ISO 16000-42:2023
(Main)Indoor air — Part 42: Measurement of the particle number concentration by condensation particle counters
Indoor air — Part 42: Measurement of the particle number concentration by condensation particle counters
This document specifies the measurement methods and strategies for determining the total number of airborne particles per unit volume of air indoor, using a condensation particle counter (CPC) for particles approximately between 10 nm to 3 µm. NOTE As the particle number concentration is usually dominated by the ultrafine particle (UFP) fraction, the obtained result can be used as an approximation of the UFP concentration. Quality assurance, determination of the measurement uncertainty and minimal reporting information are also discussed in this document. This document is applicable to indoor environments as specified in ISO 16000-1. This document does not address the determination of bioaerosols or the chemical characterization of particles. Nevertheless, some bioaerosols can be detected by the CPC and then contribute to the measured count of particles.
Air intérieur — Partie 42: Mesurage de la concentration en nombre de particules au moyen de compteurs de particules à condensation
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16000-42
First edition
2023-08
Indoor air —
Part 42:
Measurement of the particle number
concentration by condensation
particle counters
Air intérieur —
Partie 42: Mesurage de la concentration en nombre de particules au
moyen de compteurs de particules à condensation
Reference number
ISO 16000-42:2023(E)
© ISO 2023
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ISO 16000-42:2023(E)
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ISO 16000-42:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Sources of airborne particles . 4
5.1 General . 4
5.2 Combustion of organic material . 5
5.3 Smoking . 5
5.4 Cooking . 5
5.5 Particle formation — Formation of secondary organic aerosol . 5
5.6 Outdoor air . 5
5.7 Other sources . 5
6 Dynamics of ultrafine particles indoors . 6
6.1 General . 6
6.2 Infiltration and exfiltration . 7
6.3 Deposition . 7
6.4 Particle formation, phase transition and coagulation . 7
7 Principle of measurement .8
7.1 General . 8
7.2 Working fluid . 8
7.3 Minimal detection size . 10
7.3.1 General . 10
7.3.2 Optical detection after enlargement . 10
7.3.3 Particle size distribution. 11
7.4 CPC minimal requirement . 11
7.5 General sampling requirements and recommendations .13
8 Measurement strategy .13
8.1 General .13
8.2 Average room concentration . 14
8.2.1 General . 14
8.2.2 Resting state without activity . 15
8.2.3 Resting state with equipment activity . 15
8.2.4 Active state .15
8.3 Source investigation/identification . 15
8.4 Infiltration from outdoor or connecting rooms . 16
8.5 Measurement in vehicle cabins . 17
8.6 Success of control and mitigation measures . 17
9 Quality assurance and uncertainty evaluation .17
9.1 General . 17
9.2 Instrument parameters . 18
9.3 CPC’s settings check . 18
9.4 Performance check, zero check or leak check . 18
9.5 Uncertainty . 19
10 Evaluation and reporting of the results .19
Annex A (informative) Examples of particle number concentrations encountered during
room user activities .21
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ISO 16000-42:2023(E)
Annex B (informative) Determination of the particle number size distribution of indoor
aerosol using a differential mobility aerosol spectrometer .22
Annex C (informative) Water-CPCs .25
Annex D (informative) Checklist to collect information useful for interpreting indoor
measurement of particle number concentration .27
Bibliography .31
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ISO 16000-42:2023(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
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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
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database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
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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 16000-42:2023(E)
Introduction
People spend most of their day indoors where they are exposed to various sources of particles. Such
particles can be dust particles, particles from combustion processes such as candles, cooking and
fireplaces. Particles can also be emitted by do-it-yourself activities and the operation of electrical
equipment such as printers. Classical building envelope materials are not efficient to prevent particle
transport between indoor and outdoor environments. Sources of outdoor particles are various
and include traffic and other combustion processes, and industrial and agricultural activities. Air
exchanges are driven by natural infiltration and ventilation, but also mechanical ventilation present in
the building.
All this can result in highly variable levels of indoor particles concentration that are not easily
ascertained or assessed in terms of their impacts on health.
Epidemiological studies have shown that ultrafine particles (UFP) can have a negative impact on
[1]
peoples' health. Due to their very small size they can indeed penetrate deeply into the human body.
Particle measurement instrumentation allows determining either the total particle number
concentration or the particle number size distribution. This document describes the general strategies
for the measurement of indoor sub-micron particles with the focus on determining the total number
concentration.
This document was prepared in response to the need for improved comparability of methods for
particle measurement.
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INTERNATIONAL STANDARD ISO 16000-42:2023(E)
Indoor air —
Part 42:
Measurement of the particle number concentration by
condensation particle counters
1 Scope
This document specifies the measurement methods and strategies for determining the total number
of airborne particles per unit volume of air indoor, using a condensation particle counter (CPC) for
particles approximately between 10 nm to 3 µm.
NOTE As the particle number concentration is usually dominated by the ultrafine particle (UFP) fraction,
the obtained result can be used as an approximation of the UFP concentration.
Quality assurance, determination of the measurement uncertainty and minimal reporting information
are also discussed in this document.
This document is applicable to indoor environments as specified in ISO 16000-1.
This document does not address the determination of bioaerosols or the chemical characterization
of particles. Nevertheless, some bioaerosols can be detected by the CPC and then contribute to the
measured count of particles.
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 16000-1, Indoor air — Part 1: General aspects of sampling strategy
ISO 16000-34, Indoor air — Part 34: Strategies for the measurement of airborne particles
ISO 27891, Aerosol particle number concentration — Calibration of condensation particle counters
CEN/TS 16976, Ambient air — Determination of the particle number concentration of atmospheric aerosol
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
aerosol
multi-phase system of solid and/or liquid particles (3.2) suspended in a gas, ranging in particle size
from 0,001 µm to 100 µm
[SOURCE: CEN/TS 16976:2016, 3.2]
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ISO 16000-42:2023(E)
3.2
particle
piece of matter with a defined physical boundary
Note 1 to entry: The phase of a particle can be solid, liquid or between solid and liquid, and a mixture of any of the
phases.
[SOURCE: ISO 27891:2015, 3.23]
3.3
fine particle
particle that is less than a few micrometers in diameter
3.4
ultrafine particle
UFP
particle (3.2) with a diameter of 100 nm or less
[SOURCE: ISO 16000-34:2018, 3.8]
3.5
particle number concentration
number of particles (3.2) related to the unit volume of indoor air
[SOURCE: ISO 27891:2015, 3.25, modified — Note 1 to entry and the symbol C have been deleted.]
3.6
detection efficiency
ratio of the concentration reported by an instrument to the actual concentration at the inlet of the
instrument
[SOURCE: ISO 27891:2015, 3.11, modified — the symbol η has been deleted.]
3.7
D
x
particle diameter for which a detection efficiency of the percentage of x is obtained when the CPC result
is compared to the reference concentration
Note 1 to entry: This detection efficiency is a function of the CPC itself, but depends also to some extent on
particle type.
Note 2 to entry: For the purpose of this document, silver particles and test conditions described in ISO 27891 are
considered.
3.8
nominal flow rate
volumetric flow rate indicated on the instrument specification sheet by the manufacturer
Note 1 to entry: The nominal flow rate is that flow rate, which a specific CPC model is designed for by the
manufacturer. The real flow rate of individual instruments can differ from the nominal flow due to manufacturing
tolerances.
[SOURCE: CEN/TS 16976:2016, 3.7]
3.9
factory-certified flow rate
volumetric flow rate of an individual instrument at the time of factory calibration, measured at its inlet
under the actual air conditions, and documented on a check out certificate
[SOURCE: CEN/TS 16976:2016, 3.6]
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ISO 16000-42:2023(E)
3.10
actual flow rate
volumetric flow rate of an individual instrument, measured at its inlet under the actual air conditions
Note 1 to entry: It is recommended that the actual flow rate be measured in regular intervals during operation.
[SOURCE: CEN/TS 16976:2016, 3.1]
3.11
calculation flow rate
flow rate which directly relates count rate and particle number concentration
Note 1 to entry: This flow rate is used for instrument internal calculation of the particle number concentration. It
depends on the instrument type and can be nominal, factory-certified or actual inlet flow rate. It can also include
a calibration factor unless the total inlet flow is analysed.
[SOURCE: CEN/TS 16976:2016, 3.3]
3.12
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards and corresponding
indications with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
[SOURCE: JCGM 200:2012, 2.39, modified — the notes have been deleted.]
3.13
uncertainty
parameter, associated with the result of a measurement, that characterizes the
dispersion of the values that can reasonably be attributed to the measurand
[SOURCE: JCGM 100:2008, 2.2.3, modified — the notes have been deleted.]
3.14
parallel measurement
measurement from a measuring system that takes samples from the same air over the same time period
[SOURCE: ISO 16000-37:2019, 3.13]
3.15
coincidence error
error that occurs with counting measuring methods when two or more particles are counted
simultaneously as a single particle
Note 1 to entry: Coincidence error is related to particle number concentration, flow velocity through the sensing
zone and the size of the sensing zone.
[SOURCE: CEN/TS 16976:2016, 3.4]
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
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ISO 16000-42:2023(E)
CPC condensation particle counter
DEG diethylene glycol
DEMC differential electrical mobility classifier
DMAS differential mobility aerosol spectrometer
MPSS mobility particle size spectrometer
QA quality assurance
QC quality control
SES size enhancer stage
SMPS scanning mobility particle sizer
SOA secondary organic aerosol
UFP ultrafine particle
5 Sources of airborne particles
5.1 General
Figure 1 shows the size range of airborne particles associated with different sources. These particles
can be generated by activities or without activities or be transported by air movement. These sources
[2],[3]
are different in their time of action and in the number and type of particles generated .
Figure 1 — Usual size range generated by usual indoor sources of airborne particles
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ISO 16000-42:2023(E)
Size range is different from one source to the other. Sources that can influence the indoor UFP
concentration are briefly listed below. Nevertheless, the total number is always clearly driven by the
smallest particles. Neglecting particles bigger than 1 µm will thus have an impact on total number
which is much lower than the total uncertainty of the method.
5.2 Combustion of organic material
[28]
Each combustion of organic material releases particles of different sizes, the majority of which are
particles in the size range <1 µm, primarily in the UFP range <0,1 µm. Research has shown that when
candles are burned, the level of UFP emissions depends on the candle material, but also the burn-up
5 3
process and that high particle number concentrations of more than 10 particles/cm can occur. Fine
and ultrafine particles can also be released into the room air during the operation of fireplaces and
stoves for example.
5.3 Smoking
Smoking is a significant anthropogenic and time-varying source of UFP indoors. Particle number
5 3
concentrations >10 particles/cm are easily produced, depending on the scenario under investigation.
[4],[5]
The use of electronic cigarettes (e-cigarettes) also leads to an increase in indoor air concentration
[6]
of UFPs and PM2,5 .
5.4 Cooking
Cooking activities of various kinds (e.g. baking, frying, deep-frying and toasting) can lead to very
5 3
high increases in ultrafine particle number concentrations (>10 particles/cm ). However, this can
vary greatly depending on the type of activity, energy input, food, ventilation conditions and room
[7],[8]
geometry .
5.5 Particle formation — Formation of secondary organic aerosol
Chemical reactions of the gas and aerosol phase can be responsible for the formation of new SOA
and for the modification of existing particles in indoor environments. SOA are formed mainly in the
presence of unsaturated compounds (e.g. monoterpenes) and ozone, nitrogen oxides and/or hydroxyl
[9]
radicals . User behaviour is also of great importance; for example, the use of chemical cleaning agents
[10]
can produce significant amount of SOA particles .
5.6 Outdoor air
UFPs also enter the interior from outside, in particular through infiltration and ventilation processes.
Typical external air sources are emissions from road traffic, combustion processes of all kinds and
industrial emissions. Photochemically induced secondary formation can also be a relevant source in the
outside air. During prolonged ventilation, the indoor and outdoor concentrations are usually equalized.
After ventilation, the concentration changes again due to prevailing sources, sinks and dynamics.
5.7 Other sources
The operation of office equipment with laser printing functions (printers, copiers, multifunction
devices) releases particles with diameters down to about 300 nm. Commercial and private 3D
printers (e.g. fused filament fabrication printers), which are becoming increasingly popular, process
plastic filaments into 3D objects in typical periods of up to several hours. Fine and ultrafine particles
are emitted into the environment. Devices in the lower and middle price categories are usually not
[11]
equipped with filters. UFP and fine particles of various types, quantities and size distributions are
also produced by processing spray paints and vanishes as well as by material processing, for example,
grinding, sawing or drilling during renovation work and do it yourself activities. Cleaning activities,
in particular vacuuming, can also lead to an increased release of UFP when using equipment without
effective filtration. Such emissions are situation specific and depend to a large extent on the materials,
products and equipment used as well as on the scope and frequency of the activity.
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ISO 16000-42:2023(E)
6 Dynamics of ultrafine particles indoors
6.1 General
In addition to the source emission of ultra-fine particles described in Clause 5, there are various dynamic
processes which can affect the measurement result (see Figure 2). Particle number concentrations and
particle size distributions indoors can indeed be subject to high spatial and temporal variability.
Responsible for this are:
— the number of possible emission sources, their spatial arrangement and time-dependent emission
patterns;
— the contribution of the particles penetrating from the outside and associated influencing factors,
such as environmental conditions (outdoor air quality, meteorology) and building conditions
(ventilation conditions, ventilation systems with and without filtering, construction, tightness
location of the object, floor);
— particle transport mechanisms (aerosol dilution, sedimentation, resuspension, thermophoresis and
diffusion);
— the laminar or turbulent air movement and air mixing in the room;
— temperature and humidity;
— conversion by chemical (oxidation) and physical processes (coagulation, evaporation, re-
condensation, gas-particle partitioning).
The processes depend on the concentration, size distribution and chemical composition of the emitted
[12]
primary particles. Compared to coarser particles, UFPs sometimes behave more like gas molecules;
they follow the air flow in the room and are distributed primarily by diffusion processes. In contrast
to coarser particles, sedimentation and resuspension are practically irrelevant for UFP. The speed and
extent of coagulation effects are strongly dependent on the initial concentration, size and width of the
size distribution of the primary particles. In spatially limited areas of very high number concentration
(downstream from a source), for example, coagulation of primary particles can occur much faster than
after homogeneous distribution of the particles over the entire spatial volume with a correspondingly
−3
smaller number concentration. At a concentration below approximately 10 000 cm , coagulation
[13]
effects in the ultrafine particle fraction typically occur only after a few hours .
These aspects should be considered when planning the measurement strategy and also when evaluating
the measurements, for example, by measuring and analysing the time response of an aerosol or different
aerosol size fractions over a longer period of time. In general, it should be considered that aerosol size
fractions can also be present outside the measuring range of the instruments used.
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ISO 16000-42:2023(E)
Key
1 exfiltration
2 phase transition
3 deposition
4 coagulation
5 formation
6 infiltration
Figure 2 — Dynamic processes influencing indoor particle pollution according to Reference [2]
6.2 Infiltration and exfiltration
Since a building envelope is never completely sealed, particles from the outside air always enter the
interior (infiltration equals
...
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