ISO/TR 24107:2024
(Main)Air quality — Validation of air quality measurement methods in the standardization process
Air quality — Validation of air quality measurement methods in the standardization process
This document provides an overview of the validation of air quality measurement methods in the standardization process. This document deals with robustness testing and interlaboratory testing as the two main steps of partial and full validation. It applies to the different inter-related elements of air quality measurement methods, covering e.g. sampling, sample preparation, storage and transportation of the sample, extraction, analysis or quantification of a measured component and reporting. Consequently, this document focuses on the "why" and "what" of validation tasks in direct relation to the different steps of the standardization process. This document is focused on the validation tasks for measurement methods either for the whole measurement process or for one of its constituent parts. Given the informative aim of this document, it does not contain detailed procedures for performing the validation tasks, such as number of laboratories, number of samples, etc. This document is relevant to measurement methods in ISO/TC 146 and all of its subcommittees.
Qualité de l'air — La validation des méthodes de mesure de la qualité de l'air dans le processus de normalisation
General Information
Standards Content (Sample)
Technical
Report
ISO/TR 24107
First edition
Air quality — Validation of air
2024-12
quality measurement methods in
the standardization process
Qualité de l'air — La validation des méthodes de mesure de la
qualité de l'air dans le processus de normalisation
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Purposes for validation . 4
6 Objectives for validation . 5
7 Types of validation . 5
7.1 Validation of reference methods .5
7.2 Validation of alternative methods .7
7.3 Validation in the absence of certified reference materials .7
8 Objective, design and documentation of a validation study . 8
8.1 General .8
8.2 Objective of a validation study .8
8.2.1 General .8
8.2.2 Purpose(s) for performing the measurement .8
8.2.3 Representative sampling .8
8.2.4 Sample preparation .8
8.2.5 Analysis .9
8.2.6 Performance characteristics .9
8.2.7 Determination of the result of measurement and the associated measurement
uncertainty .9
8.2.8 Documentation and reporting .9
8.3 Design of the validation study .9
8.4 Documentation of the validation study .10
8.4.1 Report on the validation study .10
8.4.2 Storage of results of the validation study .10
9 Examples of validation procedures for specific types of measurement method .11
9.1 General .11
9.2 Stationary source emissions .11
9.2.1 General .11
9.2.2 Manual measurement methods .11
9.2.3 Automated measurement methods .11
9.2.4 Test bench validation . .11
9.2.5 Field test validation . 12
9.2.6 Final evaluation . 12
9.3 Workplace atmospheres . . 12
9.4 Ambient atmospheres . 12
9.5 Meteorology . 12
9.6 Indoor air . 12
Annex A (informative) Stationary source emissions . 14
Annex B (informative) Workplace atmospheres .35
Annex C (informative) Ambient atmospheres . 47
Annex D (informative) Meteorology .50
Annex E (informative) Indoor air . 51
Annex F (informative) Information from other sources .54
Bibliography .56
iii
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,
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 4, General
aspects.
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
Introduction
ISO/IEC 17025 defines expectations for verification and validation of test methods. These expectations are
based on definitions in ISO/IEC Guide 99 and aim to ensure that test methods are suitable for their intended
use and that test results have a known, documented level of quality.
This document describes protocols that have been used within ISO/TC 146 and other technical committees
on air quality to verify and validate measurement methods. It also establishes guidance intended to be used
for method validation. This document seeks to establish a consistent framework for method validation
within ISO/TC 146 and its subcommittees.
v
Technical Report ISO/TR 24107:2024(en)
Air quality — Validation of air quality measurement methods
in the standardization process
1 Scope
This document provides an overview of the validation of air quality measurement methods in the
standardization process.
This document deals with robustness testing and interlaboratory testing as the two main steps of partial
and full validation. It applies to the different inter-related elements of air quality measurement methods,
covering e.g. sampling, sample preparation, storage and transportation of the sample, extraction, analysis or
quantification of a measured component and reporting.
Consequently, this document focuses on the "why" and "what" of validation tasks in direct relation to
the different steps of the standardization process. This document is focused on the validation tasks for
measurement methods either for the whole measurement process or for one of its constituent parts.
Given the informative aim of this document, it does not contain detailed procedures for performing the
validation tasks, such as number of laboratories, number of samples, etc.
This document is relevant to measurement methods in ISO/TC 146 and all of its subcommittees.
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 4225, Air quality — General aspects — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4225 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
verification
provision of objective evidence that a given item fulfils specified requirements
[SOURCE: ISO/IEC Guide 99:2007, 2.44]
3.2
validation
verification, where the specified requirements are adequate for an intended use
[SOURCE: ISO/IEC Guide 99:2007, 2.45]
3.3
method
measurement procedure
detailed description of a measurement according to one or more measurement principles and to a
given measurement method, based on a measurement model and including any calculation to obtain a
measurement result
[SOURCE: ISO/IEC Guide 99:2007, 2.6, modified — Notes to entry omitted]
3.4
measurement method
method of measurement
generic description of a logical organization of operations used in a measurement
[SOURCE: ISO/IEC Guide 99:2007, 2.5, modified — Note to entry omitted]
3.5
reference method
RM
measurement method taken as a reference, which gives the reference value of the measurand
Note 1 to entry: A reference method is fully described.
Note 2 to entry: A reference method can be a manual or an automated method.
3.6
alternative method
AM
measurement method which complies with the criteria given by the reference method
Note 1 to entry: An alternative method can consist of a simplification of the reference method.
Note 2 to entry: Alternative methods can be used if equivalence to the reference method has been demonstrated.
3.7
evaluation
examination of validation data to determine suitability for intended use(s)
3.8
sensitivity
change in instrument response which corresponds to a change in the measured
quantity
3.9
selectivity
extent to which the method can be used to determine particular analytes in mixtures
or matrices without interferences from other components of similar behaviour
3.10
linearity
ability to use a straight line to describe the relationship between a measurement
result and concentration of the analyte of interest
3.11
robustness
measure of the capacity of an analytical method to remain unaffected within
specified limits by small, but deliberate variations in method parameters
3.12
repeatability
measurement repeatability
measurement precision under a set of repeatability conditions of measurement
[SOURCE: ISO/IEC Guide 99:2007, 2.21]
3.13
repeatability condition
repeatability condition of measurement
condition of measurement, out of a set of conditions that includes the same measurement procedure,
same operators, same measuring system, same operating conditions and same location, and replicate
measurements on the same or similar objects over a short period of time
[SOURCE: ISO/IEC Guide 99:2007, 2.20, modified — Notes to entry omitted]
3.14
reproducibility
measurement reproducibility
measurement precision under reproducibility conditions of measurement
[SOURCE: ISO/IEC Guide 99:2007, 2.25, modified — Note to entry omitted]
3.15
reproducibility condition
reproducibility condition of measurement
condition of measurement, out of a set of conditions that includes different locations, operators, measuring
systems, and replicate measurements on the same or similar objects
Note 1 to entry: The different measuring systems can use different measurement procedures.
[SOURCE: ISO/IEC Guide 99:2007, 2.24, modified — In Note 1 to entry, “may” changed to “can”; also, Note 2
to entry omitted]
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
AAS atomic absorption spectrometry
AM alternative method
CRF controlled release facility
FAIR findable, accessible, interoperable and reusable
FID flame ionisation detector
FTIR Fourier-transform infrared
ICP inductively coupled plasma
ICP-AES inductively coupled plasma atomic emission spectrometry
ICP-MS inductively coupled plasma mass spectrometry
LDAR leak detection and repair
LIDAR light detection and ranging
LOD limit of detection
LOQ limit of quantification
LV limit value
MSD mass selective detector
NPL National Physical Laboratory
OELV occupational exposure limit values
OGI optical gas imaging
P-AMS portable automated measuring systems
QA/QC quality assurance and quality control
RDM reverse dispersion modelling
RH relative humidity
RM reference method
SOF solar occultation flux
ST-OELV short-term occupational exposure limit values
STEL short-term exposure limits
TDL tuneable diode laser
TEM transmission electron microscopy
TDLAS tuneable diode laser absorption spectroscopy
TWA time-weighted average concentration
UV ultra-violet
VOC volatile organic compounds
WP work package
5 Purposes for validation
Validation is the process of defining an analytical requirement and confirming that the method under
consideration has capabilities consistent with what the application requires in view of the measurement
objective(s). This is often referred to as the method being fit for its intended purpose. An important part
of this process is determining the uncertainty of the measurement results and whether this is suitable for
the intended use, e.g. a maximum specific limit. It is also important to determine if it provides sufficient
confidence in conclusions to be drawn from the measurement results.
Often, validation campaigns are designed to determine both an uncertainty associated with the entire
measurement method and individual uncertainty components (i.e. various bias and precision terms)
associated with individual components of the method. Either selectivity, limit of detection or limit of
quantification, or a combination, can also be relevant. This supports the elaboration of the measurement
method in terms of providing confidence that any maximum permissible uncertainty that is required for
the entire method is fit for the intended application. It also supports the specification of any uncertainty
requirement for individual components of the measurement method. Furthermore, validation campaigns
confirm that reliable measurement results can be achieved by competent end users. Subsequently, this also
serves to ensure that fit for purpose and achievable requirements are set by proficiency testing providers
(and equally importantly local competent authorities and national accreditation bodies) in assessing the
competence of end users.
In the absence of full or partial validation, requirements in the measurement method are based on expert
opinion. With no evidential data there is therefore a higher level of uncertainty at a given level of confidence
that the measurement method has capabilities consistent with what the application requires, and that
requirements placed upon end users by the measurement method are realistic and achievable.
6 Objectives for validation
The main objectives of validation are confirming that:
— the measurement method meets the requirements specified in the measurement objective;
— the measurement method specified in the standard is clearly described and practicable, or if collecting
of improvement proposals is needed;
— the results are comparable when different testing laboratories or institutes use the measurement method
for the same task.
NOTE Comparability can be quantified by e.g. repeatability and reproducibility.
Method validation is a process to verify that a measurement method fulfils specified requirements that are
[2]
adequate for an intended use. It is a series of actions, following development of a method but preceding
routine implementation of the method, that demonstrates and documents the fitness of the method for the
intended use.
The principal benefit of validation is to provide confidence that measurements made by using the
measurement method provide data which can be relied upon by the end user(s) for making correct decisions
in one or more of the following areas:
— process control;
— policy making;
— compliance with regulatory requirements (e.g. limit values for emissions or occupational exposure);
— suitability of modelling (e.g. atmospheric modelling).
Measurement methods contained in documents prepared by technical committees on air quality are
intended for use in a variety of locations and with a variety of sampling and laboratory equipment. It is
expected that a standard method, when properly used, provides consistent measurement results wherever
it is used. Additionally, since ISO/IEC 17025 recommends the use of standard methods when available, it is
incumbent for those who establish such methods (e.g. ISO/TC 146) to ensure a sufficient degree of validation
to support their use in this manner.
Additional considerations are given in 8.2.
7 Types of validation
7.1 Validation of reference methods
Reference methods (RM) are measurement methods that have been validated and of which the quality of
the measurement method is, given a specific field of application, fit for its intended purpose and accepted by
experts and users. Knowledge on and documentation of the quality of the measurement method is essential
to define it as a RM. Validation is therefore an essential step in the standardization process.
RM can be used as a legal reference in either legislation, regulation or in contracts between two or more
parties, or a combination thereof. They need, therefore, to be self-supportive. RM are not necessarily of the
highest metrological quality. However, experts define a reference method as "reliable" and a good basis for
decisions. In general, RM are "fit for purpose" in view of the measurement objective.
Validation of measurement methods is generally performed in two steps including performance
characteristics relevant for the considered measurement method:
— robustness testing;
— interlaboratory testing.
As the first step is based on a first draft of the standard and each of the validation steps result in a revised
draft standard, the implementation of validation in the standardization process normally relates to three
different draft standards, the last one of which is published as a standard.
Cases can occur where the current state of the art is not sufficient for the efficient further development
of the envisaged standard. In such a case, a so-called pre-normative research can be needed prior to any
standardization with validation.
The robustness testing is generally performed by one or more competent laboratories which ideally already
have experience with the new measurement method. The performance characteristics of the measurement
method are determined through inter-laboratory experiments. Both steps are needed and contribute to the
evaluation of the uncertainty of the measurement results.
The comparability of measurement results obtained by the standardized measurement method is ensured
by metrological traceability of the measurement results by means of a documented unbroken chain of
calibrations, each contributing to the measurement uncertainty, linking them to an appropriate reference.
Metrological traceability to the International System of Units (SI) can be achieved through:
— calibration provided by a competent laboratory; or
— certified reference materials with a stated metrological traceability to the SI units; or
— direct realization of the SI units.
When metrological traceability to the SI units is not technically possible, the metrological traceability can
be ensured by use of an appropriate reference, e.g.
— reference materials without a stated metrological traceability to the SI units;
— results of RM, specified methods or consensus standards that are clearly described and accepted as
providing measurement results fit for their intended use and ensured by suitable comparison.
Unfortunately, there is a clear disadvantage with certified reference materials as these are only available
for a limited number of components and matrices and are, in general, so expensive that it is not financially
possible to use certified reference materials for validation or routine checks. Therefore, it is important to
specify in the standardized measurement method the appropriate reference.
The uncertainty of the measurement results obtained by the standardized measurement method consists of
the uncertainty contributions resulting from the unbroken chain of calibrations. Therefore, it is important
to specify in the standardized measurement method the minimum requirements for these uncertainty
contributions.
In specific cases the introduction of a new RM results in the withdrawal of a previous RM. For example,
due to the general application of new analytical instruments, the old RM is in practice no longer applicable.
Validation of the new RM and cross-comparison of the results of both the old and the new RM allows the
continuous use of data collected in the past (the "historical" data).
When a Technical Committee (TC) or Subcommittee (SC) starts a work item, this is generally given to a
dedicated working group (WG). The aim of the work is to harmonize as far as possible the practices on a
specific topic. Through a series of steps, consensus among the experts is achieved resulting in a first draft
standard that, to the opinion of the experts, reflects the state of the art (in terms of standardization) and is
assumed to be fit for purpose.
This first draft standard is used as a starting point for the validation work, or, if funds or means for validation
are not sufficiently available, can be adopted by the TC or SC members and published as a Technical
Specification (TS). When published as a TS, the document states that the measurement method has not been
validated.
In general, at least the following different levels of validation can be distinguished:
— full validation by sufficient funding, which means that robustness testing and inter-laboratory testing
(e.g. repeatability and reproducibility) as well as evaluation of the uncertainty are acceptably performed;
— partial validation in cases where results of a full validation are not available due to lack of funding, but a
set of validation data provided e.g. by at least one member country or one testing laboratory, on the basis
of current investigations being available and that expert assessment justifies the validity of these data;
— validation on the basis of existing historical data provided e.g. by at least one member country where the
measurement method has been validated on a national level and expert assessment justifies the validity
of these data.
7.2 Validation of alternative methods
In specific cases it can be necessary to standardize an alternative method (AM) to the already existing RM, e.g.
if a simplification of the RM is desirable or a different measurement technique is available. The scope of the
AM can be limited in comparison with the scope of the reference method, but is covered by the scope of RM.
With respect to validation, an AM is treated as outlined in 7.1 for the RM, but often with a limited scope in
comparison with the RM. In addition, the equivalence of the AM with the RM is demonstrated for the scope
of the AM. The three steps for demonstration of equivalence are:
— description of the AM and setting of the field of application;
— determination of the performance characteristics of the AM and calculation of the expanded uncertainty
where appropriate and check of compliance with the maximum expanded uncertainty allowed for the RM;
— check of repeatability and lack of systematic deviation of the AM in comparison with the RM.
Guidance on demonstration of equivalence is given in EN 14793 for stationary source emission measurement
methods and in the “Guide to the demonstration of equivalence of ambient air monitoring methods” for
[5]
ambient air quality measurement methods .
The field of application of an AM can partially or completely cover the field of application of the RM. However,
if it covers the fields of application of several RM (horizontal method), several evaluations of each RM are
needed, e.g. in the case of multi-component measurement methods like FTIR.
The definition of the field of application depends entirely upon the body specifying the AM and the knowledge
acquired during the development of the method. It is sometimes preferable to segment a field of application
rather than to attempt to validate an overly general method. In this case, a validation file for each field of
application is compiled.
7.3 Validation in the absence of certified reference materials
While metrological traceability of a measurement method to the SI is typically accomplished by use of
certified reference materials, in some situations a certified reference material might not be available. In
these situations, alternative approaches can include one or more of the following:
— inter-laboratory studies;
— recovery experiments using spiked samples;
— comparison with results obtained from another measurement method for the same measurand.
These alternatives do not necessarily establish metrological traceability.
8 Objective, design and documentation of a validation study
8.1 General
A validation study generally includes, at a minimum, the following aspects:
— objective(s) of the validation study (8.2);
— design of the validation study (8.3);
— documentation of the validation study (8.4).
NOTE Guidance on design and documentation of the validation study is also given in Eurachem documents.
8.2 Objective of a validation study
8.2.1 General
The initial step in the validation process is the analysis of the measurement objective (measurement task)
and the associated measurement method to identify the specific elements and associated requirements of
the measurement method. The validation concerns the following elements of the measurement method, for
example:
— sampling;
— sample preparation including e.g. sample transfer and storage;
— analysis;
— performance characteristics;
— determination of the result of measurement and the associated measurement uncertainty;
— documentation and reporting.
8.2.2 Purpose(s) for performing the measurement
Because the objective of validation is to demonstrate fitness for purpose in view of the measurement
objective, it is necessary to establish the purpose(s) for performing the measurement so that validation
activities can be properly designed to establish that the measurement method is fit for the intended
purpose(s). If the measurement method is to be fit for a single, narrow purpose, validation activities can be
more narrowly defined. If, however, the purposes are broad or numerous, or both, validation activities also
need to be sufficiently broad to address the full range of purposes for which the measurement method is
intended to be suitable. For example, validation activities for a measurement method intended to measure a
single air pollutant might not need to be as extensive as for a method intended to measure concentration of
multiple metals in an air sample.
8.2.3 Representative sampling
It is important to develop sampling strategies that result in samples that reflect the properties of interest
of the overall population being sampled. If this is not accomplished, even a reference method might not be
able to produce reliable results for decision making. Method validation needs to include consideration for
collecting representative samples.
8.2.4 Sample preparation
For many measurement methods, some preparation of the sample is necessary in advance of analysis.
8.2.5 Analysis
The analysis can be carried out in-situ or remotely in the laboratory.
Key considerations include assessment of the performance of the analytical method.
8.2.6 Performance characteristics
The performance characteristics of the measurement method determined in the validation process can
include:
— required detection sensitivity;
— limits of detection and quantification;
— selectivity (i.e. ability to measure the analyte of interest in the sample matrix);
— interferences;
— linearity;
— repeatability and reproducibility;
— measurement uncertainty;
— robustness.
8.2.7 Determination of the result of measurement and the associated measurement uncertainty
It is important that the procedures for the determination of the result of measurement and the associated
measurement uncertainty are fit for purpose and are giving correct results.
The measurement uncertainty expressed as an expanded uncertainty requires that the level of confidence
and the associated coverage factor are properly specified.
8.2.8 Documentation and reporting
It is important that the documentation and reporting procedures specified for the measurement method
meet the measurement objective.
8.3 Design of the validation study
The validation study is designed on the basis of the results obtained in 8.2.
The following factors are considered when designing a validation study:
— an understanding of how the method will be used and what is required to demonstrate fitness for
purpose;
— applicable requirements derived from either the measurement objective, legislation or regulation, or a
combination thereof;
— amount and types of data that need to be collected, and how that will be accomplished;
— reference materials to be used (see 7.1) or, in the absence of reference materials, an acceptable alternative
(see 7.3);
— time to complete the validation study;
— cost and financing of the validation study;
— whether samples can or cannot be replicated, and how that impacts the validation study;
— whether the true value is or is not known, and how that impacts the validation study.
The validation plan details the elements described above and specifies the organization plan and planning of
the validation experiments.
The organization plan includes the following tasks:
— coordination of the entire validation programme;
— specification of the number of experiments and the number of participants;
— selection of the participating testing laboratories and communication with them;
— designing the validation experiments:
— organizing an inter-laboratory test for the validation experiments in the laboratory;
— planning and preparation of the validation experiments in the field;
— cost calculations;
— reporting requirements.
The planning of the validation experiments covers the design of the laboratory and field tests. This includes
the specification of the number of testing laboratories and the number of tests to be performed with respect
to the subsequent statistical analysis of the data.
8.4 Documentation of the validation study
8.4.1 Report on the validation study
In the documentation of the results of the validation study including the underlying raw data the following
elements are included, if applicable:
— field of application;
— measurement method;
— measured component;
— measurand;
— cross-sensitivities;
— measuring range;
— performance characteristics and acceptance criteria;
— measurement uncertainty;
— validation range.
8.4.2 Storage of results of the validation study
Storage of the results of the validation study including the underlying raw data following the principles of
FAIR (findable, accessible, interoperable and reuseable) allows future use of these data.
9 Examples of validation procedures for specific types of measurement method
9.1 General
In the following sub-clauses, the key parameters of relevance for each type of measurement method (by
subcommittee) and references to the corresponding annexes for the additional details and examples are
presented for:
— stationary source emissions (9.2);
— workplace atmospheres (9.3);
— ambient atmospheres (9.4);
— meteorology (9.5);
— indoor air (9.6).
9.2 Stationary source emissions
9.2.1 General
A validation for emission measurement methods depends on the type of the measurement method, e.g.
manual or automated method, and on the compound of interest, e.g. gaseous or particulate measured
component.
General issues are described in 9.2.2 to 9.2.6.
Examples for the validation of emission measurement methods are presented in Annex A.
9.2.2 Manual measurement methods
The validation of the analytical method is essential for manual measurement methods. This usually includes
the use of calibration standards and samples in different concentrations and solutions containing interfering
substances, if appropriate, in inter-laboratory studies. It also includes stability tests of samples. These
tests are often carried out with samples prepared under controlled conditions and with known properties,
distributed to the participating testing laboratories. If the measurement method includes different analytical
methods, each of the analytical methods is included in the tests.
9.2.3 Automated measurement methods
The validation of the measuring principle of automated measurement methods includes the application of
corresponding analysers by use of test or calibration gases with known properties in different concentrations
and compositions. It also includes tests for cross-interferences caused by chemical interfering components
and physical influence quantities such as temperature and pressure. The tests are often carried out at
appropriate test benches. If the measurement method includes different measuring principles, each of the
measuring principle is included in the tests.
9.2.4 Test bench validation
Test bench experiments are carried out under controlled conditions with different pollutant concentrations,
different humidity (but without droplets) and different interfering substances. All participants use the
measurement method described e.g. in the draft standard. If the measurement method includes different
analytical methods or measuring principles, each of them is included in the tests. The evaluation of the test
results of the complete measurement method provides information on possible implications for the field tests.
9.2.5 Field test validation
Field tests with the complete measurement method are carried out at real industrial sites with e.g. different
influence parameters and waste gas abatement systems. If the measurement method includes different analytical
methods or measuring principles, each of them is included in the tests. The evaluation of the test results of the
complete measurement method provides information on the applicability of the method in the field.
9.2.6 Final evaluation
The final evaluation of the entire validation programme provides the results as per 8.4 for the specification
of the measurement method within the standardization work.
9.3 Workplace atmospheres
Annex B provides an example of method validation for workplace air measurements prepared by
ISO/TC 146/SC 2, Workplace atmospheres. Key aspects of the validation process for these measurement
methods include the following (see Figure B.1 for details):
— determination of basic properties of the substance to be analysed, including physical properties (e.g.,
gas/vapour, particulate, or semi-volatile) and any applicable occupational exposure limit values;
— selection of the analytical method and sampling method to be used;
— determination of the conditions for sampling, transport, and storage;
— determination of the sample preparation and analytical conditions;
— performance testing to determine analytical recovery, limits of detection and limits of quantification;
— calculation of the components of method uncertainty;
— compilation of the results as described in ISO 20581.
9.4 Ambient atmospheres
Currently none of the measurement methods elaborated by ISO/TC 146/SC 3 have been validated by intra-
laboratory or inter-laboratory testing. Details of selected measurement methods are provided in Annex C.
9.5 Meteorology
To date, ISO/TC 146/SC 5 meteorology standards have not been subject to intra-laboratory or inter-
laboratory precision testing validation. However, regarding wind meas
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