It eases the mind to study the different types of
ionizing radiation, because not all radioactive material act the same. There's not much to learn, and it's quite light reading.
But for those in real hurry:
- Alpha radiation is heavy and does lot of damage, because it interacts strongly with matter. But because it interacts strongly, it does not penetrate so much, and even sheet of paper is enough for a shielding. Not particularly a problem,
Am-242 sources are used in standard smoke alarms. Even that one above your head, I'd wager.
- Beta radiation is slightly more penetrating therefore slightly less dangerous. Plexiglass is the usual shielding. Does high damage at short range, but almost nothing at long range. Concentrations can be high, and this is why ingestion (where the ranges are short) is dangerous.
- Gamma radiation has high penetration, because it interacts very weakly with matter. Shielding is lead walls and good running shoes. But because it interacts weakly, it won't do a lot of damage (in any given separate instance in time). With time, of course.
- Neutron... is a problem. And so on.
When ingested, radioactive particles will be passed just like any food within a day (iodine-131 excluded, of course). This is why they said plutonium is not so dangerous when ingested - it will not accumulate and it's emission is mostly weakly interactive gamma type, plus that the possible amounts for ingestion are extremely small. Not much escaped Fukushima. Of course this implies the best possible dream-land scenario that everything will be all right very very soon (Moshimoshi?!? Chernobyl?!? 25 years today and still going hot? Connecting dots here, people!
) and people don't have to keep on eating that s#it from day to day for decades to come.
Here's a nice page about the radiation situation about 150 km south of Fukushima. It's not a political institute feigning a scientific institute, and it's measurements have been active from the very beginning. You'll notice that there are several types of radiations sources monitored.
So, did I make you look up and look for a smoke alarm? C'mon, be honest!
