ISO 16000-37:2019

Indoor air - Part 37: Measurement of PM2,5 mass concentration

This document specifies the measurement methods and strategies for determining the PM2,5 mass concentrations of suspended particulate matter (PM) in indoor air. It can also be used for determining PM10 mass concentration. The reference method principle consists of collecting PM2,5 on a filter after separation of the particles by an impaction head and weighing them by means of a balance. Measurement procedure and main requirements are similar to the conditions specified in EN 12341. This document also specifies procedures for operating appropriate supplementary high time resolution instruments, which can be used to highlight peak emission, room investigation and as part of the quality control of the reference method. Quality assurance, determination of the measurement uncertainty and minimal reporting information are also part of this document. The lower range of application of this document is 2 µg/m3 of PM2,5 (i.e. the limit of detection of the standard measurement method expressed as its uncertainty). This document does not cover the determination of bioaerosols or the chemical characterization of particles. For the measurement and assessment of dust composition, see the relevant technical rules in the International Standards in the ISO 16000 series. This document does not cover passenger compartments of vehicles and public transport systems.

Air intérieur — Partie 37: Mesure de la concentration massique en PM2,5

Notranji zrak - 37. del: Določevanje masne koncentracije frakcije delcev PM2,5

Ta dokument določa merilne metode in strategije za določevanje masnih koncentracij PM2,5
suspendiranih trdnih delcev (PM) v notranjem zraku. Primeren je tudi za določevanje masne koncentracije PM10.
Načelo referenčne metode obsega zbiranje delcev PM2,5 na filtru, ki sledi ločevanju delcev z udarno glavo, in tehtanje delcev z uravnoteženjem.
Merilni postopek in glavne zahteve so podobni pogojem, določenim v standardu EN 12341.
Ta dokument tudi določa postopke za upravljanje ustreznih dodatnih inštrumentov z visoko časovno razločljivostjo, ki se lahko uporabljajo za označevanje največjih emisij, preiskave prostorov in kot del referenčne metode za nadzor kakovosti.
Ta dokument zajema tudi zagotavljanje kakovosti, ugotavljanje merilne negotovosti in minimalne informacije za poročanje.
Spodnje območje uporabe tega dokumenta je 2 μg/m3 za PM2,5 (npr. meja zaznavanja standardne merilne metode je izražena kot negotovost).
Ta dokument ne obravnava določevanja bioaerosolov ali kemijske karakterizacije
delcev. Za meritev in oceno sestave prahu glej ustrezna tehnična pravila v mednarodnih standardih iz skupine standardov ISO 16000.
Ta dokument ne obravnava potniških oddelkov v vozilih in sistemih javnega prevoza.

General Information

• Status: Published
• Publication Date: 30-Jan-2019
• ICS: 13.040.20 - Ambient atmospheres
• Technical Committee: ISO/TC 146/SC 6 - Indoor air
• Drafting Committee: ISO/TC 146/SC 6 - Indoor air
• Current Stage: 9093 - International Standard confirmed
• Start Date: 04-Jun-2024
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 16000-37:2019 - Indoor air - Part 37: Measurement of PM2,5 mass concentration

Relations

• Consolidated By: ISO 22301:2019 - Security and resilience - Business continuity management systems - Requirements
• Effective Date: 06-Jun-2022

Overview

ISO 16000-37:2019 - Indoor air - Measurement of PM2.5 mass concentration - specifies standardized methods and strategies for determining PM2.5 (and optionally PM10) mass concentrations in indoor environments. The standard defines a gravimetric reference method (collecting particles on a filter after separation by an impaction head and weighing) aligned with the conditions in EN 12341, plus procedures for supplementary high time resolution instruments, quality assurance, uncertainty estimation and minimal reporting requirements. The lower practical detection range is 2 µg/m3 (expressed as the method’s uncertainty). The document excludes bioaerosol analysis, particle chemical characterization and vehicle/passenger compartments.

Key topics and technical requirements

• Reference method (gravimetric):
  • Particle separation using an impaction head (size-selective inlet) followed by filter collection and precision weighing.
  • Measurement conditions similar to EN 12341; deviations must be specifically stated.
• Supplementary high time resolution methods:
  • Procedures for selecting and operating instruments that reveal short-term peaks, aid room investigations and support quality control of the reference method.
• Measurement strategy and sampling:
  • Typical sampling location: center of room at ~1.5 m height (see ISO 16000-1 / 16000-34).
  • Minimum one measurement per room; additional points if conditions vary.
  • Sampling volume per hour shall not exceed 10% of the room’s hourly exchanged air (or 10% of room volume if exchange unknown).
  • Noise and pump isolation considerations to avoid disturbing indoor occupants.
• Source attribution & operational states:
  • Guidance for classifying sources and testing under three states: resting without activity, resting with equipment active, active user state.
• Quality assurance and reporting:
  • Requirements for QA/QC, calibration, flow and weighing system checks, and uncertainty evaluation.
  • Minimal reporting information and recommendations for parallel outdoor measurements to contextualize indoor PM levels.
• Scope limits: does not cover bioaerosols, chemical composition analysis, or vehicle passenger compartments.

Applications and users

ISO 16000-37 is intended for:

• Indoor air quality (IAQ) professionals and consultants performing PM2.5 assessments
• Accredited testing laboratories conducting gravimetric PM measurements
• Building scientists, HVAC engineers and facility managers evaluating ventilation and emission sources
• Public health researchers and policymakers comparing indoor particulate exposures
• Regulatory bodies and auditors requiring traceable, comparable PM2.5 measurement results indoors

Practical uses include source identification (cooking, smoking, wood burning), peak-emission characterization, compliance testing using the reference method, and QA/QC of continuous monitors.

Related standards

• EN 12341 (ambient air gravimetric PM measurement) - referenced for procedural conditions
• Other parts of the ISO 16000 series (e.g., ISO 16000-1, ISO 16000-34) for location, sampling strategy and complementary indoor air protocols

For implementation, obtain the full ISO 16000-37:2019 text from ISO or your national standards body to ensure compliance with all procedural and reporting details.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2019
Notranji zrak - 37. del: Določevanje masne koncentracije frakcije delcev PM2,5
Indoor air - Part 37: Measurement of PM2,5 mass concentration
Air intérieur - Partie 37: Mesure de la concentration massique en PM2,5
Ta slovenski standard je istoveten z: ISO 16000-37:2019
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 16000-37
First edition
2019-02
Indoor air —
Part 37:
Measurement of PM mass
2,5
concentration
Air intérieur —
Partie 37: Mesure de la concentration massique en PM
2,5
Reference number
©
ISO 2019
© ISO 2019
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Measurement strategy for determing PM indoors . 3
2,5
5.1 Location and number of sampling points . 3
5.2 Measurement strategy for source attribution . 4
5.3 Indoor air condition . 4
6 Principle of measurement . 4
6.1 General considerations . 4
6.2 Description of the standard measuring principle . 4
7 Equipment and facilities. 5
7.1 Sampling system components . 5
7.2 Weighing facilities and procedure . 5
8 Supplementary high time resolution method . 5
8.1 General . 5
8.2 Selection of the supplementary instrument . 6
8.3 Supplementary procedure . 6
9 Evaluation and reporting the results . 6
10 Quality assurance and uncertainty evaluation . 7
10.1 Reference method . 7
10.1.1 General. 7
10.1.2 Flow control system . 7
10.1.3 Weighing system . 7
10.1.4 Checking the equipment’s parameters . 7
10.2 Supplementary methods . 8
Annex A (informative) Examples of particle concentrations encountered during room user
activities . 9
Bibliography .11
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 6,
Indoor air.
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.
A list of all parts in the ISO 16000 series can be found on the ISO website.
iv © ISO 2019 – All rights reserved

Introduction
Airborne particulate matter (colloquially known as “fine dust”) plays a role not only outdoors, but is
also significant in terms of hygiene, especially indoors. People in industrialized countries spend most
of the day indoors. Either particles are transported into indoor air from outdoor environments or the
particles directly result from indoor sources, such as smoking, residential wood burning and cooking.
PM concentration and composition in indoor environments strongly depend on parameters such as
2,5
the room size, relative humidity, air exchange rate, airflow conditions and sink effects on surfaces (e.g.
walls, ceilings, floor coverings, furnishings). In addition, particles already sedimented are temporarily
resuspended to the air through various activities and can be inhaled. All this can result in highly
variable levels of indoor PM pollution that are not easily ascertained or assessed in terms of their
2,5
impacts on health.
This document describes the general strategies for the measurement of indoor PM concentration.
2,5
This document was prepared in response to the need for improved comparability of methods for
particle measurement.
INTERNATIONAL STANDARD ISO 16000-37:2019(E)
Indoor air —
Part 37:
Measurement of PM mass concentration
2,5
1 Scope
This document specifies the measurement methods and strategies for determining the PM mass
2,5
concentrations of suspended particulate matter (PM) in indoor air. It can also be used for determining
PM mass concentration.
The reference method principle consists of collecting PM on a filter after separation of the particles
2,5
by an impaction head and weighing them by means of a balance.
Measurement procedure and main requirements are similar to the conditions specified in EN 12341.
This document also specifies procedures for operating appropriate supplementary high time resolution
instruments, which can be used to highlight peak emission, room investigation and as part of the
quality control of the reference method.
Quality assurance, determination of the measurement uncertainty and minimal reporting information
are also part of this document.
The lower range of application of this document is 2 µg/m of PM (i.e. the limit of detection of the
2,5
standard measurement method expressed as its uncertainty).
This document does not cover the determination of bioaerosols or the chemical characterization of
particles. For the measurement and assessment of dust composition, see the relevant technical rules in
the International Standards in the ISO 16000 series.
This document does not cover passenger compartments of vehicles and public transport systems.
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.
EN 12341, Ambient air — Standard gravimetric measurement method for the determination of the PM or
PM mass concentration of suspensed particulate matter
2,5
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological 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
aerodynamic diameter
−3
diameter of a sphere of density 1 g cm and the same setting velocity in still air as the particle of
interest under prevailing conditions of temperature, pressure and relative humidity
Note 1 to entry: The aerodynamic diameter is calculated using the formula:

p
DD
ap
 
where
D is the aerodynamic diameter;
a
D is the particle diameter;
p
ρ is the density of the particle;
p
ρ is the standard density;
χ is the form factor.
Note 2 to entry: The form factor describes by how much the resisting force of an irregular shaped particle is
[10]
greater than that of a sphere with the same volume .
Note 3 to entry: The aerodynamic diameter determines the sedimentation and the separation properties of
particles in impactors. It is also of particular importance for penetrative behaviour and the retention of particles
in the human body.
Note 4 to entry: Various definitions are used for the particle diameter, depending on the measurement method.
These different diameters are only indirectly comparable since different particle properties are being measured,
e.g. geometric diameter, diameter according to dielectric mobility, diameter according to light scattering
properties.
[SOURCE: ISO 7708:1995, 2.2, modified — “particle” has been removed from the term, the definition has
been reworded, and the original Note 1 to entry has been replaced by Notes 1 to 4 to entry.]
3.3
mass concentration
c
ratio of the mass m of the measured component and the gas volume V, as shown by:
m
c=
V
[SOURCE: EN 15259:2007, 3.26]
3.4
particle
small discrete mass or solid or liquid matter
[SOURCE: ISO 29464:2017, 3.2.111]
3.5
PM
x
particulate matter suspended in air which is small enough to pass through a size-selective inlet with a
50 % efficiency cut-off at x µm aerodynamic diameter
[SOURCE: EN 12341:2014, 3.1.14]
2 © ISO 2019 – All rights reserved

3.6
cut-off diameter
aerodynamic diameter at which the impactor stage has a separation efficiency of 50 %
[SOURCE: ISO 23210:2009, 3.1.2, modified — The definition has been changed from “where the
separation efficiency of the impactor stage is 50 %”.]
3.7
calibration
operation which, 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 removed.]
3.8
uncertainty
parameter, associated with the result of a measurement, that characterizes the
dispersion of the values that could reasonably be attributed to the measurand
[SOURCE: JCGM 100:2008, 2.2.3, modified — The notes have been removed.]
3.13
parallel measurement
measurement from a measuring system that takes samples from the same air over the same time period
3.14
reference method
RM
measurement method(ology) which, by convention, gives the accepted reference value of the
measurement
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
JCGM Joint Committee for Guides in Metrology
PM particulate matter
QA quality assurance
QC quality control
5 Measurement strategy for determing PM indoors
2,5
5.1 Location and number of sampling points
The measurement usually takes place in the centre of the room at approximately 1,5 m height (see
ISO 16000-1 and ISO 16000-34).
As a minimum, one measurement per investigated room should be performed. If stable conditions
cannot be guaranteed for all points in the same room, additional locations should be investigated.
The sampling volume extracted per hour shall not exceed 10 % of the hourly volume of room air
exchanged. If this is unknown, the sampling volume extracted per hour shall not exceed 10 % of the
room’s volume.
The indoor area is usually a quieter space compared to outdoors. Additional isolation of the sampling
system or relocating the pump outside the room should be considered to limit noise impact.
5.2 Measurement strategy for source attribution
The indoor sources of PM are diverse. ISO 16000-34 describes the necessary procedure for assigning
and evaluating individual indoor sources. The number and place of the sampling points are also
specified in this document, taking into account the type of room and expected activity.
In order to classify the relevance of specific sources, indoor measurements under different conditions
(examples are given in Annex A) may be necessary. Furthermore, three different operational states are
defined.
a) Resting state without activity: This state is characterized by the absence of users and user activities
and by switching off all fixed equipment (e.g. ventilation system, gas heating, refrigerators, servers).
b) Resting state with equipment activity: This state is characterized the absence of users and user
activities, but with operation of all fixed and/or constantly operated equipment.
c) Active user state: This state is characterized by usage activity of the relevant persons and by the
operation of all fixed and/or constantly operated equipment.
5.3 Indoor air condition
Indoor air conditions (e.g. temperature, pressure, humidity) have a direct effect on indoor air
measurements. These parameters shall be measured in the investigated room and specified in the report.
Outdoor conditions (e.g. rain, strong wind) can strongly affect the result. Thus, parallel outdoor
measurements of PM are always recommended.
2,5
The user’s normal ventilation arrangements should be maintained. The usage and ventilation conditions
can be documented through concurrent measurements of CO concentration.
The impact of door and window openings can be very important. This aspect should be discussed with
the client and the situation during the measurement should be documented in the report.
6 Principle of measurement
6.1 General considerations
For source regulatory purposes (i.e. for comparison with an assessment value, for auditing whether it is
complied with), only the reference method described in Clauses 6 and 7 can be used.
6.2 Description of the standard measuring principle
The conditions for determining the PM particle mass concentration shall conform to the conditions
2,5
specified in EN 12341. A specific statement shall be given when deviatio
...

INTERNATIONAL ISO
STANDARD 16000-37
First edition
2019-02
Indoor air —
Part 37:
Measurement of PM mass
2,5
concentration
Air intérieur —
Partie 37: Mesure de la concentration massique en PM
2,5
Reference number
©
ISO 2019
© ISO 2019
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Measurement strategy for determing PM indoors . 3
2,5
5.1 Location and number of sampling points . 3
5.2 Measurement strategy for source attribution . 4
5.3 Indoor air condition . 4
6 Principle of measurement . 4
6.1 General considerations . 4
6.2 Description of the standard measuring principle . 4
7 Equipment and facilities. 5
7.1 Sampling system components . 5
7.2 Weighing facilities and procedure . 5
8 Supplementary high time resolution method . 5
8.1 General . 5
8.2 Selection of the supplementary instrument . 6
8.3 Supplementary procedure . 6
9 Evaluation and reporting the results . 6
10 Quality assurance and uncertainty evaluation . 7
10.1 Reference method . 7
10.1.1 General. 7
10.1.2 Flow control system . 7
10.1.3 Weighing system . 7
10.1.4 Checking the equipment’s parameters . 7
10.2 Supplementary methods . 8
Annex A (informative) Examples of particle concentrations encountered during room user
activities . 9
Bibliography .11
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 6,
Indoor air.
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.
A list of all parts in the ISO 16000 series can be found on the ISO website.
iv © ISO 2019 – All rights reserved

Introduction
Airborne particulate matter (colloquially known as “fine dust”) plays a role not only outdoors, but is
also significant in terms of hygiene, especially indoors. People in industrialized countries spend most
of the day indoors. Either particles are transported into indoor air from outdoor environments or the
particles directly result from indoor sources, such as smoking, residential wood burning and cooking.
PM concentration and composition in indoor environments strongly depend on parameters such as
2,5
the room size, relative humidity, air exchange rate, airflow conditions and sink effects on surfaces (e.g.
walls, ceilings, floor coverings, furnishings). In addition, particles already sedimented are temporarily
resuspended to the air through various activities and can be inhaled. All this can result in highly
variable levels of indoor PM pollution that are not easily ascertained or assessed in terms of their
2,5
impacts on health.
This document describes the general strategies for the measurement of indoor PM concentration.
2,5
This document was prepared in response to the need for improved comparability of methods for
particle measurement.
INTERNATIONAL STANDARD ISO 16000-37:2019(E)
Indoor air —
Part 37:
Measurement of PM mass concentration
2,5
1 Scope
This document specifies the measurement methods and strategies for determining the PM mass
2,5
concentrations of suspended particulate matter (PM) in indoor air. It can also be used for determining
PM mass concentration.
The reference method principle consists of collecting PM on a filter after separation of the particles
2,5
by an impaction head and weighing them by means of a balance.
Measurement procedure and main requirements are similar to the conditions specified in EN 12341.
This document also specifies procedures for operating appropriate supplementary high time resolution
instruments, which can be used to highlight peak emission, room investigation and as part of the
quality control of the reference method.
Quality assurance, determination of the measurement uncertainty and minimal reporting information
are also part of this document.
The lower range of application of this document is 2 µg/m of PM (i.e. the limit of detection of the
2,5
standard measurement method expressed as its uncertainty).
This document does not cover the determination of bioaerosols or the chemical characterization of
particles. For the measurement and assessment of dust composition, see the relevant technical rules in
the International Standards in the ISO 16000 series.
This document does not cover passenger compartments of vehicles and public transport systems.
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.
EN 12341, Ambient air — Standard gravimetric measurement method for the determination of the PM or
PM mass concentration of suspensed particulate matter
2,5
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological 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
aerodynamic diameter
−3
diameter of a sphere of density 1 g cm and the same setting velocity in still air as the particle of
interest under prevailing conditions of temperature, pressure and relative humidity
Note 1 to entry: The aerodynamic diameter is calculated using the formula:

p
DD
ap
 
where
D is the aerodynamic diameter;
a
D is the particle diameter;
p
ρ is the density of the particle;
p
ρ is the standard density;
χ is the form factor.
Note 2 to entry: The form factor describes by how much the resisting force of an irregular shaped particle is
[10]
greater than that of a sphere with the same volume .
Note 3 to entry: The aerodynamic diameter determines the sedimentation and the separation properties of
particles in impactors. It is also of particular importance for penetrative behaviour and the retention of particles
in the human body.
Note 4 to entry: Various definitions are used for the particle diameter, depending on the measurement method.
These different diameters are only indirectly comparable since different particle properties are being measured,
e.g. geometric diameter, diameter according to dielectric mobility, diameter according to light scattering
properties.
[SOURCE: ISO 7708:1995, 2.2, modified — “particle” has been removed from the term, the definition has
been reworded, and the original Note 1 to entry has been replaced by Notes 1 to 4 to entry.]
3.3
mass concentration
c
ratio of the mass m of the measured component and the gas volume V, as shown by:
m
c=
V
[SOURCE: EN 15259:2007, 3.26]
3.4
particle
small discrete mass or solid or liquid matter
[SOURCE: ISO 29464:2017, 3.2.111]
3.5
PM
x
particulate matter suspended in air which is small enough to pass through a size-selective inlet with a
50 % efficiency cut-off at x µm aerodynamic diameter
[SOURCE: EN 12341:2014, 3.1.14]
2 © ISO 2019 – All rights reserved

3.6
cut-off diameter
aerodynamic diameter at which the impactor stage has a separation efficiency of 50 %
[SOURCE: ISO 23210:2009, 3.1.2, modified — The definition has been changed from “where the
separation efficiency of the impactor stage is 50 %”.]
3.7
calibration
operation which, 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 removed.]
3.8
uncertainty
parameter, associated with the result of a measurement, that characterizes the
dispersion of the values that could reasonably be attributed to the measurand
[SOURCE: JCGM 100:2008, 2.2.3, modified — The notes have been removed.]
3.13
parallel measurement
measurement from a measuring system that takes samples from the same air over the same time period
3.14
reference method
RM
measurement method(ology) which, by convention, gives the accepted reference value of the
measurement
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
JCGM Joint Committee for Guides in Metrology
PM particulate matter
QA quality assurance
QC quality control
5 Measurement strategy for determing PM indoors
2,5
5.1 Location and number of sampling points
The measurement usually takes place in the centre of the room at approximately 1,5 m height (see
ISO 16000-1 and ISO 16000-34).
As a minimum, one measurement per investigated room should be performed. If stable conditions
cannot be guaranteed for all points in the same room, additional locations should be investigated.
The sampling volume extracted per hour shall not exceed 10 % of the hourly volume of room air
exchanged. If this is unknown, the sampling volume extracted per hour shall not exceed 10 % of the
room’s volume.
The indoor area is usually a quieter space compared to outdoors. Additional isolation of the sampling
system or relocating the pump outside the room should be considered to limit noise impact.
5.2 Measurement strategy for source attribution
The indoor sources of PM are diverse. ISO 16000-34 describes the necessary procedure for assigning
and evaluating individual indoor sources. The number and place of the sampling points are also
specified in this document, taking into account the type of room and expected activity.
In order to classify the relevance of specific sources, indoor measurements under different conditions
(examples are given in Annex A) may be necessary. Furthermore, three different operational states are
defined.
a) Resting state without activity: This state is characterized by the absence of users and user activities
and by switching off all fixed equipment (e.g. ventilation system, gas heating, refrigerators, servers).
b) Resting state with equipment activity: This state is characterized the absence of users and user
activities, but with operation of all fixed and/or constantly operated equipment.
c) Active user state: This state is characterized by usage activity of the relevant persons and by the
operation of all fixed and/or constantly operated equipment.
5.3 Indoor air condition
Indoor air conditions (e.g. temperature, pressure, humidity) have a direct effect on indoor air
measurements. These parameters shall be measured in the investigated room and specified in the report.
Outdoor conditions (e.g. rain, strong wind) can strongly affect the result. Thus, parallel outdoor
measurements of PM are always recommended.
2,5
The user’s normal ventilation arrangements should be maintained. The usage and ventilation conditions
can be documented through concurrent measurements of CO concentration.
The impact of door and window openings can be very important. This aspect should be discussed with
the client and the situation during the measurement should be documented in the report.
6 Principle of measurement
6.1 General considerations
For source regulatory purposes (i.e. for comparison with an assessment value, for auditing whether it is
complied with), only the reference method described in Clauses 6 and 7 can be used.
6.2 Description of the standard measuring principle
The conditions for determining the PM particle mass concentration shall conform to the conditions
2,5
specified in EN 12341. A specific statement shall be given when deviation from EN 12341 is allowed or
mandatory.
Indoor air is passed through a size-selective inlet at a known, constant flow rate. Due to their inertia,
large particles are collected on a greased impactor plate. Small particles follow the gas stream and
are collected on a backup filter. The sampling head is constructed in such a way that only the particle
size fraction with diameters up to the specified cut-off value of 2,5 µm is deposited on the filter. The
P
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