Nuclear, Biological, and Chemical Attacks
The dangers in these three cases are similar, but not the same. This page discusses those dangers, and how to avoid them.
The basic problem
A common thread in all these dangers is avoiding very tiny particles that you usually can't see:
- "Avoiding" always means not breathing or swallowing them.
- For some biological and chemical weapons, "avoiding" also means avoiding contact with mucous membranes, your eyes, etc.
- For a very few biological and chemical weapons, "avoiding" also requires avoiding any skin contact at all. Of course, avoiding skin contact is a really good idea in any case; partly because if the stuff has gotten that close, it's going to be hard to be sure you don't wipe your forehead and inhale some as your arm goes by, etc. etc.
- Radioactive materials are the only ones where "avoiding" requires substantial separation. Some nuclear materials can hurt you from a distance, though all can hurt you if inhaled.
I'm not discussing here, the dangers from a nuclear blast itself -- the blast itself, the heat and pressure storm moving at better than hurrucane speeds; the flash; here I'm talking about the danger from radioactive dust, which can spread far and wide.
Radiation comes in many forms. Some of the important issue are described here.
Some occurs only within spitting distance of ground zero, so no protection is needed.
Some can't penetrate clothing or skin, and so is only dangerous if inhaled.
Some can penetrate clothing or skin, but not a lot more, and so staying inside is pretty good protection
Radiation damage to living things is cumulative: the more radiation, the more damage.
Radiation damages cells. If you get hit with enough radiation, enough cells are badly enough damaged that you become sick or die. On the other hand, cells can be repaired and replace -- so if the radiation is spread out over time, the same total dose will do far less harm.
this makes it crucial to monitor your exposure, and keep the total down, and keep the maximum rate you deal with down too.
Radiation and distance
All radiation becomes less dangerous with distance. This is simply because radiation generally travels out from its source in straight lines in all directions. If you wrap yourself around a blob of radioactive stuff, you'll get hit by all the radiation from it. Merely setting it down and standing on one side of it will cause most of the radiation to miss you (the part going down or up, the part going to the sides you're not standing on, etc. the further you step away, the more of the radiation simply misses you. If you're a mile away, only the tiniest fraction of the radiation happens to be aimed straight at you.
If you double your distance from a source of radiation, you cut your exposure to 1/4 as much (2x2 = 4); if you triple your distance, to 1/9 as much (3x3 = 9); and so on.
One very important thing this means: a child who is half your height, is on average twice as close to the ground. That means if you're both walking around in an area with radioactive dust on the ground, the child is getting hit with 4 times the dose you are; and since their body is smaller, that's something more like 10 times as bad. Never let kids walk on the ground in such situations; carry them on your shoulders if they have to be there at all.
Because of the distance factor, a really good place to be is halfway up a high-rise building. Most of the dust will be far away on the ground. A little will be far above on the roof. A tiny bit will be stuck to the outside of the building, but still have to get through what are probably fairly thick, heavy walls (see next section).
Radiation and shielding
The distance factor is actually for the case where there's nothing but distance between you and the radiation source. So technically, it's only accurate if you're out in space with no air (in which case, radiation isnot your only problem). Air blocks a tiny bit of radiation, so doubling your distance actually cuts your exposure by a tiny bit more than 4 times. But air and other gases have so little effect it's not usually worth counting.
Heavy, solid materials are much better at blocking penetrating radiation (the kinds that can go right through skin, clothes, and other materials). The heavier the better.
So getting a lot of weight between you and the radiation is really good. If you're deep underground and the radioactive dust is coating the surface, even the closest particles have to fight through a lot of heavy dirt and rock to get to you.
The good news is that you don't need to go to that extreme. If you're in a basement, the nearest particles probably have to fight through several inches of cement, which is very heavy stuff and will reduce your exposure by a large factor. Particles on the ground further away, have to come down through dirt at an angle and then go through the cement, so even fewer will get through.
The heavier the walls, the better. You can get a pretty good idea of what percentage of radiation will be stopped, by figuring out how much a 1 foot square of the shielding weighs. For example, if you cut a 1' square piece out of a concrete bassement wall 10 inches thick, it weighs about ,
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