Background radiation equivalent time BRET value corresponding to a dose of radiation is the number of days of average background dose it is equivalent to. It is calculated from the equivalent dose in sieverts by dividing by the average annual background radiation dose in Sv, and multiplying by 365: The definition of the BRET unit is apparently unstandardized, and depends on what value is used for the average annual background radiation dose, which varies greatly across time and location. The 2000 UNSCEAR estimate for worldwide average natural background radiation dose is 2.4 mSv (240 mrem), with a range from 1 to 13 mSv. A
Electromagnetic radiation range, is sometimes called "extreme UV." Ionizing UV is strongly filtered by the Earth's atmosphere). Electromagnetic radiation composed of photons that carry minimum-ionization energy, or more, (which includes the entire spectrum with shorter wavelengths), is therefore termed ionizing radiation. (Many other kinds of ionizing radiation are made of non-EM particles). Electromagnetic-type ionizing radiation extends from the extreme ultraviolet to all higher frequencies and shorter wavelengths, which means that all X-rays and gamma rays qualify. These are capable of the most severe types of molecular damage, which can happen in biology to any type of biomolecule, including mutation and cancer, and