EN ISO 11665-1:2015

SLOVENSKI STANDARD
01-november-2015
Merjenje radioaktivnosti v okolju - Zrak: radon-222 - 1. del: Radon in njegovi
kratkoživi razpadni produkti: izvori in merilne metode (ISO 11665-1:2012)
Measurement of radioactivity in the environment - Air: radon-222 - Part 1: Origins of
radon and its short-lived decay products and associated measurement methods (ISO
11665-1:2012)
Ermittlung der Radioaktivität in der Umwelt - Luft: Radon-222 - Teil 1: Radon und seine
kurzlebigen Folgeprodukte: Quellen und Messverfahren (ISO 11665-1:2012)
Mesurage de la radioactivité dans l'environnement - Air: radon 222 - Partie 1: Origine du
radon et de ses descendants à vie courte, et méthodes de mesure associées (ISO
11665-1:2012)
Ta slovenski standard je istoveten z: EN ISO 11665-1:2015
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11665-1
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2015
EUROPÄISCHE NORM
ICS 17.240
English Version
Measurement of radioactivity in the environment - Air:
radon-222 - Part 1: Origins of radon and its short-lived
decay products and associated measurement methods
(ISO 11665-1:2012)
Mesurage de la radioactivité dans l'environnement - Ermittlung der Radioaktivität in der Umwelt - Luft:
Air: radon 222 - Partie 1: Origine du radon et de ses Radon-222 - Teil 1: Radon und seine kurzlebigen
descendants à vie courte, et méthodes de mesure Folgeprodukte: Quellen und Messverfahren (ISO
associées (ISO 11665-1:2012) 11665-1:2012)
This European Standard was approved by CEN on 12 June 2015.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11665-1:2015 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
European foreword
The text of ISO 11665-1:2012 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 11665-1:2015 by 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 March 2016, and conflicting national standards shall
be withdrawn at the latest by March 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 11665-1:2012 has been approved by CEN as EN ISO 11665-1:2015 without any
modification.
INTERNATIONAL ISO
STANDARD 11665-1
First edition
2012-07-15
Measurement of radioactivity in the
environment — Air: radon-222 —
Part 1:
Origins of radon and its short-lived
decay products and associated
measurement methods
Mesurage de la radioactivité dans l’environnement — Air: radon 222 —
Partie 1: Origine du radon et de ses descendants à vie courte, et
méthodes de mesure associées
Reference number
ISO 11665-1:2012(E)
©
ISO 2012
ISO 11665-1:2012(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 8
4 Principle . 9
5 Equipment . 9
6 Sampling .10
6.1 General .10
6.2 Sampling objective .10
6.3 Sampling characteristics .10
6.4 Sampling conditions . 11
7 Detection .12
7.1 Silver-activated zinc sulphide ZnS(Ag) scintillation .12
7.2 Gamma-ray spectrometry .13
7.3 Liquid scintillation .13
7.4 Air ionization .13
7.5 Semi-conductor (alpha detection) .13
7.6 Solid-state nuclear track detectors (SSNTD) .13
7.7 Discharge of polarised surface inside an ionization chamber .13
8 Measurement .13
8.1 Methods .13
8.2 Influence quantities .14
8.3 Calibration .15
8.4 Quality control .15
9 Expression of results .15
10 Test report .15
Annex A (informative) Radon and its decay products — General information .17
Annex B (informative) Example of results of spot, integrated and continuous measurements of
radon-222 activity concentration .25
Annex C (informative) Example of a test report .27
Bibliography .28
ISO 11665-1:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 11665-1 was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
ISO 11665 consists of the following parts, under the general title Measurement of radioactivity in the
environment — Air: radon-222:
— Part 1: Origins of radon and its short-lived decay products and associated measurement methods
— Part 2: Integrated measurement method for determining average potential alpha energy concentration of
its short-lived decay products
— Part 3: Spot measurement method of the potential alpha energy concentration of its short-lived decay products
— Part 4: Integrated measurement method for determining average activity concentration using passive
sampling and delayed analysis
— Part 5: Continuous measurement method of the activity concentration
— Part 6: Spot measurement method of the activity concentration
— Part 7: Accumulation method for estimating surface exhalation rate
— Part 8: Methodologies for initial and additional investigations in buildings
The following parts are under preparation:
— Part 9: Method for determining exhalation rate of dense building materials
— Part 10: Determination of diffusion coefficient in waterproof materials using activity concentration measurement
iv © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
Introduction
Radon isotopes 222, 220 and 219 are radioactive gases produced by the disintegration of radium isotopes 226,
224 and 223, which are decay products of uranium-238, thorium-232 and uranium-235 respectively, and are
all found in the earth’s crust (see Annex A for further information). Solid elements, also radioactive, followed by
[1]
stable lead are produced by radon disintegration .
Radon is considered a noble gas in the periodic table of elements, along with helium, argon, neon, krypton and
xenon.
When disintegrating, radon emits alpha particles and generates solid decay products, which are also radioactive
(polonium, bismuth, lead, etc.). The potential effects on human health of radon lie in its decay products rather
than the gas itself. Whether or not they are attached to atmospheric aerosols, radon decay products can be
[2][3][4][5]
inhaled and deposited in the bronchopulmonary tree to varying depths according to their size .
Radon is today considered to be the main source of human exposure to natural radiation. The UNSCEAR
[6]
(2006) report suggests that, at the worldwide level, radon accounts for around 52 % of global average
exposure to natural radiation. The radiological impact of isotope 222 (48 %) is far more significant than isotope
220 (4 %), while isotope 219 is considered negligible (see Annex A). For this reason, references to radon in this
part of ISO 11665 refer only to radon-222.
Radon activity concentration can vary by one to multiple orders of magnitude over time and space. Exposure
to radon and its decay products varies tremendously from one area to another, as it depends firstly on the
amount of radon emitted by the soil and the building materials in each area and, secondly, on the degree of
containment and weather conditions in the areas where individuals are exposed.
The values usually found in the continental environment are normally between a few becquerels per cubic
metre and several thousand becquerels per cubic metre. Activity concentrations of less than one becquerel per
cubic metre may be observed in the oceanic environment. Radon activity concentrations vary inside houses
[7]
from several tens of becquerels per cubic metre to several hundreds of becquerels per cubic metre . Activity
concentration can reach several thousands of becquerels per cubic metre in very confined spaces. Variations
of a few nanojoules per cubic metre to several thousand nanojoules per cubic metre are observed for the
potential alpha energy concentration of short-lived radon decay products.
ISO 11665 consists of 10 parts (see Figure 1) dealing with:
— measurement methods for radon-222 and its short-lived decay products (see ISO 11665-2, ISO 11665-3,
ISO 11665-4, ISO 11665-5 and ISO 11665-6);
NOTE 1 There are many methods for measuring the radon-222 activity concentration and the potential alpha energy
concentration of its short-lived decay products. The choice of measurement method will depend on the expected level of
[8][9]
concentration and on the intended use of the data, such as scientific research and health-related assessments .
— measurement methods for the radon-222 exhalation rate (see ISO 11665-7 and ISO 11665-9);
NOTE 2 ISO 11665-7 refers back to ISO 11665-5 and ISO 11665-6.
— measurement methods for the radon-222 diffusion coefficient (see ISO 11665-10);
— methodologies for radon-222 measurements in buildings (see ISO 11665-8).
NOTE 3 ISO 11665-8 refers back to ISO 11665-4 for radon measurements for initial investigation purposes in a building
and to ISO 11665-5, ISO 11665-6 and ISO 11665-7 for measurements for any additional investigation.
ISO 11665-1:2012(E)
ISO 11665-1
Origins of radon and its
short-lived decay products
and associated
measurement methods
MEASUREMENT APPLICATION
ISO 11665-2 ISO 11665-4
ISO 11665-7
Integrated measurement Integrated measurement
Accumulation method
method for determining method for determining
for estimating surface
average potential alpha energy average activity concentration
exhalation rate
concentration of its short-lived using passive sampling and
delayed analysis
decay products
ISO 11665-3
ISO 11665-5 11665-8
Spot measurement method
Continuous measurement Methodologies for initial
of the potential alpha energy
method of the activity and additional investigations
concentration of its short-lived
concentration in buildings
decay products
ISO 11665-6 11665-9
Spot measurement Method for determining
method of the activity exhalation rate of
concentration dense building materials
ISO 11665-10
Determination of diffusion
coefficient in waterproof
materials using activity
concentration measurement
Figure 1 — Structure of the ISO 11665 series
vi © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 11665-1:2012(E)
Measurement of radioactivity in the environment — Air:
radon-222 —
Part 1:
Origins of radon and its short-lived decay products and
associated measurement methods
1 Scope
This part of ISO 11665 outlines guidance for measuring radon-222 activity concentration and the potential
alpha energy concentration of its short-lived decay products in the air.
The measurement methods fall into three categories:
a) spot measurement methods;
b) continuous measurement methods;
c) integrated measurement methods.
This part of ISO 11665 provides several methods commonly used for measuring radon-222 and its short-lived
decay products in air.
This part of ISO 11665 also provides guidance on the determination of the inherent uncertainty linked to the
measurement methods described in its different parts.
2 Normative references
The following referenced documents are indispensable for the application 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 17025, General requirements for the competence of testing and calibration laboratories
IEC 61577-1, Radiation protection instrumentation — Radon and radon decay product measuring instruments —
Part 1: General principles
IEC 61577-2, Radiation protection instrumentation — Radon and radon decay product measuring instruments —
Part 2: Specific requirements for radon measuring instruments
IEC 61577-3, Radiation protection instrumentation — Radon and radon decay product measuring instruments —
Part 3: Specific requirements for radon decay product measuring instruments
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
active sampling
sampling using active devices like pumps for sampling the atmosphere
[IEC 61577-1:2006]
ISO 11665-1:2012(E)
3.1.2
activity
disintegration rate
number of spontaneous nuclear disintegrations occurring in a given quantity of material during a suitably small
interval of time divided by that interval of time
[ISO 921:1997, term 23]
NOTE 1 Activity, A, is expressed by the relationship given in Formula (1):
AN=⋅λ (1)
where
λ is the decay constant per second;
N is the number of atoms.
NOTE 2 The decay constant is linked to the radioactive half-life by the relationship:
ln 2
λ = (2)
T
12/
where
T is the radioactive half-life, in seconds.
1/2
3.1.3
activity concentration
activity per unit volume
[IEC 61577-1:2006]
3.1.4
attached fraction
fraction of the potential alpha energy concentration of short-lived decay products that is attached to the
ambient aerosol
[IEC 61577-1:2006]
NOTE The sizes of the carrier aerosol to which most of the short-lived decay products are attached are generally in
the 0,1 μm to 0,3 μm range of median values.
3.1.5
average activity concentration
exposure to activity concentration divided by the sampling duration
3.1.6
average potential alpha energy concentration
exposure to potential alpha energy concentration divided by the sampling duration
3.1.7
background noise
signals caused by something other than the radiation to be detected
NOTE A distinction can be made between signals caused by radiation from sources inside or outside the detector
other than those targeted for the measurements and signals caused by defects in the detection system electronic circuits
and their electrical power supply.
2 © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
3.1.8
continuous measurement
measurement obtained by taking a sample continuously (or at integration intervals typically in range of 1 min to
120 min) with simultaneous or slightly delayed analysis
NOTE 1 The sampling duration shall be adapted to the dynamics of the phenomenon studied to monitor the evolution
of radon activity concentration over time.
NOTE 2 See Annex B for further information.
3.1.9
diffusion length
distance crossed by an atom due to diffusion forces before decaying
NOTE Diffusion length, l, is expressed by the relationship given in Formula (3):
 D 
l = (3)
 
λ
 
where
D is the diffusion coefficient, in square metres per second;
λ is the decay constant per second.
3.1.10
equilibrium factor
ratio of the potential alpha energy concentration of short-lived radon decay products in a given volume of air
to the potential alpha energy concentration of these decay products if these are in radioactive equilibrium with
radon in the same volume of air
NOTE 1 The short-lived Rn decay products present in an atmosphere are very rarely in radioactive equilibrium with
their parent (through being trapped on the walls or eliminated by an air renewal system, for example) and the equilibrium
factor is used to qualify this state of “non-equilibrium”.
NOTE 2 The equilibrium factor is between 0 and 1. The equilibrium factor in buildings typically varies between 0,1 and
[4][6]
0,9, with an average value equal to 0,4 .
NOTE 3 The equilibrium factor, F , is expressed by Formula (4):
eq
E
PAEC,222
Rn
F = (4)
eq
−9
55, 71⋅×0 C
Rn
where
is the potential alpha energy concentration of Rn, in joules per cubic metre;
E
PAEC,222
Rn
−9
is the potential alpha energy concentration of the short-lived Rn decay products for 1 Bq of
55, 71× 0
Rn in equilibrium with its short-lived decay products, in joules per becquerel;
is the activity concentration of Rn, in becquerels per cubic metre.
C
Rn
3.1.11
grab sampling
collection of a sample (i.e of air containing radon or aerosol particles) during a period considered short
compared with the fluctuations of the quantity under study (i.e volume activity of air)
[IEC 61577-1:2006]
ISO 11665-1:2012(E)
3.1.12
guideline value
value which corresponds to scientific, legal or other requirements and which is intended to be assessed by the
measurement procedure
NOTE 1 The guideline value can be given, for example, as an activity, a specific activity or an activity concentration, a
surface activity, or a dose rate.
NOTE 2 The comparison of the detection limit with a guideline value allows a decision on whether or not the measurement
procedure satisfies the requirements set forth by the guideline value and is therefore suitable for the intended measurement
purpose. The measurement procedure satisfies the requirement if the detection limit is smaller than the guideline value.
[ISO 11929:2010, term 3.10]
3.1.13
integrated measurement
measurement performed by continuous sampling of a volume of air which, over time, is accumulating physical
quantities (number of nuclear tracks, number of electric charges, etc.) linked to the disintegration of radon
and/or its decay products, followed by analysis at the end of the accumulation period
NOTE See Annex B for further information.
3.1.14
long-term measurement
measurement based on an air sample collected within a period greater than one month
3.1.15
measurand
quantity intended to be measured
[ISO/IEC Guide 99:2007, term 2.3]
3.1.16
measuring system
set of one or more measuring instruments and often other devices, including any reagent and supply, assembled
and adapted to give information used to generate measured quantity values within specified intervals for
quantities of specified kinds
[ISO/IEC Guide 99:2007, term 3.2]
3.1.17
passive sampling
sampling using no active devices such as pumps for sampling the atmosphere, whereby in most instruments
sampling is performed mainly by diffusion
NOTE Adapted from IEC 61577-1:2006.
3.1.18
potential alpha energy of short-lived radon decay products
total alpha energy emitted during the decay of atoms of short-lived radon decay products along the decay chain
210 222
through to Pb for the decay chains of the Rn
NOTE 1 The potential alpha energy of short-lived Rn decay products, E , is expressed by Formula (5):
PAE,222
Rn
 
EE+ ⋅ N
()AE,218 AE,214 ()218
Po Po Po
 
E = (5)
PAE,222
Rn  
+⋅EN ++NE+⋅ N
 AE,214 ()214 214 AE,214 ()214 
Po Pb Bi Po Po
 
4 © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
where
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,218
Po
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,214
Po
is the number of atoms of Po;
N
Po
is the number of atoms of Pb;
N
Pb
is the number of atoms of Bi;
N
Bi
is the number of atoms of Po.
N
Po
NOTE 2 The total alpha energy emitted during the decay of atoms of short-lived radon decay products along the decay
208 220
chain through to Pb for the decay chains of the Rn is expressed by Formula (6):
 
EE+⋅03,,60+⋅64 EN⋅
()AE,216 AE,212 AE,212 ()216
Po Bi Po Poo
 
E = (6)
PAE,220
 
Rn
+⋅03,,60EE+⋅64 ⋅+NN +E ⋅ N
() () ()
 AE,212 AE,212 212 212 AE,2112 212 
Bi Po Pb Bi Po Po
 
where
is the potential alpha energy of Rn, in joules;
E
PAE,220
Rn
E is the alpha particle energy produced by the disintegration of Po, in joules;
AE,216
Po
is the alpha particle energy produced by the disintegration of Bi, in joules;
E
AE,212
Bi
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,212
Po
is the number of atoms of Pb;
N
Pb
N is the number of atoms of Bi;
Bi
is the number of atoms of Po.
N
Po
3.1.19
potential alpha energy concentration of short-lived radon decay products
concentration of any mixture of short-lived radon decay products in air in terms of the alpha energy released
210 208
during complete decay through Pb and/or Pb respectively
[IEC 61577-1:2006]
NOTE The potential alpha energy concentration of the nuclide i, E , is expressed by Formula (7):
PAEC,i
E
PAE,i
E = (7)
PAEC,i
V
where
E is the potential alpha energy of the nuclide i, in joules;
PAE,i
V is the sampled volume, in cubic metres.
ISO 11665-1:2012(E)
3.1.20
potential alpha energy concentration exposure
integral with respect to time of potential alpha energy concentration accumulated during the exposure time
NOTE Exposure to potential alpha energy concentration, X , is expressed by Formula (8):
PAEC
t
XE=⋅dt (8)
PAEC PAEC
∫
where
E is the potential alpha energy concentration, in joules per cubic metre;
PAEC
t is the sampling duration, in seconds.
3.1.21
primary standard
standard designed with, or widely acknowledged as having, the highest metrological qualities and whose value
is accepted without reference to other standards of the same quantity
[IEC 61577-1:2006]
NOTE The concept of a primary standard is equally valid for base quantities and derived quantities.
3.1.22
radioactive equilibrium of radon-222 with its short-lived decay products
state of radon and its short-lived decay products whereby the activity of each radionuclide is equal
NOTE In radioactive equilibrium, the activity of each short-lived decay product decreases over time like the radon activity.
3.1.23
radon emanation
mechanism whereby a radon atom leaves the individual particle of solid material in which it has been formed
and reaches the free space of pores
3.1.24
radon exhalation
mechanism whereby a radon atom produced by emanation and transported (by diffusion or convection) towards
the material surface is released from the material into the surrounding medium (air)
3.1.25
radon exhalation rate
value of the activity concentration of radon atoms that leave a material per unit time
NOTE 1 The radon exhalation rate under conditions whereby the radon activity concentration at the surface of the
material equals zero is called free radon exhalation rate.
NOTE 2 The free radon exhalation rate is approximated from the radon exhalation rate if the radon activity at the
surface of the material has a sufficiently low value.
3.1.26
radon surface exhalation rate
value of the activity concentration of radon atoms that leave a material per unit surface of the material per unit time
3.1.27
radon mass exhalation rate
value of the activity concentration of radon atoms that leave a material per unit mass of the material per unit time
6 © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
3.1.28
radon exposure
integral with respect to time of radon activity concentration accumulated during the exposure time
NOTE Exposure to radon, X, is expressed by Formula (9):
t
XC= dt (9)
∫
where
C is the activity concentration, in becquerels per cubic metre.
t is the sampling duration, in seconds.
3.1.29
reference atmosphere
radioactive atmosphere in which the influence quantities (aerosols, radioactivity, climatic conditions, etc.) are
sufficiently well-known or controlled to allow its use in a testing procedure for measuring instruments for radon
or short-lived decay products
NOTE 1 The parameter values concerned shall be traceable to recognized standards.
NOTE 2 Adapted from IEC 61577-1:2006.
3.1.30
reference source
radioactive secondary standard source for use in the calibration of the measuring instruments
[IEC 61577-1:2006]
3.1.31
sampling duration
time interval during which the sampling is performed at a given point
3.1.32
sampling plan
precise protocol that, depending on the application of the principles of the strategy adopted, defines the spatial
and temporal dimensions of sampling, the frequency, the sample number, the quantities sampled, etc., and the
human resources to be used for the sampling operation
NOTE See ISO/IEC 17025:2005, 5.7, for further information on sampling plans.
3.1.33
sampling strategy
set of technical principles that aim to resolve, depending on the objectives and site considered, the two main
issues which are the sampling density and the spatial distribution of the sampling areas
NOTE The sampling strategy provides the set of technical options that will be required in the sampling plan.
3.1.34
sensor
element of a measuring system that is directly affected by a phenomenon body, or substance carrying a
quantity to be measured
[ISO/IEC Guide 99:2007, term 3.8]
NOTE The term “detector” is also used for this concept.
ISO 11665-1:2012(E)
3.1.35
short-lived decay products
radionuclides with a half-life of less than one hour produced by radon-222 disintegration ( Rn): polonium-218
218 214 214 214
( Po), lead-214 ( Pb), bismuth-214 ( Bi) and polonium-214 ( Po)
See Figure A.1.
216 212
NOTE Decay products of radon-220 disintegration such as polonium-216 ( Po), lead-212 ( Pb), bismuth-212
212 212 208
( Bi), polonium-212 ( Po) and thallium-208 ( Tl) can interfere with the radon-222 measurement (see Figure A.2).
3.1.36
short-term measurement
measurement based on an air sample collected within a period comparable to the duration of the half-life of radon
3.1.37
spot measurement
measurement based on a grab sample taken within a period of less than one hour, at a given point in space,
together with an analysis (e.g. count) carried out simultaneously or after a set period of time
NOTE See Annex B for further information.
3.1.38
unattached fraction of E
PAEC,222
Rn
fraction of the potential alpha energy concentration of short-lived decay products that is not attached to the
ambient aerosol
[IEC 61577-1:2006]
NOTE 1 The particle size concerned is in the order of magnitude of nanometres.
220 212 220
NOTE 2 In the case of Rn, the relatively long half-life of Pb can lead to cases where Rn completely disappears
before Bi; in this case, the unattached fraction of short-lived radon-220 decay products cannot be defined.
3.2 Symbols
For the purposes of this document the following symbols apply.
activity of the nuclide i, in becquerels
A
i
activity concentration of the nuclide i, in becquerels per cubic metre
C
i
average activity concentration of the nuclide i, in becquerels per cubic metre
C
i
D
diffusion coefficient, in square metres per second
E alpha particle energy produced by the disintegration of the nuclide i, in joules
AE,i
potential alpha energy of the nuclide i, in joules
E
PAE,i
E potential alpha energy concentration of the nuclide i, in joules per cubic metre
PAEC,i
average potential alpha energy of the nuclide i, in joules
E
PAE,i
average potential alpha energy concentration of the nuclide i, in joules per cubic metre
E
PAEC,i
equilibrium factor (dimensionless)
F
eq
8 © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
l diffusion length, in metres
N number of atoms of the nuclide i
i
radioactive half-life of the nuclide i, in seconds
T
12/,i
t
sampling duration, in seconds
U
Uk=⋅u() k = 2
expanded uncertainty calculated by with
standard uncertainty associated with the measurement result
u
()
V sampled volume, in cubic metres
X
exposure to radon, in becquerel-hours per cubic metre
X potential alpha energy concentration exposure, in joule-hours per cubic metre
PAEC
Y primary measurement result of the measurand
∗
decision threshold of the measurand
y
#
detection limit of the measurand
y

lower limit of the confidence interval of the measurand
y

upper limit of the confidence interval of the measurand
y
φ exhalation rate, in becquerels per square metre per second
φ free exhalation rate, in becquerels per square metre per second
f
φ mass exhalation rate, in becquerels per square metre per second
m
surface exhalation rate, in becquerels per square metre per second
φ
s
decay constant of the nuclide i, per second
λ
i
4 Principle
The measurement methods presented in this part of ISO 11665 are based on the following elements:
a) sampling a volume of air representative of the atmosphere under investigation;
b) detecting radiations produced by successive radioactive disintegrations of the radon isotopes and their
decay products.
NOTE Examples of results for radon activity concentration measurements are given in Annex B.
5 Equipment
Equipment is specific to the different measurement methods and is described in the various parts of ISO 11665.
Equipment shall be in accordance with IEC 61577-1, IEC 61577-2 and IEC 61577-3.
ISO 11665-1:2012(E)
6 Sampling
6.1 General
Selection of the appropriate sampling method will depend on the site under investigation (mines, outdoors,
houses, buildings open to the public, workplaces, etc.), the intended use of the data and the anticipated level
of radon activity concentration.
The radon activity concentration and the potential alpha energy concentration of its decay products vary
tremendously over time (see Annex A). More than one order of magnitude in variation can be observed over
time at the same place and thus measurement results will depend on the sampling duration, which can extend
[10]
from a few minutes to a few hours or several months and on the sampling date (see Figure B.2).
The extrapolation from an average activity concentration obtained from a measurement performed during
a given sampling duration at a given sampling time to an average activity concentration representative of
a different sampling duration and/or sampling time requires knowledge of the radon activity concentration
variability over the inferred period. In some cases, the uncertainty attached to this variability can be so large
that such an extrapolation becomes meaningless for the objective of the measurement.
It is therefore important that the choice of sampling method and duration and time of sampling is compatible
with the measurement objective and its required uncertainty. For these reasons, the measurement results
following screening of an area over a short sampling period need to be interpreted with caution.
The sampling process will be performed using different approaches or sampling strategies depending on the
objective pursued. Whatever this objective might be, the sampling strategy should be carefully selected, as it
determines a large number of decisions and can generate important and costly activities.
Radon activity concentration measurement results and the potential alpha energy concentration measurement
results can only be correctly interpreted if the sample is representative of the air that is being characterized.
The definition of the sampling strategy shall follow, as far as possible, the following stages:
a) analysis of records to enable an historic study of the previous use of the sampling site;
b) site reconnaissance (in some cases, analytic investigation techniques using portable radioactivity
detectors, may be used to identify the areas to be studied in detail);
c) identification of preferential migration pathways and/or accumulation areas;
d) site reconnaissance with respect to the sampling to be undertaken.
The implementation of this strategy, which also includes the definition of the data quality objectives according
to the parameters to be analysed, gives rise to the sampling plan.
The sampling plan shall define the operations to be carried out as defined in ISO/IEC 17025.
6.2 Sampling objective
The objective of the sampling is to provide sufficient representative samples in order that the measurement
results comply with their intended use.
6.3 Sampling characteristics
The sampling can be either active or passive.
The sampling time (date and hour), duration and location, and whether sampling is active or passive, shall be
specified for all measurements of radon and decay products in the environment or in a confined atmosphere.
The sampling characteristics relating to each measurement method of radon and its decay products are
described in the various parts of ISO 11665.
10 © ISO 2012 – All rights reserved

ISO 11665-1:2012(E)
6.4 Sampling conditions
6.4.1 Installation of sampling device
6.4.1.1 Sampling outside a building
Sampling locations shall be distributed outside the building taking into account the following parameters:
topography, prevailing winds, activity zones (urban, manufacturing, agricultural and domestic) and potential
release points.
In an open area, sampling shall be representative of the air to be measured. Any natural and artificial obstacles
(apart from weather shelters) shall be outside an inverted cone with a 140° opening at the top and the sampling
[11]
point at the bottom tip, and outside a sphere with a 1 m diameter centred on the sampling location (see
Figure 2). The sampling location shall be between 1 m and 2 m above the supporting surface (e.g. ground).
The installation shall not disturb the surrounding atmosphere.
Key
1 ground
2 bracket
3 sphere free of obstacles (1 m in diameter)
4 sampling place
5 weather shelter
6 cone free of obstacles (140°)
Figure 2 — Example of diagram of a sampling place outside a building
6.4.1.2 Sampling inside a building
The selected number of samples and their location inside a building is determined by the intended use of
the measurement results (initial investigations, search for radioactive sources, radionuclide transfer study,
verification of homogeneity of a parameter measured in an environment or identification of anomalies,
ISO 11665-1:2012(E)
assessment of human exposure, etc.) taking into account the architectural characteristics of the building (crawl
space, basement, multiple storeys, earthen floor, building materials, etc.), the room characteristics and also the
measuring equipment used (see ISO 11665-8).
6.4.2 Sampling duration
The sampling duration can vary from a few minutes to a few hours or several months.
Due to the great variability of both radon activity concentration and potential alpha energy concentration in
time and space (see Annex A), the sampling duration shall be determined according to the intended use of the
measurement results (see Table 1).
Table 1 — Sampling duration based on type of sampling
Characteristics Usual sampling
Measurement Characteristics of the measurement result
of sampling duration
Less than one Representative only of the activity concentration at a given
Spot Grab
hour moment and a given point
Representa
...