The earth is radioactive as is every person on the planet. In addition the Sun is continually emitting cosmic rays which deliver a dose of radiation. In Australia the mean natural background radiation dose per annum from all of these natural sources has been measured as 1.5 mSv. World-wide the figure is estimated to be 2.4 mSv.



Sources of the natural background radiation
Source mSv per year
External Sources
Cosmic radiation 0.3
Terrestrial radiation 0.6
Body Radioactivity
Potassium-40 0.2
Radon 0.2
Other
radionuclides (Th/U)
0.2
Total 1.5