SIST ISO 4226:2026

• Abstract:

  This document establishes the terms and symbols used to report the results of air quality measurements.; NOTE General guidance on the International System of Units is given in the ISO 80000 series.

• Status: Published
• Public Enquiry End Date: 19-Jul-2026
• Publication Date: 16-Sep-2026
• ICS: 01.060 - Quantities and units
• ICS: 13.040.01 - Air quality in general
• Technical Committee: KAZ - Air quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Sep-2026
• Due Date: 15-Nov-2026
• Completion Date: 17-Sep-2026
• Ref Project: ISO 4226:2026 - Air quality — General aspects — Quantities and associated units for reporting results of air quality measurements

• Replaces: SIST ISO 4226:2013 - Air quality - General aspects - Units of measurement
• Effective Date: 01-Oct-2026

SIST ISO 4226:2026 is the SIST publication of ISO 4226:2026 for air quality reporting. It specifies the terms, symbols and associated units used to report results of air quality measurements so results can be compared consistently across gases, vapours and particles.

What does SIST ISO 4226:2026 specify?

SIST ISO 4226:2026 specifies how to name and write the quantities and units used when reporting air quality measurement results. Its focus is reporting language, not measurement methods, so it helps people present results in a shared format.

The document is organized into Scope, Normative references, Terms and definitions, and Quantities and associated units. The technical content is concentrated in Clause 4, with Table 1 for quantities and units and Table 2 for prefixes.

What are the key requirements of SIST ISO 4226:2026?

• Clause 4.1 says the terms and symbols in Table 1 should be used when reporting air quality measurements. In practice, this gives reporters a common vocabulary for results, which reduces confusion between laboratories, sites and countries.

• Clause 4.1 also points other units to the general principles in ISO 80000. That matters when a report needs a unit that is not listed in Table 1, because the unit still has to follow standard unit rules.

• Clause 4.2 groups quantities by application area: general quantities, stationary source emissions, workplace atmospheres, ambient air quality, meteorology, indoor air, statistics and other reporting terms. In practice, users should choose the quantity set that matches the measurement context instead of reusing a familiar term in the wrong area.

• Clause 4.2 says measurement uncertainty is always expressed in the unit of the measurand, and relative measurement uncertainty is usually expressed as a percentage of the measured value. This makes uncertainty statements directly comparable with the reported result.

• Clause 4.2 allows the same symbol to be used for different quantities when the unit, and if needed indices, remove ambiguity. The document also gives recommended indices. In practice, this lets one symbol serve several meanings, but only if the report makes the distinction clear.

• Clause 4.2 notes that some quantities are dimensionless, such as sample size or mole fraction, and warns that language-specific units such as ppm or ppb can cause confusion. If such units are used, the report has to explain what they mean.

• Clause 4.3 explains the use of prefixes for decimal multiples and submultiples of units. This helps keep numbers readable, for example by avoiding very long decimal strings in concentration or pressure results.

• Clause 4.2 also covers statistical quantities and other reporting terms such as detection and quantification limits, mean value and derivative. In practice, this gives a shared notation for uncertainty work, data analysis and reporting limits.

Who uses SIST ISO 4226:2026?

SIST ISO 4226:2026 is used by people who prepare, review or compare air quality measurement reports. That includes laboratories, environmental monitoring teams, occupational hygiene and workplace atmosphere specialists, indoor air assessors, and engineers dealing with stationary source emissions or meteorological reporting.

Quality managers and buyers use SIST ISO 4226:2026 when they need to check that data will be reported with the right quantity names, symbols and units. It is especially useful when results must be compared between sites, organizations or countries.

What changed in SIST ISO 4226:2026 from the previous edition?

SIST ISO 4226:2026 is the fourth edition and replaces ISO 4226:2007. The stated changes are:

• Clause 3 has been added.
• Clause 4 now includes more information on the use of quantities, units and prefixes.
• Table 1 has been reorganized and symbols for quantities have been added.
• Table 2 on prefixes has been added.

Which standards are used with SIST ISO 4226:2026?

• ISO 80000 (all parts), Quantities and units - provides the general principles for quantities and units that Clause 4 refers to, including guidance for unit use and the International System of Units.

What does the SIST ISO 4226:2026 document contain?

SIST ISO 4226:2026 contains a short front matter, Clauses 1 to 4, Table 1 and Table 2. Table 1 is the main technical table and pairs quantities with symbols and units across general air quality reporting, source emissions, workplace atmospheres, ambient air quality, meteorology, indoor air, statistics and other terms.

Clause 4.2 explains how to handle repeated symbols, recommended indices and dimensionless quantities so reports stay unambiguous. Clause 4.3 explains how prefixes are used to form practical decimal multiples and submultiples of units.

The text also includes examples showing how prefix choice affects the readability of reported values. In practice, this supports cleaner measurement reports, easier data comparison and more consistent notation across air quality work.

SLOVENSKI STANDARD
01-oktober-2026
Nadomešča:
SIST ISO 4226:2013
Kakovost zraka - Splošni vidiki - Veličine in enote za poročanje o rezultatih
meritev kakovosti zraka
Air quality - General aspects - Quantities and associated units for reporting results of air
quality measurements
Qualité de l'air - Aspects généraux - Grandeurs et unités associées pour consigner les
résultats des mesurages de la qualité de l'air
Ta slovenski standard je istoveten z: ISO 4226:2026
ICS:
01.060 Veličine in enote Quantities and units
13.040.01 Kakovost zraka na splošno Air quality in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

International
Standard
ISO 4226
Fourth edition
Air quality — General aspects —
2026-09
Quantities and associated units
for reporting results of air quality
measurements
Qualité de l'air — Aspects généraux — Grandeurs et unités
associées pour consigner les résultats des mesurages de la qualité
de l'air
Reference number
© ISO 2026
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quantities and associated units . 1
4.1 General .1
4.2 Use of quantities and units .1
4.3 Use of prefixes .2

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,
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 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)
patent(s) which may be required to implement this document. However, implementers are cautioned that
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
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 4, General
aspects.
This fourth edition cancels and replaces the third edition (ISO 4226:2007), which has been technically
revised.
The main changes are as follows:
— Clause 3 has been added;
— information regarding the use of quantities, units and prefixes has been added to Clause 4;
— Table 1 has been reorganized and symbols for quantities have been added;
— Table 2 on prefixes has been added.
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
The International Standards on the general aspects of air quality include the standardization of methods for
the measurement of gases, vapours and particles. In order to enable results to be compared either within or
between countries, it is reasonable to use only a minimal number of symbols and units that have been agreed
upon to report the results of measurements and other relevant information so that sound conclusions can be
drawn.
v
International St
...

International
Standard
ISO 4226
Fourth edition
Air quality — General aspects —
2026-09
Quantities and associated units
for reporting results of air quality
measurements
Qualité de l'air — Aspects généraux — Grandeurs et unités
associées pour consigner les résultats des mesurages de la qualité
de l'air
Reference number
© ISO 2026
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quantities and associated units . 1
4.1 General .1
4.2 Use of quantities and units .1
4.3 Use of prefixes .2

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,
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 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)
patent(s) which may be required to implement this document. However, implementers are cautioned that
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
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 4, General
aspects.
This fourth edition cancels and replaces the third edition (ISO 4226:2007), which has been technically
revised.
The main changes are as follows:
— Clause 3 has been added;
— information regarding the use of quantities, units and prefixes has been added to Clause 4;
— Table 1 has been reorganized and symbols for quantities have been added;
— Table 2 on prefixes has been added.
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
The International Standards on the general aspects of air quality include the standardization of methods for
the measurement of gases, vapours and particles. In order to enable results to be compared either within or
between countries, it is reasonable to use only a minimal number of symbols and units that have been agreed
upon to report the results of measurements and other relevant information so that sound conclusions can be
drawn.
v
International Standard ISO 4226:2026(en)
Air quality — General aspects — Quantities and associated
units for reporting results of air quality measurements
1 Scope
This document establishes the terms and symbols used to report the results of air quality measurements.
NOTE General guidance on the International System of Units is given in the ISO 80000 series.
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 unda
...