Sievert (Sv) meaning

In legal practice on ionising radiation, a sievert (Sv) expresses the biological effect of radiation on people and underpins compliance with statutory dose limits, radiation risk assessments and dose records for workers and the public. It is the SI derived unit for equivalent and effective dose and is routinely used across occupational exposure, medical exposure governance, environmental permitting and nuclear site licensing. UK and Irish radiation protection legislation and guidance adopt SI units and state doses in sieverts, usually in millisieverts (mSv) or microsieverts (μSv). Usage is broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland (e.g., under the Ionising Radiations Regulations and national basic safety standards regulations). 1 Sv equals 1 joule per kilogram and is equivalent to 100 rem. Effective dose (Sv) is calculated from the absorbed dose measured in grays (Gy), adjusted by radiation and tissue weighting factors to reflect the type of radiation and the organ or tissue exposed. Named after Rolf Sievert. For comparison: activity (how much radiation is emitted) is measured in becquerels (Bq), and absorbed dose (energy deposited) is measured in grays (Gy).