EN ISO 20785-3:2023

Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at aviation altitudes (ISO 20785-3:2023)

This document gives the basis for the measurement of ambient dose equivalent at flight altitudes for the evaluation of the exposures to cosmic radiation in civilian aircraft.

Dosimetrie zu Expositionen durch kosmische Strahlung in Zivilluftfahrzeugen - Teil 3: Messungen auf Flughöhen (ISO 20785-3:2023)

Dieses Dokument dient als Grundlage für die Messung der Umgebungs-Äquivalentdosis in Flughöhen zur Bestimmung der Expositionen gegenüber kosmischer Strahlung in zivilen Luftfahrzeugen.

Dosimétrie pour les expositions au rayonnement cosmique à bord d'un avion civil - Partie 3: Mesurages à bord d'avions (ISO 20785-3:2023)

Le présent document fournit les principes de base permettant de mesurer l’équivalent de dose ambiant aux altitudes de vol pour l’évaluation de l’exposition au rayonnement cosmique à bord d’un avion.

Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu - 3. del: Meritve na višini letenja (ISO 20785-3:2023)

Standard ISO 20785-3:2015 se v celoti ali v delih normativno sklicuje na naslednje dokumente, ki so nepogrešljivi pri njegovi uporabi. Pri datiranih sklicevanjih se uporablja samo navedena izdaja. Pri nedatiranih sklicevanjih se uporablja zadnja izdaja referenčnega dokumenta (vključno z morebitnimi dopolnili).

General Information

• Status: Published
• Publication Date: 20-Jun-2023
• ICS: 13.280 - Radiation protection
• ICS: 17.240 - Radiation measurements
• ICS: 49.020 - Aircraft and space vehicles in general
• Technical Committee: CEN/TC 430 - Nuclear energy, nuclear technologies, and radiological protection
• Drafting Committee: CEN/TC 430 - Nuclear energy, nuclear technologies, and radiological protection
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 21-Jun-2023
• Completion Date: 21-Jun-2023
• Ref Project: SIST EN ISO 20785-3:2023 - Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at aviation altitudes (ISO 20785-3:2023)

Relations

• Replaces: EN ISO 20785-3:2017 - Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at aviation altitudes (ISO 20785-3:2015)
• Effective Date: 19-Jan-2023

Overview

EN ISO 20785-3:2023 - Dosimetry for exposures to cosmic radiation in civilian aircraft, Part 3: Measurements at aviation altitudes provides the basis for measuring ambient dose equivalent (H(10))* at flight altitudes. The standard supports validation of calculated effective doses to aircrew and passengers by defining measurement principles, instrument requirements, and environmental and operational considerations relevant to cosmic radiation dosimetry in civilian aircraft.

Key topics and requirements

• Scope and objective
  • Measurement of ambient dose equivalent at flight altitudes to evaluate exposures to cosmic radiation in civilian aircraft.
• Operational quantity
  • Use of ambient dose equivalent H(10)* as the operational quantity for in-flight measurements and validation of dose assessment models.
• Parameters determining dose rate
  • Barometric altitude, geographic coordinates and solar activity are identified as primary drivers of cosmic dose rates.
• Instrument selection and characterization
  • Guidance on selecting appropriate active (real-time) and passive detectors, and on characterizing instrument response and applying correction factors.
• In-flight practical considerations
  • Factors affecting measurements inside aircraft: cabin pressure, temperature, humidity, vibrations and shocks, electromagnetic interference, power supply for active devices, and security X‑ray scanning for passive dosimeters.
• Background, corrections and uncertainties
  • Procedures for background subtraction, application of correction factors and estimation of measurement uncertainties.
• Supporting data
  • Annex A provides representative particle fluence energy distributions for flight-altitude cosmic fields under different solar and geomagnetic conditions.

Practical applications and users

EN ISO 20785-3:2023 is intended for organizations and professionals involved in monitoring and managing aviation radiation exposure:

• Airlines and crew rostering teams - to validate dose calculations used for occupational exposure management (including the EU requirement to account for crew likely to exceed 1 mSv/year).
• Radiation protection officers and regulatory bodies - for compliance, audit and guidance on in‑flight measurement practice.
• Dosimetry laboratories and instrument manufacturers - for instrument testing, calibration, and characterization at aviation altitudes.
• Researchers and modelers - to validate atmospheric/cosmic radiation transport models and ground-to-flight dose conversion factors.
• Civil aviation safety and health authorities - to integrate measurement-based data into policy and worker protection (including pregnancy dose considerations).

Related standards and guidance

• EN ISO 20785 series (other parts) for broader dosimetry guidance.
• ICRP and ICRU recommendations and the EU Basic Safety Standards (BSS) Directive, which provide the regulatory and protection context referenced by this standard.

Keywords: EN ISO 20785-3:2023, dosimetry, cosmic radiation, aviation altitudes, ambient dose equivalent, aircrew exposure, in‑flight measurements, flight altitudes measurements.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2023
Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem
prometu - 3. del: Meritve na višini letenja (ISO 20785-3:2023)
Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at
aviation altitudes (ISO 20785-3:2023)
Dosimetrie zu Expositionen durch kosmische Strahlung in Zivilluftfahrzeugen - Teil 3:
Messungen auf Flughöhen (ISO 20785-3:2023)
Dosimétrie pour les expositions au rayonnement cosmique à bord d'un avion civil - Partie
3: Mesurages à bord d'avions (ISO 20785-3:2023)
Ta slovenski standard je istoveten z: EN ISO 20785-3:2023
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20785-3
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2023
EUROPÄISCHE NORM
ICS 13.280; 17.240; 49.020 Supersedes EN ISO 20785-3:2017
English Version
Dosimetry for exposures to cosmic radiation in civilian
aircraft - Part 3: Measurements at aviation altitudes (ISO
20785-3:2023)
Dosimétrie pour les expositions au rayonnement Dosimetrie zu Expositionen durch kosmische
cosmique à bord d'un avion civil - Partie 3: Mesurages Strahlung in Zivilluftfahrzeugen - Teil 3: Messungen auf
à bord d'avions (ISO 20785-3:2023) Flughöhen (ISO 20785-3:2023)
This European Standard was approved by CEN on 10 June 2023.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20785-3:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 20785-3:2023) has been prepared by Technical Committee ISO/TC 85 "Nuclear
energy, nuclear technologies, and radiological protection" in collaboration with Technical Committee
CEN/TC 430 “Nuclear energy, nuclear technologies, and radiological protection” the secretariat of
which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2023, and conflicting national standards
shall be withdrawn at the latest by December 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 20785-3:2017.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 20785-3:2023 has been approved by CEN as EN ISO 20785-3:2023 without any
modification.
INTERNATIONAL ISO
STANDARD 20785-3
Second edition
2023-06
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 3:
Measurements at aviation altitudes
Dosimétrie pour les expositions au rayonnement cosmique à bord
d'un avion civil —
Partie 3: Mesurages à bord d'avions
Reference number
ISO 20785-3:2023(E)
ISO 20785-3:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 20785-3:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantities and units . 1
3.2 Atmospheric radiation field . 4
4 General considerations .5
4.1 General description of the cosmic radiation field in the atmosphere . 5
4.2 General considerations concerning the measurements . 7
4.2.1 General . 7
4.2.2 Selection of appropriate instruments . 7
4.2.3 Characterization of the responses of the instruments . 7
4.2.4 Measurements inside an aircraft . 7
4.2.5 Application of appropriate correction factors . 8
4.3 Safety and regulatory requirements for in-flight measurements . 8
5 Measurement at aviation altitude .8
5.1 Parameters determining the dose rate . 8
5.1.1 Barometric altitude . 8
5.1.2 Geographic coordinates . 8
5.1.3 Solar activity . 9
5.2 Possible influence quantities . 9
5.2.1 General . 9
5.2.2 Cabin air pressure . 9
5.2.3 Cabin air temperature . 9
5.2.4 Cabin air humidity . 9
5.3 Specific considerations for active instruments . 9
5.3.1 Power supply . . 9
5.3.2 Vibrations and shocks . 10
5.3.3 Electromagnetic interferences from the aircraft . 10
5.4 Specific considerations for passive measurements . 10
5.4.1 Security X-ray scanning . 10
5.4.2 Background subtraction . 10
6 Uncertainties .10
Annex A (informative) Representative particle fluence energy distributions for the cosmic
radiation field at flight altitudes for solar minimum and maximum conditions and
for minimum and maximum vertical cut-off rigidity .11
Bibliography .17
iii
ISO 20785-3:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technology, and
radiological protection, Subcommittee SC 2, Radiological protection, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 430, nuclear energy, nuclear
technologies and radiological protection, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 20785-3:2015), which has been
technically revised.
The main changes are as follows:
— revision of the definitions of the terms;
— updated references.
A list of all parts in the ISO 20785 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO 20785-3:2023(E)
Introduction
Aircraft crews are exposed to elevated levels of cosmic radiation of galactic and solar origin
and secondary radiation produced in the atmosphere, the aircraft structure and its contents.
Following recommendations of the International Commission on Radiological Protection (ICRP)
[3] [4]
in Publication 60 , confirmed by Publication 103 , the European Union (EU) introduced a revised
[5]
Basic Safety Standards Directive which included exposure to natural sources of ionizing radiation,
including cosmic radiation, as occupational exposure. The Directive requires account to be taken of the
exposure of aircraft crew liable to receive more than 1 mSv per year. It then identifies the following four
protection measures:
a) to assess the exposure of the crew concerned;
b) to take into account the assessed exposure when organizing working schedules with a view to
reducing the doses of highly exposed crew;
c) to inform the workers concerned of the health risks their work involves;
d) to apply the same special protection during pregnancy to female crew in respect of the ‘child to be
born’ as to other female workers; after declaration of pregnancy, to ensure that the additional dose
to the embryo/foetus would not exceed 1 mSv.
The EU Council Directive has to be incorporated into laws and regulations of EU Member States and has
to be included in the aviation safety standards and procedures of the Joint Aviation Authorities and the
European Air Safety Agency. Other countries such as Canada and Japan have issued advisories to their
airline industries to manage aircraft crew exposure. ICRP has recommended a graded approach for
radiological protection of flyers by setting three groups: aircraft crews, frequent flyers, and occasional
flyers and encourages frequent flyers to perform self-assessment of their doses from cosmic radiation
[6]
so that they could consider adjustment of their flight frequency as necessary .
For regulatory and legislative purposes, the radiation protection quantities of interest are equivalent
dose (to the foetus) and effective dose. The cosmic radiation exposure of the body is essentially uniform
and the maternal abdomen provides no effective shielding to the foetus. As a result, the magnitude
of equivalent dose to the foetus can be put equal to that of the effective dose received by the mother.
Doses on board aircraft are generally predictable, and events comparable to unplanned exposure in
other radiological workplaces cannot normally occur (with the rare exceptions of extremely intense
and energetic solar particle events). Personal dosemeters for routine use are not considered necessary.
The preferred approach for the assessment of doses of aircraft crew, where necessary, is to calculate
directly effective dose rate, as a function of geographic location, altitude and solar cycle phase, and
to fold these values with flight and staff roster information to obtain estimates of effective doses for
individuals. This approach is supported by guidance from the European Commission, the ICRP in
[7] [8]
Publication 75 and the ICRU in Report 84 .
The role of calculations in this procedure is unique in routine radiation protection and it is widely
accepted that the calculated doses should be validated by measurement. As effective dose is not directly
measurable, the operational quantity of interest is ambient dose equivalent, H*(10). Although the new
[9]
recommendations on operational quantities have recently been published by ICRU , there would be
a delay before being introduced into future ISO and IEC standards. As indicated in particular in ICRU
Report 84, the ambient dose equivalent is considered to be a conservative estimator of effective dose
if isotropic or superior isotropic irradiation can be assumed. In order to validate the assessed doses
obtained in terms of effective dose, calculations can be made of ambient dose equivalent rates or route
doses in terms of ambient dose equivalent, and values of this quantity determined by measurements
traceable to national standards. The validation of calculations of ambient dose equivalent for a
particular calculation method may be taken as a validation of the calculation of effective dose by
the same computer code, but this step in the process may need to be confirmed. The alternative is to
establish, a priori, that the operational quantity ambient dose equivalent is a good estimator of effective
dose and equivalent dose to the foetus for the radiation fields being considered, in the same way that
the use of the operational quantity personal dose equivalent is justified for the estimation of effective
v
ISO 20785-3:2023(E)
dose for radiation workers. Ambient dose equivalent rate as a function of geographic location, altitude
and solar cycle phase is then calculated and folded with flight and staff roster information.
The radiation field in aircraft at altitude is complex, with many types of ionizing radiation present, with
energies ranging up to many GeV. The determination of ambient dose equivalent for such a complex
radiation field is difficult. In many cases, the methods used for the determination of ambient dose
equivalent in aircraft are similar to those used at high-energy accelerators in research laboratories.
Therefore, it is possible to recommend dosimetric methods and methods for the calibration of dosimetric
devices, as well as the techniques for maintaining the traceability of dosimetric measurements to
national standards. Dosimetric measurements made to evaluate ambient dose equivalent have to be
performed using accurate and reliable methods that ensure the quality of readings provided to workers
and regulatory authorities. This document gives procedures for the characterization of the response of
instruments for the determination of ambient dose equivalent in aircraft.
Requirements for the determination and recording of the cosmic radiation exposure of aircraft crew have
been introduced into the national legislation of EU Member States and other countries. Harmonization
of methods used for determining ambient dose equivalent and for calibrating instruments is desirable
to ensure the compatibility of measurements performed with such instruments.
This document is intended for the use of primary and secondary calibration laboratories for ionizing
radiation, by radiation protection personnel employed by governmental agencies, and by industrial
corporations concerned with the determination of ambient dose equivalent for aircraft crew.
vi
INTERNATIONAL STANDARD ISO 20785-3:2023(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 3:
Measurements at aviation altitudes
1 Scope
This document gives the basis for the measurement of ambient dose equivalent at flight altitudes for
the evaluation of the exposures to cosmic radiation in civilian aircraft.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 98-1, Uncertainty of measurement — Part 1: Introduction to the expression of uncertainty
in measurement
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 80000-10 for consistent
uses of quantities and units, and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Quantities and units
3.1.1
particle fluence
fluence
Φ
differential quotient of N with respect to a, where N is the number of particles incident on a sphere of
cross-sectional area a:
dN
Φ =
da
-2 -2
Note 1 to entry: The unit of the fluence is m , a frequently used unit is cm .
ISO 20785-3:2023(E)
Note 2 to entry: The energy distribution of the particle fluence, Φ , is the quotient dΦ by dE, where dΦ is the fluence
E
of particles of energy between E and E + dE. There is an analogous definition for the direction distribution, Φ , of
Ω
the particle fluence. The complete representation of the double differential particle fluence can be written (with
arguments) Φ (E,Ω), where the subscripts characterize the variables (quantities) for differentiation and where
E,Ω
the symbols in the brackets describe the values of the variables. The values in the brackets are needed for special
function values (e.g. the energy distribution of the particle fluence at the energy E = E is written as Φ (E )). If no
0 E 0
special values are indicated, the brackets may be omitted.
3.1.2
particle fluence rate
fluence rate

Φ
dΦ d N

Φ ==
dt ddat×
where dΦ is the mean increment of the particle fluence (3.1.1) during an infinitesimal time interval with
duration dt
-2 −1 -2 −1
Note 1 to entry: The unit of the fluence rate is m ·s , a frequently used unit is cm ·s .
3.1.3
linear energy transfer
LET
L
Δ
quotient of the mean energy dE lost by the charged particles due to electronic interactions in traversing
Δ
a distance, dl, minus the mean sum of the kinetic energies in excess of Δ, of all the electrons released by
the charged particles and dl:
dE
Δ
L =
Δ
dl
where
L , i.e. with ∆ = ∞, is termed the unrestricted linear energy transfer in defining the quality factor
∞
L is also known as the restricted linear collision stopping power
∆
−1 −1
Note 1 to entry: The unit of the linear energy transfer is J·m , a frequently used unit is keV·μm .
3.1.4
dose equivalent
H
product of the absorbed dose D to tissue at the point of interest and the quality factor Q at that point:
HD= Q
Note 1 to entry: Q is determined by the unrestricted linear energy transfer, L (often denoted as L or LET), of
∞
charged particles passing through a small volume element (domains) at this point (the value of L is given for
∞
charged particles in water, not in tissue; the difference, however, is small). The dose equivalent at a point in tissue
is then given by:
∞
HQ= LD dL
()
L
∫
L=0
where D = dD/dL is the distribution of D in L at the point of interest.
L
Note 2 to entry: The relationship of Q and L is given in Reference [4].
−1
Note 3 to entry: The unit of dose equivalent is J·kg , called sievert (Sv).
ISO 20785-3:2023(E)
3.1.5
ambient dose equivalent
H*(10)
dose equivalent at a point in a radiation field, that would be produced by the corresponding expanded
and aligned field, in the ICRU sphere at 10 mm depth on the radius opposing the direction of the aligned
field
−1
Note 1 to entry: The unit of ambient dose equivalent is J·kg , called sievert (Sv).
3.1.6
correction factor
K
factor applied to the indication to correct for deviation of the measurement conditions from reference
conditions
3.1.7
standard barometric altitude
altitude determined by a barometric altimeter calibrated with reference to the International Standard
Atmosphere (ISA) when the altimeter's datum is set to 1 013,25 hPa
Note 1 to entry: The flight level is sometimes given as FL 350, where the number represents multiples of 100 feet
of standard barometric altitude, based on the ISA and a datum setting of 1 013,25 hPa. However, in some countries
flight levels are expressed in meters, in which case appropriate conversions should be made before applying the
data given in this document.
3.1.8
geomagnetic cut-off rigidity
cut-off rigidity
r
c
minimum magnetic r
...