XDA

Ex-Russian spy Alexander Litvenenko has died from his recent poisoning in London, probably by Polonium 210, a radioactive substance. I think you can see that he was dying in the photo to the left.

Radioactivity means generally that three things are put off by the isotope of a heavy element, which is decaying on the atomic level--alpha and beta particles and gamma waves. The alpha particle is relatively slow and heavy with two protons and two neutrons. It has extremely wimpy penetrating power--it would be stopped by paper or even by the layer of dead cells on top of our skin. But inside a cell a beta particle ionizes and causes thereby damage to the cell (and to the DNA). If you can keep from ingesting something emitting alpha particles, either through eating or drinking it, breathing it in or having it enter a wound, there is little to fear from alpha particles. However, since Mr. Litvenenko ingested Polonium 210, the alpha particles did a lot of cellular damage.

Beta particles are pretty much electrons and are fast and light and have some penetrating power. Aluminum foil or better, or even a plastic like perspex stops the particles and even heavy cloth is an effective shield. Again, ingesting what emits beta particles makes them deadly inside. The particles cause little ionizing but people exposed to beta particles develop on their skin what is called a beta burn, which is like a bad sunburn on steroids.

Gamma radiation is not a particle so it has no mass or a charge. It is the top (highest frequency) of the electro-magnetic spectrum (which includes radio waves and visible light) and it does not directly ionize the cells it hits but causes changes in the cell which in turn can cause ionization and the damage of the particles. Several inches of lead or several feet of concrete can stop gamma radiation. The only way to escape it in the open air is to get out of the area, as quick as you can.

There really is no cure for radiation poisoning. The treatment is merely to react to signs and symptoms with palliation and hope the body can repair itself. Anti-radiation medication merely helps the thyroid not develop cancer. Sometimes a bone marrow transplant can save a person after a usually deadly dose of radiation. However, double the usually deadly dose (measured in rads or seiverts) and death will occur. Increase the usually deadly dose by a factor of ten and debilitation occurs almost instantly and death within a few hours.

It's not a pleasant way to go.

However, if a dirty bomb were to go off, put on clothes (with aluminum foil underneath if you're home) and a Michael Jackson like mask, maybe some goggles and move quickly away from the detonation point (upwind if that's possible) and you should be OK.

To avoid Mr. Litvenenko's fate one could avoid sushi bars or, better yet, pissing off Vladimir Putin.