Idril wrote:I think some of you are missing the point.
Yes, we are exposed to radiation everyday from various objects, but what is worrisome is that the possible exposure to gamma radiation.
Gamma waves can only be stopped with several feet of concrete, whereas "everyday radiation" can be stopped by your skin (even β-rays from microwaves etc are generally harmless).
I wouldn't make light of alpha and beta particles just because they can be easily shielded. Should you happen to ingest something that emits the particles, you can still experience internal damage. Noted that microwaves are generally harmless, though I wouldn't suggest monkeying around on an active high powered telecommunications dish. Just imagine you "cooking" yourself, I'm sure that is bound to tick off a few cells in your body.
Also, the background radiation (or as you call it "everyday radiation") I mentioned earlier specifically relates to the exposure of ionizing radiation, which are measured in sieverts (typically measured in milli-, micro-, and nano-sieverts). This measurement is what I discussed earlier as to what governments around the world utilize to determine acceptable levels of exposure.
In most countries, the current maximum permissible dose to radiation workers is 20 mSv (millisievert) per year averaged over five years, with a maximum of 50 mSv in any one year. This is over and above background exposure, and excludes medical exposure.
(From wiki: Sievert
Like I said, we are exposed to harmful radiation every day. The body is able to cope with small amounts of exposure over a period of time. Now this doesn't mean that the body isn't being damaged, but the body does have an incredible ability to repair the small amounts of damage done over time.
If you look at this radiation map of Japan
. You can easily calculate your annual exposure to see how close you are to the limit.
Assuming you were near the upper 1,600 nSv/h on the map it would come out to (1600 * 0.000001) = (0.0016 mSv/h * 24 (hours)) * 365 days = 14.016 mSv/year which is within the 20 mSv/year allotment though I wouldn't suggest going anywhere near that limit.
Here are some annual values referenced in the Sievert wiki article for comparison:
-- Average individual background radiation dose: 2 mSv/year; 1.5 mSv/year for Australians, 3.0 mSv/year for Americans
-- New York-Tokyo flights for airline crew: 9 mSv/year
For a little perspective, a one-time exposure from a chest CT scan is 6–18 mSv.
Namisuke wrote:Too often people compare high radiation levels to eating bananas. Yes, bananas have some natural radiation, but it should in no way be used to measure radiation in Fukushima. This whole banana trend that came out this year personally drives me nuts because it confuses people who don't know much about radiation and makes light of something that can be really serious if strange comparisons are used.
You shouldn't get your knickers in a twist over something like that, it is a valid comparison as there is enough radioactivity present to allow the comparison to be drawn. It doesn't make light of anything as it is just a function for reference and conversion. Also, the banana trend as you call it, started back in 1995. Granted, people need to understand that potassium-40 is a source of non-ionizing radiation.
According to the US Environmental Protection Agency (EPA), the conversion factor (CEDE) is 5.02 nanosieverts over 50 years for each becquerel of isotopically pure potassium-40 ingested by an average adult. Using this factor, one banana equivalent dose comes out as about 5.02 nSv/Bq × 31 Bq/g × 0.5 g ≈ 78 nanosieverts = 0.078 μSv. In informal publications one often sees this estimate rounded up to 0.1 μSv. ~ Although small in environmental and medical terms, the radioactivity of a few bananas is sufficient to trigger radiation sensors used to detect possible smuggling of nuclear material at U.S. ports.
(From wiki: Banana Equivalent Dose
Namisuke wrote:You won't need a radiation detector in Japan. Radiation levels are posted online from multiple sources. It is important to take risks seriously, but also to not get to wild and imaginative about it. Taking a radiation detector everywhere would be like wearing a hard hat all the time. That's not too realistic.
I'm not sure how you can simply declare what is realistic for people. If someone wants to wear a personal sized radiation meter (they have small pendant sized ones that sound an alarm if the dose per hour gets too high), that is their choice to have it. Irradiated debris was potentially flung from the resulting exterior explosions around the reactor with no way of knowing how far the bits of debris traveled. Should you happen to cross a piece of metal that absorbed enough radiation and stayed around it long enough, you can put yourself at risk. Again, the chances of coming across a significantly irradiated piece of debris is slim to none, but if you find yourself in an environment that has an elevated chance of it occurring, it doesn't hurt to be a bit more prepared.
TL;DR: @Idril You seemed to have labeled background radiation as merely just exposure to alpha and beta particles (which isn't true), though the majority of ionizing radiation from space is broken down by the atmosphere. It's not just gamma rays to worry about, but all manner of ionized particles. @Namisuke It is definitely important to find good sources of information, but is never a substitute if you wish to conduct your own research. I prefer not to wait for some "official" body to report on what is safe or not safe. It is always best to determine things for yourself, so long as you are confident you can learn how to reach the conclusion through the basic scientific principles. Also, be nice to banana's they are delicious and nutritious.
Good god, this was a long post... -_-
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