Overview
EN ISO 20785-1:2020 - "Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 1: Conceptual basis for measurements" - establishes the conceptual framework for determining ambient dose equivalent (H(10))* and for the calibration of instruments used to evaluate cosmic radiation exposure in civilian aircraft. Published as an ISO standard and adopted by CEN, this third edition (2020) updates terms, references and guidance for traceable, uncertainty‑aware measurements of the complex atmospheric radiation field at flight altitudes.
Key topics and requirements
- Scope and purpose: Defines the conceptual basis for measuring ambient dose equivalent to validate calculated effective doses for aircrew and to support instrument calibration.
- Terms and quantities: Standardizes terminology and units used for atmospheric radiation and dosimetry, ensuring consistent interpretation of H*(10) and related operational quantities.
- Atmospheric radiation field: Describes characteristics of cosmic radiation at flight altitudes (primary galactic and solar particles and secondary radiation produced in atmosphere and aircraft).
- Calibration considerations: Guidance on calibration approaches, simulated aircraft fields, traceability, and accounting for differences between calibration fields and the full atmospheric field.
- Conversion coefficients: Discusses use of conversion coefficients to relate particle fluence to operational dose quantities.
- Dosimetric devices: Covers both active and passive detectors, including:
- Active devices for whole-field, low‑LET (non-neutron) and high‑LET/neutron components
- Passive detectors such as etched track detectors, fission foil detectors, bubble detectors, thermoluminescent (TLD) and photoluminescent detectors
- Uncertainty and validation: Emphasizes traceability, representative calibration, and inclusion of uncertainties when validating calculation methods with measurements.
- Annexes: Includes representative particle fluence/energy distributions for flight altitudes under different solar and geomagnetic conditions.
Applications and users
This standard is intended for professionals and organizations involved in aviation radiation protection and dosimetry, including:
- Airlines and crew safety managers assessing occupational exposure and complying with regulatory limits (e.g., EU requirements for crew receiving >1 mSv/year).
- Radiation protection authorities and regulators implementing national safety standards and inspections.
- Calibration laboratories and instrument manufacturers establishing calibration procedures and traceability for airborne dosimeters.
- Radiation dosimetrists and researchers validating computational dose models and comparing measured ambient dose equivalent rates with calculated values.
- Aviation medical and occupational health teams using dose estimates for roster planning and pregnancy protection.
Related standards and guidance
- ISO 20785 series (other parts) - measurement and assessment methods for airborne cosmic radiation (see ISO website for full list).
- ICRP publications and EU/IAEA Basic Safety Standards - provide the regulatory and protection context referred to in the standard.
Keywords: EN ISO 20785-1:2020, cosmic radiation dosimetry, ambient dose equivalent, aircraft dosimetry, calibration, aircrew exposure, dosimetric devices, radiation protection.
