Dirty Bomb

Conventional explosive device outfitted with radioactive material. A dirty bomb is not a nuclear bomb, because its detonation does not involve the complex process of nuclear fission. Its discharge mechanism is based on a nonnuclear explosive material such as dynamite. However, instead of spewing out metal shrapnel subsequent to the blast, a dirty bomb releases radioactive material in the form of a gas or a powder.

As opposed to nuclear bombs, dirty bombs (also known as radiological dispersal devices, or RDDs) are not likely to cause large numbers of human deaths. According to most scientists, the main danger associated with the use of a dirty bomb is not radioactive contamination but rather the panic the bomb produces among its intended targets. In addition, cleaning up a radioactively infected area is extremely costly, potentially causing serious economic problems. Because of the primarily psychological effects of a dirty bomb, terrorism experts do not generally refer to an RDD as a weapon of mass destruction but rather as a weapon of mass disruption.

Acquiring the Radioactive Materials

The expertise necessary to build a dirty bomb is the same as that required for the assembly of a conventional explosive device. The real difficulty behind the crafting of an RDD is acquiring and handling the radioactive material—the one thing that earns the bomb the adjective dirty. As a rule, the higher the quality of the radioactive material (and hence, the more human fatalities it is likely to cause), the harder it is to obtain on the international market.

There is no scarcity of nuclear material in the world; it is used extensively in medicine, agriculture, and industry. However, the potency of a radioactive source used in, for example, a cancer therapy device is limited and does not make for a powerful dirty bomb. The truly damaging radioactive materials are those that have been manipulated as part of a nuclear program, be it industrial or military. Although such material is generally well guarded throughout the world, terrorism experts point to the region of the former Soviet Union, where weaponry-related radioactive sources have been found lying around unprotected in the mountains.

Numerous governments (including those of Russia and the United States) are currently taking steps toward keeping all radioactive materials out of the hands of terrorist organizations. No dirty bombs have been detonated yet, but the terrorist network of al-Qaeda is widely believed to be attempting to build an RDD.

Effects of a Dirty-Bomb Blast

The number of human deaths that a dirty bomb could cause depends on the bomb's sophistication (that is, the quality of the radioactive material), wind conditions in the area of detonation, and the rapidity with which that area is evacuated by authorities. Experts estimate that the death toll in the event of a dirty-bomb blast would not be higher than a few dozen fatalities, most of them caused by the conventional explosion itself and not by radioactivity.

However, the specter of an unseen, silent radioactive killer is likely to cause panic among people in the vicinity of the blast. That panic might even cause more deaths (from trampling, car accidents, and so on) than the detonation itself. In the event of a RDD explosion, U.S. authorities will advise people to minimize their time of exposure to the area's atmosphere, go as far away from the blast site as possible, and move away in such a manner as to place several buildings between them and the bomb location.

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