Radiation and Radiological Disasters. Dosimetry is the measurement and calculation of the radiation dose received by matter and tissue resulting from the exposure to indirect and direct ionizing radiation. It is a scientific sub-specialty in the fields of health physics and medical physics that is focused on the calculation and analysis of internal and external dose. Internal dose is calculated from a variety of physiological techniques, whilst external dose is measured with a dosimeter or inferred from other radiation instruments. Dosimetry is routinely applied to occupational radiation workers, where a radiation dose is expected, but regulatory levels must not be exceeded. It is also used where radiation is unexpected, such as in the aftermath of the Chernobyl or Fukishima radiological release incidents, where the public dose is measured and calculated from a variety of indicators such as ambient measurements of radiation and radioactive contamination. Other significant areas are medical dosimetry, where the required treatment dose and any collateral dose is monitored, and in environmental dosimetry, such as radon monitoring in buildings. In all cases the information is used to calculate any likely detrimental health effects. An OSH glossary used in safety and health at work which is, adopted by ILO