ISO 16000-44:2023

INTERNATIONAL ISO
STANDARD 16000-44
First edition
2023-12
Indoor air —
Part 44:
Test method for measuring perceived
indoor air quality for use in testing the
performance of gas phase air cleaners
Air intérieur —
Partie 44: Méthode d'essai pour mesurer la qualité de l'air intérieur
perçue à utiliser pour tester les performances des épurateurs d'air en
phase gazeuse
Reference number
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
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 Principle . 2
5 Apparatus, materials and sensory panel . 3
6 Test conditions .4
6.1 General . 4
6.2 Temperature and relative humidity . 5
6.3 Supply air quality and background concentration . 5
6.4 Air change rate . 5
6.5 Panel members . 5
6.6 Anterior space condition . 5
7 Preparation . 6
7.1 Preparation of the odour emission source(s) . 6
7.2 Preparation of air cleaner(s) . 6
8 Test method . 6
8.1 Test chamber method . 6
8.1.1 General . 6
8.1.2 Step 1: Measuring the perceived air quality without operating air cleaner(s) . 6
8.1.3 Step 2: Measuring the perceived air quality with operating air cleaner(s) . 7
8.1.4 Determination of perceived air quality . . 7
8.1.5 Instructions . 9
9 Efficiency . 9
10 Test report . 9
Annex A (informative) System for quality assurance and quality control .11
Annex B (informative) Examples of Test conditions for test chamber and air purifier .13
Annex C (normative) Test conditions for whole-body exposure in test chamber .14
Bibliography .16
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 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.
iv
Introduction
There is an increased interest in the development of air cleaners removing gaseous pollutants. Such air
cleaners are also called air purifiers. They have been marketed for reducing concentrations of gaseous
pollutants using different removal principles including among others physical and physicochemical
sorption or oxidation (mineralization).
The performance of gas phase air cleaners can be evaluated by their removal efficiency defined by the
ratio of concentration of pollutants downstream and upstream an air cleaner in the case of single pass
efficiency. Removal efficiency can also be obtained by determining the change of concentration in a
room where an air cleaner is in operation. Removal efficiency is consequently used to calculate clean
air delivery rate i.e. the equivalent airflow delivered by an air cleaner that does not contain pollutants
that were removed by an air cleaner (unpolluted air).
The removal efficiency is usually determined using a single pollutant or a mixture of up to a few
pollutants thus not capturing the entire spectrum of pollutants present. For this purpose, sensory
assessment of air quality made by human subjects can be made. The ratings of air quality as perceived
by people are not normally used (seldom) to assess the removal efficiency of air cleaners although,
based on them, ventilation requirements prescribed by standards in many parts of the world have been
determined. Because measurements of chemical compounds will seldom capture all pollutants and
because no models exist to describe how they will be perceived by building occupants, examining the
effect of the air quality of an air cleaner as perceived by humans [so-called perceived air quality (PAQ)]
seems relevant and should be considered as a supplementary method to chemical measurements.
There are different methods used to determine PAQ. The two most frequently used are the assessments
of odour intensity of the air and acceptability of air quality; the latter can be used to determine the
percentage of dissatisfied people. The measurements are made by human subjects (sensory panels)
who use their olfactory sense to determine PAQ. Specially trained subjects (so-called trained panels)
and untrained subjects (so-called untrained panels) can be used.
Historically, when ventilation requirements were determined in the 1930s by Yaglou and his colleagues,
odour intensity was used to determine PAQ based on which ventilation requirements were prescribed.
Yaglou’s results were subsequently used in standards and handbooks in many parts of the world have
been fundamentally based on his work. In the later research in the 1980s among others by Fanger and
his colleagues, the ratings of acceptability were used to describe PAQ and ventilation requirements
prescribed in the standards were subsequently revised.
Considering the above, there is a need for a standard to assess the performance of gas phase air
cleaners based on sensory ratings of air quality so that it can be compatible with the current ventilation
standards. This document describes a test method that can be used to evaluate the performance of air
cleaners that primarily remove gaseous pollutants from the air based on the ratings of PAQ.
v
INTERNATIONAL STANDARD ISO 16000-44:2023(E)
Indoor air —
Part 44:
Test method for measuring perceived indoor air quality for
use in testing the performance of gas phase air cleaners
1 Scope
This document specifies a laboratory test method for measuring perceived air quality using human
subjects that can be used for assessing the performance of air cleaners removing gas-phase pollutants.
The method describes the performance of gas-phase air cleaners with respect to removal of pollutants
that can be sensed by human subjects.
The method has a reference to sensory tests specified in ISO 16000-28.
Air cleaners removing particles and aerosols (mechanical or electronic filters) can also remove
pollutants responsible for sensory response. The method described in this document does not apply to
testing of these air cleaners.
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 16000-3, Indoor air — Part 3: Determination of formaldehyde and other carbonyl compounds in indoor
and test chamber air — Active sampling method
ISO 16000-6, Indoor air — Part 6: Determination of organic compounds (VVOC, VOC, SVOC) in indoor and
test chamber air by active sampling on sorbent tubes, thermal desorption and gas chromatography using
MS or MS FID
ISO 16000-9, Indoor air — Part 9: Determination of the emission of volatile organic compounds from
building products and furnishing — Emission test chamber method
ISO 16000-11, Indoor air — Part 11: Determination of the emission of volatile organic compounds from
building products and furnishing — Sampling, storage of samples and preparation of test specimens
ISO 16000-28, Indoor air — Part 28: Determination of odour emissions from building products using test
chambers
ISO 16017-1, Indoor, ambient and workplace air — Sampling and analysis of volatile organic compounds by
sorbent tube/thermal desorption/capillary gas chromatography — Part 1: Pumped sampling
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/
3.1
acceptability
parameter used to describe indoor air quality as it is perceived by people
Note 1 to entry: Acceptability describes overall perception of the quality of air indoors taking into account
intensity and hedonic character.
Note 2 to entry: Acceptability can be assessed with the dichotomous or continuous visual-analogue scale; the
latter is frequently used. The end points are clearly acceptable and clearly unacceptable.
3.2
air cleaner
apparatus that reduces concentration of indoor pollutants using active or passive method
Note 1 to entry: An air cleaner in this document is understood as an electrically-powered device that is basically
built of components having the ability to capture gas-phase pollutants and a fan drawing the air through it.
Note 2 to entry: An air cleaner is the device that can be installed either in a room or in a duct, or both.
3.3
odour intensity
parameter used to describe the intensity of odour caused by indoor pollutants as it is perceived by
people
Note 1 to entry: Odour intensity is assessed using a continuous scale having end points “no odour” and
“overpowering odour” and four intermediate equally distanced levels: “slight odour”, “moderate odour”, “strong
odour” and “very strong odour”.
Note 2 to entry: Odour intensity can also be measured using other methods than described in Note 1 to entry.
ISO 16000-28 provides a method using the perceived intensity with the unit pi. The method presented in Note 1
to entry and pi method are well correlated.
3.4
panel
group of people (assessors or subjects) performing sensory evaluation of air quality (3.6)
3.5
panel member
member of a panel (3.4) performing sensory evaluation of air quality (3.6)
3.6
perceived air quality
parameter used to describe the quality of indoor air as perceived by people and evaluated in terms of
either acceptability (3.1) or odour intensity (3.3), or both
4 Principle
The aim of this document is to describe the method for measuring the perceived air quality indoors when
gas-phase air cleaner(s) is(are) in operation. The perceived air quality is determined using subjective
evaluations of either acceptability or odour intensity, or both. The air assessed by a panel is presented
via a sniffing device (a funnel). The perceived air quality is used to determine the removal efficiency of
an air cleaner(s). If the equivalent measurement accuracy can be guaranteed, the alternative method
can be used where panel members directly enter the test chamber to perform sensory evaluations.
Follow the method specified in Annex C.
The assessments are made in a test chamber having a general room volume size. The test method
consists of two steps:
a) a sensory test without air cleaner(s), and
b) a sensory test with an air cleaner(s).
Before performing a sensory test using the described method, it must be documented that no
compounds are present in the air that are toxic, carcinogenic or harmful to people performing sensory
evaluations at the inhalation doses (concentration and exposure time) received during testing. Fulfilling
this requirement will comply with general requirements set by the ethical committees worldwide.
5 Apparatus, materials and sensory panel
5.1 Test chamber. A space large enough to room air cleaner, pollution sources and people -
volunteer(s) staying inside for the purpose of emitting pollutants (a source of human bioeffluents) (see
Figure 1) should be used as a test chamber. The room shall guarantee the same conditions as the test
chamber specified in ISO 16000-9.
Test room shall have a suitable environmental control system to maintain a constant temperature and
humidity, and provide ventilation with outdoor (unpolluted) air.
The room shall be kept clean and be characterized as low–polluting, i.e. the emissions of pollutants
inside the room should be kept as low as possible to ensure proper background reference. The removal
capacity of the test chamber for gaseous pollutants through e.g. adsorption should be sufficiently low
not to compete with an air cleaner being tested.
The test chamber shall be equipped with a fan ensuring that the air is well mixed within the entire
volume thus complying with relevant specifications and requirements of ISO 16000-9. The mixing of
the air shall be documented. No air shall be allowed to circulate from the air exhaust to air supply
terminals.
a) Test room for a standalone air cleaner b) Test room for a duct air cleaner

c) Test room for a duct air cleaner (single-pass condition)
Key
1 test chamber 7 tube or duct
2 clean and temperature/humidity conditioned air 8 sniffing device, complying with relevant specifications
supply inlet and requirements of ISO 16000-28
3 exhaust outlet 9 front/anterior space in which human panel enter
4 emission source 10 doors where panel enters
5 an air cleaner 11 in duct air cleaner
6 mixing fan
Figure 1 — Schematic diagram of a test room
5.2 Anterior space. Front/anterior space in which human panel enter shall guarantee the same
temperature, relative humidity and background concentration conditions as the test chamber.
5.3 Temperature and humidity. Temperature in the chamber shall be maintained at 23 °C (±1 °C).
Relative humidity in the chamber shall be maintained at 50 % (±10 %).
5.4 Air flow meter shall be installed at the inlet or the outlet of the test chamber to measure and
monitor the air flow rate to or air exchange rate in the test chamber. Air flow meter should also be
installed to measure the air flow rate from sniffing device. Air flow rate shall be regularly recorded.
5.5 Odour emission source(s) shall be building material(s) or product(s), permeation tube(s), and/or
human volunteer(s) that steadily and constantly emit gaseous pollutants. They shall be placed/installed
in the test chamber. Odour emission source(s) that result at least in the moderate odour intensity is
desirable under the Step 1 test condition specified in 8.1.2.
5.6 Air cleaner. A stand-alone air cleaner shall be placed and operated in the test chamber. The
in-duct air cleaners shall be installed in the duct with fan and then placed in the test chamber. When
testing under single-pass conditions, the sniffing device should be installed in the duct after passing
through the in-duct air cleaner.
5.7 Air sampling devices. Sampling devices used to sample the inlet and outlet air of the test
chamber shall comply with the specifications of ISO 16000-3 and ISO 16000-6, respectively. When the
air is sampled from the inlet, it shall be ensured that the supply air flow rate remains constant.
5.8 Analytical instrument. For determination of carbonyl compounds and volatile organic
compounds (VOCs), a high-performance liquid chromatograph (HPLC) and/or a gas chromatograph
(GC) shall be used as specified in ISO 16000-3, ISO 16000-6, and ISO 16017-1. Alternative devices with
an equal or better accuracy can be used.
5.9 Sensory panel. The panel selection shall comply with the specifications of ISO 16000-28.
6 Test conditions
6.1 General
These test conditions apply at atmospheric pressure conditions. Temperature, relative humidity,
background pollution levels, and air flows apply both for the test and anterior space.
6.2 Temperature and relative humidity
The temperature in the test chamber should be set to 23 °C (±1 °C), and relative humidit
...