Annual Dose meaning

Annual dose is the total ionising radiation received by a person over a year, used in practice to check compliance with statutory dose limits and to inform risk management in workplaces using radiation. Although “annual dose” itself is a descriptive term, the underlying concepts—dose, effective dose and equivalent dose—and the limits that apply per calendar year are set by legislation: in Great Britain, the Ionising Radiations Regulations 2017 (IRR17); in Northern Ireland, the Ionising Radiations Regulations (Northern Ireland) 2017; and in Ireland, the Safety, Health and Welfare at Work (Ionising Radiation) Regulations 2019, all implementing the Euratom Basic Safety Standards. Annual dose typically comprises external exposure and any committed doses from internal contamination, and is assessed and recorded (for classified persons and, where required, others) by an approved dosimetry service. It is usually considered on a calendar year basis (e.g., 20 mSv for radiation workers; 1 mSv for members of the public), and exceedances trigger mandatory investigations and remedial controls. Usage is broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland. Patient medical exposures are regulated separately: dose limits do not apply to patients, though employers must optimise and justify exposures.