If I may..
For anyone still wondering, the way radiation units works is: you've got three kinds of units. One for the amount of atomic activity (ie atoms going pop per second - "
curies" or "
becquerels"), another for the amount of energy transfered to a set amount of mass (eg joules per kilogram - "
rads" or "
grays"), and a third one measuring the effects for irradiation of your whole body (rads or grays multiplied by a "Q" number = "
rems" or "
sieverts"; "Q" depends on the type of radiation e.g. gamma, alpha, or neutron radiation).
Radiation is like heat (UV rays and visible light are radiation), it's everywhere and only trouble (cell damage stronger/faster than body can replace them) once you're exposed to more than a certain amount... like sunburn. EG bananas often set off radiation detectors e.g. at customs checks. One banana's worth of radiation is more than the amount of radiation detected in a glass of local milk after Three Mile Island.
http://en.wikipedia.org/wiki/Banana_equivalent_dose1 Sievert = 100 rems.
1 "micro sievert" uSv = 1 millionth of a Sievert.
1 "milli rem" mrem= 1 thousandth of a rem.
1 Sv = 1,000 mSv = 1,000,000 uSv etc
http://en.wikipedia.org/wiki/Radiation_poisoning#Exposure_levelsLiving near a nuclear power station = less than 0.01 mSv/year
Eating 3 bananas/day = 0.1 mSv/year
Cosmic radiation (from sky) at sea level = 0.24 mSv/year
Terrestrial radiation (from ground) = 0.28 mSv/year
Natural radiation in the human body = 0.40 mSv/year
Average American's natural radiation exposure: 3.1 mSv/year
Radon in the average US home = 2 mSv/year
Average American's total radiation exposure: 6.2 mSv/year
Smoking 1.5 packs/day = 13 mSv/year
Note these are in Sieverts
per year - the difference from plain Sieverts is as between power and energy .
http://en.wikipedia.org/wiki/Kilowatt_hour#Confusion_of_kilowatt_hours_and_kilowatts_per_hour
