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
Particle radiation level of danger posed to humans. Ionization is the process of removing electrons from atoms, leaving two electrically charged particles (an electron and a positively charged ion) behind. The negatively charged electrons and positively charged ions created by ionizing radiation may cause damage in living tissue. Basically, a particle is ionizing if its energy is higher than the ionization energy of a typical substance, i.e., a few eV, and interacts with electrons significantly. According to the International Commission on Non-Ionizing Radiation Protection, electromagnetic radiations from ultraviolet to infrared, to radiofrequency (including microwave) radiation, static and time-varying electric and magnetic fields,