By Tom Harris
Dirty bombs are explosives designed to spread dangerous and/or radioactive material over a wide area. When people hear "bomb" and "radioactive" together, their minds jump to nuclear war pretty quickly. But actually, a dirty bomb's main destructive power would probably be panic, not radiation damage. A dirty bomb is more similar in power to an ordinary explosive than it is to the powerful destructive force of a nuclear weapon. But the fear of contamination could be crippling, in the same way that the 2001 anthrax scare in the U.S. terrified many in the American populace, even though very few people were infected.
In concept, Conceptually, a dirty bomb (or radiological dispersion bomb) is a fairly simple device. It uses conventional explosive, such as TNT (trinitrotoluene), packaged with a radioactive material. It's cruder and cheaper than a nuclear bomb, and is much less effective. But it does have the combination of explosive destruction and radiation damage.
High explosives cause damage with rapidly expanding, extremely hot gas. The basic idea of a dirty bomb is to use gas expansion as a means for propelling radioactive material over a wide area, not as a destructive force in its own right. When the explosive goes off, the radioactive material spreads in a sort of dust cloud, carried by wind, that reaches a wider area than the explosion itself.
The long-term damaging force of a dirty bomb would be ionizing radiation from the radioactive material. This type of radiation includes alpha and beta particles, gamma rays and X-rays, has enough energy to knock an orbital electron off an atom. The result is that the balance between an atom's positively charged protons and negatively charged electrons is thrown off, giving the atom a net electrical charge (the atom becomes an ion). This free electron may collide with other atoms to create more ions.
If this happens in a human body, the ion can cause a lot of serious problems, because an ion's electrical charge may lead to abnormal chemical reactions inside cells, and can actually DNA chains. A dirty bomb would boost the radiation level above normal levels, increasing the risk of cancer and radiation sickness to some degree. Most likely, it wouldn't kill many people right away, but it could possibly kill people years down the road.
