter in a given day. Several industrial products in your home emit low levels of radiation and have done so for a century. Even the lowly banana emits radiation. And the Earth is constantly showered with radiation from space, or the sun, or a myriad of other sources.

Building a Bomb

To construct an effective dirty bomb is a daunting task. Notice I say "effective." Making a bomb that spreads radioactive material is child's play.

At its most crude form, an RDD consists of a radioactive product and a method of dissemination. Because RDDs are called dirty "bombs," many officers have the mistaken belief that all RDDs involve explosives like dynamite, plastic explosives, or even gunpowder. But anything that can disperse the product can serve as the dissemination element of an RDD. If the radioactive product is powdered, for instance, compressed gasses or a ventilation system could even be more effective than an explosive.

The tricky part of building a dirty bomb is not dispersing the radioactive material; it's acquiring and working with the material. As discussed, the radioactive payload of a dirty bomb must be very active or "hot," but material hot enough to provide a dangerous short-term dose when spread would be lethal to work with directly in producing the bomb. Of course, a well-heeled terrorist group could counter such difficulties by acquiring protective equipment, but that would certainly raise some alarms. Worse, a dedicated fanatic could sacrifice his life to make the bomb.

A more difficult obstacle to overcome is the nature of extremely active radioactive material. When placed in a confined space (like in a bomb), the interaction between radioactive atoms generates tremendous heat. Heat isn't a friend to the explosive core, and it also could potentially melt the radioactive product.

Finally, most highly radioactive products are clad in extremely hard metal alloys. Simply strapping them to a bomb would, in the opinion of most explosive ordnance experts, simply project the items, intact, a distance.

Exaggerated Effects

Even if a dirty bomb could be constructed and transported into a population center, the actual effects of its detonation might disappoint its builders.

Nuclear weapons expert Charles Ferguson, who serves as scientist-in-residence at the Monterey Institute's Center for Nonproliferation Studies, says that the lethality of a radiological attack has been overstated. "The most important point to get across to law enforcement officials is the fact that most radiological attacks will kill few, if any, people."

To illustrate Ferguson's argument, let's consider a theoretical bomb consisting of a five-pound explosive charge wrapped with an attached radioactive product in a flat open area. At the time of the blast, the greatest hazards to people would be from airblast (overpressure) and projection of debris just like they would experience from any conventional bomb. Remember, this is not a nuclear weapon and there is zero potential for a release of nuclear energy called a "yield."

Once the shrapnel stops flying, the greatest hazard to people near a dirty bomb detonation comes from inhaling the dust from the blast or having it in contact with their bare skin for a long period of time. Why bare skin? Simple, certain types of radiation can't even pass through your clothes.

ABGs of Radiation

There are three types of radiation-alpha, beta, and gamma-that will be of critical importance for all first responders to a radiological attack.

Alpha and beta radiation don't have the energy to penetrate a couple of pieces of paper; however, they can cause serious skin burns. The primary danger from material that emits alpha or beta radiation is from ingesting it or inhaling it. If ingested or inhaled and allowed to embed in the victim's body, over time even a dose of low-energy alpha particles could potentially cause long-term health effects.

Still, even in the worst case, the deadliest effects of alpha and beta radiation require long-term exposure. Not so with another type of radiation called "gamma." Sometimes called gamma "rays," gamma radiation is a characteristic of very hot radioactive material. It will penetrate walls of buildings, and even short-term exposure can be very dangerous.

Fortunately, gamma radiation is only emitted by hot radioactive material. And, as we've discussed, the most likely payload of an RDD will be low-level material. Consequently, it is thought by many, based upon years of data accumulated on personnel working with low-level radioactive materials, that the health effects of an RDD release will be more along the lines of increased risks for cancer-related problems years later, rather than radiation poisoning and immediate fatal effects.[PAGEBREAK]

The Attack

OK, now that we've discussed the basics of radiation, let's look at an RDD attack scenario.

A dirty bomb composed of explosives and radioactive material has just detonated in your jurisdiction. Here's what you can expect.

The weapon was driven into the city center in a rental truck. It was detonated and now you are dealing with the devastation of a major truck bomb attack. Buildings and vehicles are burning, bodies and pieces of bodies are scattered all over the street, and wounded and stunned victims are staggering away from the blast.

As there is with any bomb, there will be a cloud of dust and ash, except this dust is infused with radioactive material. Dust is heavier than air, so within a short period of time, it will settle. For a bomb this size it will settle about 1,000 feet from the blast.

Like the debris from any explosion, the dust from a dirty bomb will settle in a roughly roundish sort of cigar-shaped path. How far this dust is blown out from the weapon depends on several variables, but an educated guess based on years of post-blast training is that the radioactive material from a dirty bomb would be projected out to a few hundred feet. This is the hot zone and no officer or other public safety personnel should enter it without the appropriate protection, including respirators and radiation suits.

Your Response

Other than providing aid to immediate casualties, the biggest problem you will face during a dirty bomb attack is actually determining that the device is "dirty." In contrast to a chemical weapons attack, which usually has many telltale signs a responder can identify without special gear, dirty bomb attacks are difficult to confirm.

Because an RDD incident visually appears the same as a conventional explosion, the only positive way to determine if an incident involves a radioactive material is through the use of sensitive detection gear in the hands of a trained technician. There simply isn't a "silver bullet" detector that is easy to operate, that is compact, that detects a wide range of materials, and that is inexpensive, so first responders don't have the equipment and training to identify a radiological weapon. Some agencies are issuing radiation "pagers" and that's not a bad idea, but these simple tools are no substitute for more sophisticated hardware.

Until technology catches up with necessity, what I teach my students is to start making changes in their mindset when responding to calls. Even with something as routine as traffic accidents, I instruct them to start paying more attention to the details. You would be surprised how effective a tool this is against terrorism, and as an added bonus, looking past the obvious into the "why" of the event will also help you uncover narcotics and meth labs.

Another way to detect dirty bomb attacks is to use your brain. If you have any reason to believe that the bomb that just went off in your city's most crowded outdoor mall is a WMD, then play it smart. The age of blindly rushing into an incident has passed; create a perimeter and work with other agencies.

Bernard Cohen, professor-emeritus of physics and radiation health at the University of Pittsburgh, says that the key to developing an effective law enforcement response to a radiological attack is to cultivate community resources in advance. "They [law enforcement] should get help from someone who can measure the radiation level and interpret it," he says. "Such people are available at almost any university or any hospital, as well as from industrial users of radioactivity. They should now establish sources for such help. Some states (including Pennsylvania) have already organized procedures for making such people available in each county."

Mass Disruption

Once a dirty bomb attack has been confirmed, the immediate role of law enforcement personnel will be to maintain order. And that's going to be tough because the minute the average American hears the word "radiation," all hell will likely break loose.

This is why the true danger presented by an RDD is its ability to create public fear and economic disruption. Immediately after a radiological attack, hospitals and emergency centers will be flooded with what health care professionals refer to as "worried well." In other words, terrified but healthy people. Law enforcement officers will be needed at these facilities to prevent panicked people from rushing the emergency rooms.

Fear will also play a role in the long-term economic effects of the attack. Just because police, scientists, and government officials say that an area is safe to re-enter that doesn't mean the public will trust our judgment enough to immediately begin resuming normal activities. And real estate values are sure to plummet within miles of the attack area.

It's also going to be very expensive to clean up the attack area. There are several companies that have precisely this type of experience, but they don't work cheap.

In short, it's probably inaccurate to refer to a dirty bomb as a weapon of mass destruction. It's actually a weapon of mass disruption and, while that's not very deadly, it could be economically and emotionally devastating for a community that is attacked.

To this date, no record exists of the use of an RDD as a terrorist weapon, but the availability of components and the relative simplicity of construction make the so-called dirty bomb a very attractive and very likely tool for terrorists. However, with the proper mindset, training, and equipment, law enforcement officers can help minimize the effects of a radiological attack.

Shawn Hughes is a former police officer and bomb technician. He currently serves as lead instructor for the WMD and Explosive Operations programs for Tactical Response Inc. (www.warriormindset.com), and is a frequent contributor to POLICE.