ISO 16000-41:2023
(Main)Indoor air — Part 41: Assessment and classification
Indoor air — Part 41: Assessment and classification
This document specifies a procedure for the assessment of the indoor air quality that is valid for all interior rooms in residential and non-residential buildings with natural or mechanical ventilation, in which people do not only stay temporarily. This document is applicable to indoor environments as defined in ISO 16000-1. The assessment of working materials in workrooms or workplaces in buildings, that are subject to statutory occupational safety specifications, are excluded from this document. In these rooms, only air constituents that do not originate from working materials can be assessed according to this document. It is not possible to define classes with exact values for the individual pollutants, as the corresponding limit and guide values differ in individual countries. In addition, the values relate to different observation periods. Aspects concerning electromagnetic fields, noise and vibrations and their effect on the indoor air quality are not the object of this document. The classification of further consequences and measures, such as organisational steps, structural engineering measures, renovation proposals, further human medicine appraisals and the like, are not the object of this document. NOTE This document applies to of all types of indoor environments occupied by all kinds of persons, including regular users, clients and workers.
Air intérieur — Partie 41: Évaluation et classification
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16000-41
First edition
2023-08
Indoor air —
Part 41:
Assessment and classification
Air intérieur —
Partie 41: Évaluation et classification
Reference number
ISO 16000-41:2023(E)
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ISO 16000-41:2023(E)
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ISO 16000-41:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
4.1 Procedure . 2
4.2 Parameters . 3
5 Indoor air quality . 3
6 Quality classes . 3
7 Criteria for the definition of the quality classes . 4
7.1 General . 4
7.2 Main parameters. 4
7.3 Secondary parameters . 5
8 A ss e ss ment pla n .6
8.1 Overview . 6
8.2 Documentation and reports . 7
8.3 Purpose of measurements . 8
8.3.1 Possible reasons . 8
8.3.2 Concretisation of assessment. 8
8.4 Preliminary survey . 8
8.4.1 General . 8
8.4.2 Basic investigation . 9
8.4.3 Local inspections . 9
8.4.4 Conditions for the omission of the measurement of parameters . 10
8.5 Investigation plan . 10
8.5.1 General . 10
8.5.2 Normative specifications . 10
8.5.3 Determination of sampling points . 11
8.5.4 Utilization of the interior room . 11
8.5.5 Seasonal fluctuations and ventilation . 11
8.5.6 Complementary outside air measurements .12
8.6 Investigation . 12
8.7 Report .12
8.8 Division in quality classes . 12
Annex A (informative) Quality classes for main parameters.14
Annex B (informative) Standards for the preliminary survey and the design of investigation
plans .21
Bibliography .24
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ISO 16000-41:2023(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 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 6,
Indoor air.
A list of all parts in the ISO 16000 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.
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ISO 16000-41:2023(E)
Introduction
In our society, privately and professionally, people stay indoors most of the day. Therefore, the quality of
the indoor air is very decisive for the quality of life and health. This especially applies to small children,
sick people and other vulnerable groups of persons.
Numerous scientific studies verify the positive effects of good indoor air on the overall performance
during learning (e.g. in kindergartens and schools) and working. A consequence of improved indoor air
quality can be, for example, reduced sickness rates and absenteeism.
The entitlement to high-quality indoor air does not contradict economical aspects of energy- and cost-
efficiency. Improvements in the quality of indoor air are achievable with simple measures, for example,
change of behaviour patterns.
This document describes a procedure to classify the air quality of indoor spaces using quality classes.
These quality classes enable the allocation of the room air to a high, medium or low quality. The quality
classes are based on criteria for physical, chemical and biological parameters according to the state
of science and research. These criteria can be both concentration values in the room air (e.g. with
formaldehyde) as well as sensory and other findings in the room itself (e.g. with mould). The basis for
classifying a measured value of a parameter in a quality class is the definition of class boundaries for
quality classes A to C by national institutions, using guide values from national guidelines, European
and international publications and trade literature.
The most frequent pollutant sources indoors are human activities (e.g. domestic-, hobby- and cleaning
activities, tobacco smoke), combustion processes as well as building materials, furnishings and interior
design materials. The exception is the radioactive inert gas radon, which mostly originates from the
geological subsoil and enters the interior spaces via leaks in the building envelope.
A variety of substances can emit into the indoor air from the most diverse pollution sources. For
this reason, the single analysis of a source or pollutant cannot be used as a substitute for an overall
assessment of the indoor air. A meaningful assessment of the indoor air is only achievable by an overall
assessment of all pollutant sources and substances.
This document is intended for specialists who deal with the assessment of indoor air in the course
of planning, construction, operation and use of buildings (e.g. indoor-experts, architects, specialist
planners of trades, building owners, building developers and contracting authorities, maintenance
engineers, lessors). Also included are producers and distributors of products, that are installed and/or
operated indoors (e.g. building products), and possible users.
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INTERNATIONAL STANDARD ISO 16000-41:2023(E)
Indoor air —
Part 41:
Assessment and classification
1 Scope
This document specifies a procedure for the assessment of the indoor air quality that is valid for all
interior rooms in residential and non-residential buildings with natural or mechanical ventilation, in
which people do not only stay temporarily.
This document is applicable to indoor environments as defined in ISO 16000-1.
The assessment of working materials in workrooms or workplaces in buildings, that are subject to
statutory occupational safety specifications, are excluded from this document. In these rooms, only air
constituents that do not originate from working materials can be assessed according to this document.
It is not possible to define classes with exact values for the individual pollutants, as the corresponding
limit and guide values differ in individual countries. In addition, the values relate to different
observation periods.
Aspects concerning electromagnetic fields, noise and vibrations and their effect on the indoor air
quality are not the object of this document. The classification of further consequences and measures,
such as organisational steps, structural engineering measures, renovation proposals, further human
medicine appraisals and the like, are not the object of this document.
NOTE This document applies to of all types of indoor environments occupied by all kinds of persons,
including regular users, clients and workers.
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 11665-8, Measurement of radioactivity in the environment — Air: radon-222 — Part 8: Methodologies
for initial and additional investigations in buildings
ISO 16000 (all parts), Indoor air
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
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ISO 16000-41:2023(E)
3.1
building product
product or building kit, that is manufactured or brought into circulation, to be installed permanently
in buildings or parts of buildings and whose performance affects the performance of the building with
regard to the basic requirements on buildings
[23]
[SOURCE: EU-BauPVO, Article 2 (1) ]
3.2
assessment value
value obtained from an assessment
Note 1 to entry: The assessment value can be an individual measured value, the arithmetic mean of individual
measured values or the result of a continuous measurement over a particular time period. In the case of carbon
dioxide (CO ), the assessment value is a statistical evaluation of the individual measured values.
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3.3
assessment period
period during which the investigation of the indoor air takes place
Note 1 to entry: The assessment period is adapted to the parameter to be assessed and the measuring task and
linked to certain usage conditions.
3.4
emission
release of chemicals, vibration and radiation to the environment
Note 1 to entry: The emission of air constituents can be specified as mass flow. In relation to building products
(3.1), the mass flow can be related to area, length, mass, volume or component.
Note 2 to entry: The terms “emission” and “release” basically have the same meaning.
3.5
main parameter
parameter which, during an overall assessment, is taken into consideration without fail
3.6
secondary parameter
parameter that is also taken into consideration for the overall assessment, if references to its relevance
exist in the preliminary survey
3.7
guide value
default value that serves as a comparative value for the assessment
Note 1 to entry: Specific guide values for interior rooms are defined, for example, by the WHO and national/
professional institutions.
4 General
4.1 Procedure
The procedure for the assessment of the indoor air quality consists of the following steps:
a) preliminary survey;
b) investigation plan;
c) investigation;
d) documentation;
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ISO 16000-41:2023(E)
e) expert opinion.
When this document is applied, it should be taken into consideration that the concentrations of
substances in the room air can fluctuate greatly: spatially, time-related and usage-specific. This is
particularly dependent on ventilation, the building services and the individual user behaviour.
Individual results of certain parameters cannot sufficiently characterize the indoor air, therefore the
overall assessment described in this document is necessary in order to obtain a comprehensive and
differentiated picture of the room air situation.
An investigation of buildings for pollutants shall be carried out in accordance with ISO 16000-32.
4.2 Parameters
Chemical, biological and physical parameters play a role in the assessment of the indoor air.
— chemical parameters and particles: gases, volatile and hardly volatile organic and inorganic
compounds, fibres, dusts, dust constituents and odours;
— biological parameters: fungi, bacteria, viruses, pollen and other allergens (e.g. animal epithelia,
insects/insect compounds, mites, mite excrement, plant parts/fibres);
— physical parameters: room air and environment surface temperatures, operative temperature, air
humidity, air velocity, lighting, sounds and noise, electromagnetic fields and charged particles.
In the context of this document, only selected chemical and biological parameters are dealt with. The
room air temperature and the humidity should be regarded as supplementary physical parameters.
NOTE Physical parameters are dealt with in, for example, ISO 7730.
5 Indoor air quality
For the assessment of the indoor air according to this document, a classification of the room air
quality into three quality classes A (high), B (medium) and C (low) is performed based on prescribed
main parameters (see 7.2). In addition, further secondary parameters (see 7.3) should be taken into
consideration, if necessary.
The class limits of the quality classes are defined by:
— guide values in the sense of maximum permissible concentrations in the room air (e.g. with
formaldehyde) or distributions of measured values (e.g. with carbon dioxide CO ),
2
— sensory findings in the room itself (e.g. with mould, odours).
The use of a questionnaire can also contribute to the assessment of a room.
6 Quality classes
Table 1 provides an overview of the quality classes and describes the requirements on the room air
quality on which these classes are based. The designations and descriptions of the requirements
according to Table 1 are only partly applicable for the parameter “Mould – microbial infestation”.
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ISO 16000-41:2023(E)
Table 1 — Indoor air quality classes
Quality class Designation Description
A High room air quality Room air with low substance concentrations
B Medium room air quality Room air with average substance concentrations
C Low room air quality Room air with above-average substance concentrations
Lowest air quality class not fulfilled Substance concentrations above the class limits of quality class C
If any main criteria do not permanently fulfil even quality class C, the indoor air shall not be classified
but is considered to be “outside all quality classes”.
During the course of an assessment, the need for different quality classes can arise for a specific interior,
depending on which parameter is considered.
For the assessment, it shall be taken into consideration that many building products show a significant
decrease of their emissions, especially in the first days and weeks after their manufacturing. A
meaningful holistic assessment of the room air condition in the sense of this document is only possible
in an actual usage stage.
7 Criteria for the definition of the quality classes
7.1 General
The basis for classifying a measured value of a parameter in a quality class is the definition of class
boundaries for quality classes A to C. The limits of the quality classes can be defined on the basis of guide
values from national guidelines and European and international, publications and trade literature. For
the parameter "Mould – Microbial Infestation", in addition the condition of the room with regard to
mould infestation is adjudged.
7.2 Main parameters
Parameters most frequently giving rise for complaints due to the quality of indoor air are defined as
main parameters in this document.
In the framework of the overall assessment, the expert shall assess all these main parameters, however
a measurement of every parameter is not always necessary (see 8.4.4).
Table 2 lists the main parameters as well as the corresponding clauses in annexes of this document.
Table 2 — Main parameters
Parameter Clause
Formaldehyde A.2
Volatile organic compounds (VOC) A.3
Radon A.4
Carbon dioxide A.5
Mould - microbial infestation A.6
Odour A.7
Fine dust (PM1, PM2.5, PM10), ultrafine particles (UFP) —
The criteria for the parameter carbon dioxide were derived from considerations of comfort as well as the
users´ cognitive performance. Carbon dioxide levels are also used as an indicator for the concentration
of emissions of the user or animals by breathing and body effluence into indoor air.
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ISO 16000-41:2023(E)
The appearance of mould is usually associated with the presence of filamentous fungi and yeast. Often
bacteria are also present. In the case of air measurements, only the concentration of mould and bacteria
is usually recorded.
The physical parameters “room air temperature” and “relative humidity” shall be recorded separately in
the representation of the measurement results, because they influence the concentrations of pollutants
in the room air and are frequently associated by users with an inadequate indoor air quality.
7.3 Secondary parameters
Secondary parameters are used, when there are indications of an occurrence of substance concentrations
with a negative impact on the indoor air quality. In these cases, the investigation program shall be
complemented with these secondary parameters. The consideration of secondary parameters shall be
identified and justified accordingly in the overall assessment.
No quality classes are defined in this document for secondary parameters. That does not mean
that quality classes cannot be defined. For some of the compounds, no effectiveness threshold or
concentration can be specified, under which no health-related effects are to be expected.
The evaluation of secondary parameters is at the discretion of the expert.
In summary, secondary parameters include factors such as
— ammonia and heavy metals (e.g. mercury),
— asbestos,
— carbon monoxide,
— biocides (e.g. PCP, lindane),
— CMR substances in general,
— synthetic mineral fibres,
— nicotine,
— polychlorinated biphenyls (PCB),
— polychlorinated dioxins and furans (PCDD/PCDF),
— polycyclic aromatic hydrocarbons (PAH),
— sulfur dioxide,
— nitrogen oxides,
— other organic compounds besides VOC (VVOC, SVOC, MVOC), and
— parameters: fungi, bacteria, viruses, pollen and other allergens (e.g. animal epithelia, insects/insect
compounds, mites, mite excrement, plant parts/fibres).
ISO 16000-1:2004, Annex C contains a list of sources of air impurities in interior rooms and the
substances or substance groups emitted from them, that shall be used as a basis for the determination,
investigation and assessment of secondary parameters.
Before the implementation of measurements of identified hazardous substances in the room, the
investigation of possible sources in buildings is recommended.
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ISO 16000-41:2023(E)
8 Assessment plan
8.1 Overview
The overall assessment of the indoor air of an individual room or a building with multiple rooms shall
take the individual steps of the assessment procedure into account, as listed in Table 3.
Table 3 — Phases of an overall assessment
Phase 1: Finding
Compilation of the information and documents required for the planning of an investigation
Preliminary survey
(e.g. previous test results, medical findings, data sheets)
Decision, whether the sampling or investigation is to be carried out on-site; definition of the
Investigation plan
parameters to be considered in the planning of an investigation
Investigation Implementation of the planned investigation or sampling and evaluation of the samples
Documentation of the measurement procedure, measuring results and framework conditions
Documentation
of the investigation
Phase 2: Assessment
Classification in Assessment of the room air quality based on the quality classes according to this docu-
quality classes ment
Figure 1 shows the individual steps of Table 3 and the documents resulting therefrom.
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ISO 16000-41:2023(E)
Figure 1 — Procedure and steps of an assessment of the indoor air
8.2 Documentation and reports
The documentation shall include the findings and the assessment.
The introduction of the documentation shall include the aims and objectives of the indoor air
assessment and the reason why the assessment is performed. Subsequently every individual step shall
be documented separately in the report according to Figure 1 (preliminary survey, investigation plan,
sampling report and representation of the measurement results).
The conclusions from the results of the findings and the classification in quality classes shall be
documented in the form of a report.
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ISO 16000-41:2023(E)
8.3 Purpose of measurements
8.3.1 Possible reasons
An assessment of the room air of interior rooms can be triggered for numerous reasons. Possible
reasons are, for example:
a) Adherence to predetermined values: The adherence to predetermined values is verified. This can,
for example, be in connection with the certification of building performance or assessments of the
reasonableness of odours.
b) Acquisition of information through measurements: The background concentration, or a
concentration before, during and after a renovation measure is checked, based on e.g. control-,
work-accompanying- and release measurements. Likewise, such measurements can be performed
in the course of research studies, for which the parameters are usually predetermined.
c) Insufficient quality of the indoor air: There are general complaints by room users concerning a
room air quality perceived as poor. These complaints can be, for example, in connection with an
unpleasant smell.
d) Impairment of the health of room users: There are indications for an impairment of the health of
room users due to pollutants or physical parameters in the indoor air. These indications can be, for
example, specific symptoms in the respiratory tract of room users.
These various reasons can exist individually or also jointly and in each case result in different methods
of procedure of the respective competent
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