It's the word of the moment, the last entry in a horrible dictionary that since last February unfortunately we are learning more and more. Last Sunday the Russian Defense Minister Sergei Shoigu told his counterparts in Britain, the United States, Turkey and France that Ukraine plans to detonate a radioactive dirty bomb on its territory, as part of a plan to discredit Russia.
Although it was quickly dismissed by NATO ministers as a convoluted attempt to break the Western front (or even the staging of a false flag attack to justify another Russian offensive), the prosecution raises the question: what is a bomb dirty and how dangerous is it?

Differences between atomic bomb and dirty bomb
Basically, a dirty bomb is a way to spread radioactive material over a large area. While an atomic bomb triggers a nuclear chain reaction to release huge amounts of energy in an instant and a radioactive fallout as a byproduct, the dirty bomb uses a conventional explosive to disperse a cloud of radioactive dust and contaminate a target area.
A long-standing horror, because the idea wasn't born yesterday. As is often the case, science fiction predicts (or perhaps inspires) the future. Robert A. Heinlein anticipated the dirty bomb in his 1941 science fiction short story "Unsatisfactory solution", in which a US Army general develops a way to sprinkle radioisotope dust over Europe to end World War II.
A few years later, science fiction became a reality.

How they "dirty" the bomb
In the immediate postwar period, the kind nuclear powers have toyed with the idea of enclosing materials such as cobalt and iodine in a nuclear warhead to produce an even more radioactive fallout. From that wickedly ambitious idea, however, we have come to a toxic fallback, but decidedly simpler and cheaper. And this is not good news.
A dirty bomb is so simple to make that anyone could build one. All you need is TNT, appropriate detonating and fusing devices, and a container filled with a dangerous radioisotope: cesium-137 for example.
And radioisotopes are very common in the world. They are used in medicine, industry, science, food storage, agriculture and many other fields. It is one of the reasons governments impose heavy restrictions on the free trade of these isotopes and monitor them closely.
There is not only the risk of military use, but also that of an accident. In Brazil, in 1987, a couple of thieves broke into an abandoned clinic and stole a teletherapy capsule: the thieves were unaware that it contained cesium-137 powder. Result? 249 people contaminated, 20 seriously, and five dead.
Dirty bomb: has it exploded in the past?
There have only been two past attempts to detonate a dirty bomb, in 1995 and 1998 by a Chechen separatist group. Neither, in the end, exploded.
What would happen if it happened? It depends on many factors. The isotopes used, the target, the type of surrounding area and the number of people in the area. However, opinions on the matter are conflicting.
Mini disclaimer: the now almost inextricable intertwining between media and politics makes it difficult to collect sufficiently reliable opinions, so I post them as I found them.
The US Department of Energy, for example, led a series of simulations attack with a dirty bomb and concluded that such a device is largely useless as a weapon intended to achieve a military objective or even to cause death and damage. It would result in the deaths of only a few people (and only from the explosion), and would increase the risk of cancer equal to that of two full-body CT scans.
I frankly have my doubts
The target area of a dirty bomb must be contaminated with radioactive dust: a difficult and costly task that could take billions of euros and decades.
The physical, social, psychological, economic impact of such an event is gigantic, no one dares to minimize it.
The "normalization" of nuclear and radioactive dangers certainly has a strategic function, that of combating panic in the population. In some ways it is right. But for this very reason a dirty bomb must be considered an abominable weapon.

What to do if a dirty bomb explodes?
I can't believe I wrote this paragraph. According to the CDC, Center for Disease Control USA, if you are outdoors when a dirty bomb goes off, the best thing to do is to cover your mouth and nose with a cloth to avoid breathing dust, avoid touching anything and getting inside. a building with intact windows, doors and walls. Once inside, remove the outer garments and close them in a plastic bag: they are no longer usable, they must be disposed of. Finally, wash your hair and body thoroughly with soap and water.
Little Apocalypse lessons, hoping that the reference to the dirty bomb is only part of this absurd chess game that has already cost many, too many lives.