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.
| 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 |