Radioactive materials occur naturally and, as a result, everyone is exposed to a low-level of radiation every day. This exposure comes from a mixture of natural and man-made sources.
The actual amount of radiation that a person is exposed to depends on where they live, what job they do and many other things.
Scientists must always take into consideration the amount of background radiation when working or experimenting with radioactive sources and discount it from their results.
The Sievert (Sv) is the unit to measure radiation dose and is the amount of damage that would be caused by the absorption of 1 joule of energy in each kilogram of body mass.
Typically, absorption is less than 1 Sv, so milliSieverts (mSv) are often used instead. 1,000 mSv = 1 Sv.
Some example doses are shown below:
|Eating a banana that contains radioactive potassium||0.000000098 Sv||0.000098 mSv|
|Exposure for cabin crew on airliners (per year)||0.0016 Sv||1.6 mSv|
|6 months on the International Space station||0.08 Sv||80 mSv|
|Highest dose to a worker during Fukushima disaster||0.67 Sv||670 mSv|
|Typical fatal dose||10 Sv||10,000 mSv|