What is a "dirty bomb"?

A "dirty bomb," also known as a radiological weapon, is a conventional explosive such as dynamite that has been packaged with radioactive material, which scatters when the bomb goes off. A dirty bomb kills or injures through the initial blast of the conventional explosive and by airborne radiation and contamination -- hence the term "dirty." Such bombs could be miniature devices or as big as a truck bomb.

How much expertise does it take to make a dirty bomb?

Not much more than it takes to make a conventional bomb. No special assembly is required; the regular explosive would simply disperse the radioactive material packed into the bomb. The hard part is acquiring the radioactive material, not building the bomb. The Washington Post reported in March 2002 that the Bush administration's consensus view was that Osama bin Laden's al-Qaeda terrorist network probably had such frequently stolen radioactive contaminants as strontium 90 and cesium 137, which could be used to make a dirty bomb.

Indeed, the relative ease of constructing such weapons makes them a particularly worrisome threat, counterterrorism experts say. Even so, expertise matters. Not all dirty bombs are equally dangerous: the cruder the weapon, the less damage caused. We don't know if terrorists could handle and detonate high-grade radioactive material without fatally injuring themselves first.

Is a dirty bomb a nuclear weapon?

No. Nuclear weapons involve a complex nuclear-fission reaction and are thousands of times more devastating.

Is a dirty bomb a weapon of mass destruction?

Yes, but perhaps more in its capacity to cause terror and disruption than its ability to inflict heavy casualties, experts say. Depending on the sophistication of the bomb, wind conditions, and the speed with which the area of the attack was evacuated, the number of deaths and injuries from a dirty bomb explosion might not be substantially greater than from a conventional bomb explosion. But panic over radioactivity and evacuation measures could snarl a city. Moreover, the area struck would be off-limits for at least several months during cleanup efforts, which could paralyze a local economy and reinforce public fears about being near a radioactive area.

Has a dirty bomb ever been used?

No. According to a United Nations report, Iraq tested a one-ton radiological bomb in 1987 but gave up on the idea because the radiation levels it generated were not deadly enough.

Which radioactive materials could be used to make a dirty bomb?

Many types of radioactive materials with military, industrial, or medical applications could be used in a dirty bomb. Weapons-grade plutonium or uranium, as well as freshly spent nuclear fuel, would be the most deadly but are also the hardest to obtain and handle. Medical supplies such as radium or certain cesium isotopes, used in cancer treatments and X-ray machines, could be used, although they generally would be less dangerous. As little as a measuring cup's worth of radioactive material would be needed, but experts say that such small amounts would be unlikely to cause severe harm, especially if scattered over a wide area.

Do terrorists have such radioactive substances?

It is hard to say, but some experts think they might. Many experts worry that determined terrorists could acquire them; Abu Zubaydah, the captured al-Qaeda operations chief, told U.S. officials in April 2002 that the bin Laden network was trying hard to build dirty bombs. The International Atomic Energy Agency, a Vienna-based division of the United Nations, has documented almost 400 cases of trafficking in nuclear or radiological materials since 1993. Many such supplies are subject to few controls or are poorly guarded, particularly in the former Soviet Union; in May 2002 the U.S. and Russia agreed to form a joint task force to improve security for materials that could be used in dirty bombs. Reports also have cited weak protection of spent fuel at U.S. nuclear facilities, and other experts worry about the security of nuclear facilities in Pakistan, India, and other developing countries.

How widespread would the damage from a dirty bomb be?

It depends, experts say, on the type and amount of radioactive and conventional explosive material in the bomb, as well as on such factors as wind, the size of the buildings in the area attacked, and the ballistics at detonation. In one particularly grim scenario -- the detonation of a truck bomb containing 100 pounds of one-year-old spent nuclear fuel -- the actual acute physical health threat might be confined to a radius of a few city blocks, plus areas under a narrow wind-borne cloud, according to Bruce Blair of the Center for Defense Information. But in the aftermath of September 11, U.S. scientists are conducting more detailed evaluations; they emphasize that such calculations are extremely complicated.

How many people would be killed or injured by a dirty bomb?

People in the immediate vicinity would likely die from the force of the conventional explosion itself. Some survivors of the blast might die of radiation poisoning in the weeks afterward. Those farther away from the explosion might suffer radiation sickness in the days and weeks afterward but recover. Over time, risks of cancer in the affected area would rise, but perhaps only slightly, experts say. According to the atomic experts Richard Garwin and Georges Charpak, the explosion of a dirty bomb containing one kilogram of plutonium in the center of Munich, Germany, could ultimately lead to 120 cancer cases attributable to the blast.

Would the attacked area ever be usable again?

Probably. A relatively crude device set off in a large building might require at least several months of intense cleanup efforts, costing perhaps tens of millions of dollars -- somewhat like the fumigation of the Hart Senate Office Building after the 2001 anthrax-letter attacks. But public fear would still linger, as might radioactive hot spots. It could be hard to assess exactly where and when the radioactivity had returned to safe levels, experts say.

What could be done to stop a plot to use a dirty bomb?

One key, experts say, would be monitoring suspicious cargo at borders, using radiation-detection equipment. The more threatening the substance, the easier it would be to spot it, scientists note. In Times Square during New Year's Eve 2001, the New York Police Department used Geiger counters to detect potential dirty bombs. Other critical defense measures are intelligence-gathering about possible strikes and stepped-up nonproliferation and security efforts to prevent dangerous radioactive materials from falling into terrorists' hands.

Does the U.S. government have a plan to respond to a dirty bomb explosion?

The Federal Emergency Radiological Response Plan, drawn up in 1996 and rehearsed regularly, covers many scenarios related to the release of radiation. The Federal Emergency Management Agency would coordinate the response by several civilian and military entities. After dealing with the initial blast, the top priorities would be the treatment of radiation sickness, the containment and monitoring of radioactive fallout, evacuation, and decontamination.

What should I do if I'm in the vicinity of a dirty bomb explosion?

There would probably be no immediate way for the public to distinguish a dirty bomb explosion from a regular explosion. Experts advise people to stay inside or get inside, and then listen to the radio or television for further information.

From TerrorismAnswers.com