CEN ISO/TS 12025:2021

Nanomaterials - Quantification of nano-object release from powders by generation of aerosols (ISO/TS 12025:2021)

This document describes methods for the quantification of nano-object release from powders as a result of treatment, ranging from handling to high energy dispersion, by measuring aerosols liberated after a defined aerosolization procedure. Particle number concentration and size distribution of the aerosol are measured and the mass concentration is derived. This document provides information on factors to be considered when selecting among the available methods for powder sampling and treatment procedures and specifies minimum requirements for test sample preparation, test protocol development, measuring particle release and reporting data. In order to characterize the full size range of particles generated, the measurement of nano-objects as well as agglomerates and aggregates is adressed in this document.
This document does not include the characterization of particle sizes within the powder. Tribological methods are excluded where direct mechanical friction is applied to grind or abrade the material.

Nanomaterialien - Quantifizierung der Freisetzung von Nanoobjekten aus Pulvern durch Aerosolerzeugung (ISO/TS 12025:2021)

Dieses Dokument beschreibt Verfahren zur Quantifizierung der Nanoobjekt-Freisetzung aus Pulvern als Ergebnis des gesamten Verfahrens, vom Handling bis zu hoch-energetischer Dispergierung, durch Messung des entstehenden Aerosols nach definierter Pulverbeanspruchung. Partikelanzahlkonzentration und  größenverteilung des Aerosols werden gemessen und die Massenkonzentration abgeleitet. Dieses Dokument liefert Angaben über zu beachtende Faktoren bei der Auswahl unter den zur Verfügung stehenden Verfahren zur Probennahme und Behandlung von Pulvern und legt Mindestanforderungen an die Probenherstellung, die Erarbeitung des Prüfprotokolls, die Messung der Partikelfreisetzung und die anzugebenden Daten fest. Damit der vollständige Größenbereich der erzeugten Partikel charakterisiert werden kann, wird in diesem Dokument neben der Messung von Nanoobjekten auch die Messung von Agglomeraten und Aggregaten behandelt.
Dieses Dokument behandelt nicht die Charakterisierung von Partikelgrößen innerhalb des Pulvers. Tribologische Verfahren, bei denen das Material mittels direkter mechanischer Reibung bearbeitet wird, um es abzureiben oder zu schleifen, sind ausgeschlossen.

Nanomatériaux - Quantification de la libération de nano-objets par les poudres par production d'aérosols (ISO/TS 12025:2021)

Le présent document décrit des méthodes pour la quantification de la libération de nano-objets par les poudres en conséquence d’un traitement, allant de la manipulation à une dispersion à haute énergie, par mesurage des aérosols libérés après un mode opératoire défini d’aérosolisation. La concentration en nombre de particules et la distribution granulométrique de l’aérosol sont mesurées et la concentration massique est calculée. Le présent document fournit des informations sur les facteurs à prendre en compte pour la sélection des méthodes pour l’échantillonnage des poudres et les modes opératoires de traitement. Il spécifie également les exigences minimales pour la préparation des échantillons d’essai, le développement du protocole d’essai, le mesurage de la libération de particules et la consignation des données. Afin de caractériser toute la plage granulométrique des particules générées, le mesurage des nano-objets ainsi que des agglomérats et des agrégats est addressé dans le présent document.
Le présent document n’inclut pas la caractérisation granulométrique des particules au sein de la poudre. Les méthodes tribologiques sont exclues lorsqu’un frottement mécanique direct est appliqué pour broyer ou éroder le matériau.

Nanomateriali - Kvantifikacija sproščanja nanoobjektov iz prahu s proizvodnjo aerosola (ISO/TS 12025:2021)

General Information

• Status: Published
• Publication Date: 01-Jun-2021
• ICS: 07.120 - Nanotechnologies
• Technical Committee: CEN/TC 352 - Nanotechnologies
• Drafting Committee: CEN/TC 352 - Nanotechnologies
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 02-Jun-2021
• Completion Date: 02-Jun-2021
• Ref Project: SIST-TS CEN ISO/TS 12025:2021 - Nanomaterials - Quantification of nano-object release from powders by generation of aerosols (ISO/TS 12025:2021)

Relations

• Replaces: CEN ISO/TS 12025:2015 - Nanomaterials - Quantification of nano-object release from powders by generation of aerosols (ISO/TS 12025:2012)
• Effective Date: 23-Jan-2017

Overview

CEN ISO/TS 12025:2021 - "Nanomaterials - Quantification of nano-object release from powders by generation of aerosols" - is a Technical Specification from ISO/CEN that defines methods to quantify the release of nano-objects from powder materials by generating and measuring aerosols. The standard covers the full measurement chain - generation, transport and measurement - and specifies minimum requirements for sample preparation, test protocol development, measurement of particle release, and reporting. Measured outputs include particle number concentration, particle size distribution, and derived mass concentration for nano-objects as well as their agglomerates and aggregates.

Key topics and requirements

• Scope and exclusions
  • Applies to release of nano-objects from powders via aerosolization (handling → high-energy dispersion).
  • Does not cover particle size characterization within the bulk powder.
  • Tribological methods (direct mechanical grinding/abrasion) are excluded.
• Measurement stages
  • Three core stages: generation (aerosolization), transport (minimizing losses and agglomeration), and measurement (instrument sampling).
• Test design and minimum requirements
  • Guidance on selecting powder sampling and sample treatment procedures (dustiness generation and dispersing methods).
  • Sample preparation, safety assessment, and documentation requirements.
  • Selection criteria for measuring methods according to generation system characteristics (time-dependence, transport losses).
• Measurement outputs
  • Particle number concentration and size distribution across the nanoscale and larger agglomerates/aggregates; mass concentration derived from number and size data.
• Protocol and reporting
  • Minimum criteria for test setups, protocol reproducibility, and comprehensive test reports describing methods, parameters, and results.
• Annexes provide informative guidance (e.g., dynamic methods, dispersing methods, choosing measuring instruments).

Applications and users

• Practical for:
  • Nanomaterial manufacturers and formulators assessing potential release during handling and processing.
  • Occupational hygiene and safety teams developing exposure mitigation strategies.
  • Research laboratories validating dispersion and aerosolization behavior of powders.
  • Test houses creating standardized protocols for comparative testing.
• Use cases:
  • Comparing nano-object release between different powder formulations.
  • Evaluating process changes (handling, milling, packaging) that influence aerosol release.
  • Supporting safer-by-design decisions and engineering controls (though the standard is not a health risk assessment or a replacement for dustiness testing).

Related standards

• ISO/TS 80004-1:2015 - Nanotechnologies - Vocabulary (core terms)
• ISO/TS 80004-2:2015 - Nanotechnologies - Vocabulary (nano-objects)
• Refer to the standard’s informative annexes and bibliography for additional methodological guidance and linked test methods.

Keywords: nanomaterials, nano-object release, aerosols, powders, aerosolization, particle number concentration, size distribution, dustiness, dispersion, agglomerates, test protocols.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2021
Nadomešča:
SIST-TS CEN ISO/TS 12025:2015
Nanomateriali - Kvantifikacija sproščanja nanoobjektov iz prahu s proizvodnjo
aerosola (ISO/TS 12025:2021)
Nanomaterials - Quantification of nano-object release from powders by generation of
aerosols (ISO/TS 12025:2021)
Nanomaterialien - Quantifizierung der Freisetzung von Nanoobjekten aus Pulvern durch
Aerosolerzeugung (ISO/TS 12025:2021)
Nanomatériaux - Quantification de la libération de nano-objets par les poudres par
production d'aérosols (ISO/TS 12025:2021)
Ta slovenski standard je istoveten z: CEN ISO/TS 12025:2021
ICS:
07.120 Nanotehnologije Nanotechnologies
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN ISO/TS 12025
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
June 2021
TECHNISCHE SPEZIFIKATION
ICS 07.120 Supersedes CEN ISO/TS 12025:2015
English Version
Nanomaterials - Quantification of nano-object release from
powders by generation of aerosols (ISO/TS 12025:2021)
Nanomatériaux - Quantification de la libération de Nanomaterialien - Quantifizierung der Freisetzung von
nano-objets par les poudres par production d'aérosols Nanoobjekten aus Pulvern durch Aerosolerzeugung
(ISO/TS 12025:2021) (ISO/TS 12025:2021)
This Technical Specification (CEN/TS) was approved by CEN on 29 January 2021 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 12025:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (CEN ISO/TS 12025:2021) has been prepared by Technical Committee ISO/TC 229
"Nanotechnologies" in collaboration with Technical Committee CEN/TC 352 “Nanotechnologies” the
secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes CEN ISO/TS 12025:2015.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO/TS 12025:2021 has been approved by CEN as CEN ISO/TS 12025:2021 without any
modification.
TECHNICAL ISO/TS
SPECIFICATION 12025
Second edition
2021-05
Nanomaterials — Quantification of
nano-object release from powders by
generation of aerosols
Nanomatériaux — Quantification de la libération de nano-objets par
les poudres par production d'aérosols
Reference number
ISO/TS 12025:2021(E)
©
ISO 2021
ISO/TS 12025:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
Contents Page
Foreword .iv
Introduction .v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
3.1 General terms . 1
3.2 Terms related to particle properties and measurement . 2
4  Symbols . 5
5  Factors influencing results of nano-object release from powders .5
5.1 Test generation method selection . 5
5.2 Material properties influencing nano-object release from powder . 5
5.3 Test stages . 6
6 Test requirements . 7
6.1 General . 7
6.2 Safety assessment . 7
6.3 Sample preparation . 8
6.4 Sample treatment . 8
6.4.1 Dustiness generation methods . 8
6.4.2 Dispersing methods for aerosol generation . 9
6.4.3 Sample treatment execution and report . 9
6.5 Measurement of aerosolized nano-objects .10
6.5.1 Selection of the measuring method .10
6.5.2 Transport and sampling parameters .11
6.5.3 Considerations before testing .12
6.5.4 Size and concentration measurement results .12
6.5.5 Particle size distribution and other characteristic measurement parameters .14
7  Requirements for test setups and protocols .15
8  Test report .16
Annex A (informative) Considerations for the selection of the sample treatment procedure .17
Annex B (informative) Dustiness reference test methods .19
Annex C (informative) Dynamic method .22
Annex D (informative) Dispersing methods .26
Annex E (informative) Selection of the nano-object measuring method .27
Annex F (informative) Dry dispersion intensity in measuring devices .29
Bibliography .30
ISO/TS 12025:2021(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 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 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 229, Nanotechnologies, in collaboration
with the European Committee for Standardization (CEN) Technical Committee CEN/TC 352,
Nanotechnologies, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This second edition cancels and replaces the first edition (ISO/TS 12025:2012), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— revised and updated the Introduction and the Bibliography;
— updated 6.4.1 and 6.4.2 and Annex A with regards to the description and selection of the sample
treatment procedure in accordance with new European standards.
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 © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
Introduction
Industrial powders when subjected to external energy or stress from handling and air flow will release
particles entrained in the surrounding air to form aerosols. Aerosols in the nanoscale are more dynamic
than micrometre sized particles because of greater sensitivity to physical effects such as Brownian
diffusion. Porosity and cohesion of the powder can be much higher than for materials containing
larger particles with more resistance to flow and lower volume-specific surface area. Nano-objects in
powdered nanostructured materials can dominate relevant properties of the bulk material by particle-
particle interactions that form clusters such as agglomerates.
Aerosol release characterization consists of three main stages: generation, transport and measurement.
In general, to reduce transport losses and aerosol agglomeration, the distance between generation and
[35]
measurement should be minimized. Although there are potentially many different approaches ,
the generation of an aerosol is usually physically modelled on different representative scenarios (e.g.
to simulate typical manual or machine powder handling processes or worst-case highly energetic
dispersion).
This document is only applicable for measuring the release of nano-objects from powders. This
allows comparisons of the nano-object release from different powders using the same generation and
measurement system. The choice of the measurement method must take into account the characteristics
(e.g. time-related dependence) of the generation system and the potential for losses and agglomeration
during the transport and entry into the measuring instrumentation. Therefore, this document provides
a summary of the generation and measurement methods currently available to assist material scientists
and engineers in comparing the nano-object release from different powders.
The quantification of the release of nano-objects from powders described in this document cannot be
used as a substitute for dustiness testing or for a health-related risk assessment.
TECHNICAL SPECIFICATION ISO/TS 12025:2021(E)
Nanomaterials — Quantification of nano-object release
from powders by generation of aerosols
WARNING — The execution of the provisions of this document should be entrusted only to
appropriately qualified and experienced people, for whose use it has been produced.
1  Scope
This document describes methods for the quantification of nano-object release from powders as a
result of treatment, ranging from handling to high energy dispersion, by measuring aerosols liberated
after a defined aerosolization procedure. Particle number concentration and size distribution of the
aerosol are measured and the mass concentration is derived. This document provides information
on factors to be considered when selecting among the available methods for powder sampling and
treatment procedures and specifies minimum requirements for test sample preparation, test protocol
development, measuring particle release and reporting data. In order to characterize the full size range
of particles generated, the measurement of nano-objects as well as agglomerates and aggregates is
adressed in this document.
This document does not include the characterization of particle sizes within the powder. Tribological
methods are excluded where direct mechanical friction is applied to grind or abrade the material.
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/TS 80004-1:2015, Nanotechnologies — Vocabulary — Part 1: Core terms
ISO/TS 80004-2:2015, Nanotechnologies — Vocabulary — Part 2: Nano-objects
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TS 80004-1:2015,
ISO/TS 80004-2:2015 and the following 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 http:// www .electropedia .org/
3.1  General terms
3.1.1
release from powder
transfer of material from a powder to a liquid or gas as a consequence of a disturbance
3.1.2
nano-object number release
n
total number of nano-objects (3.2.9), released from a sample as a consequence of a disturbance
ISO/TS 12025:2021(E)
3.1.3
nano-object release rate
n
t
total number of nano-objects (3.2.9), released per second as a consequence of a disturbance
3.1.4
mass specific nano-object number release
n
m
nano-object number release (3.1.2), divided by the mass of the sample before a disturbance
3.1.5
mass loss specific nano-object number release
n
∆m
nano-object number release (3.1.2), divided by the mass difference of the sample before and after a
disturbance
3.1.6
nano-object aerosol number concentration
c
n
number of nano-objects (3.2.9) per aerosol volume unit in the sample treatment zone
3.1.7
aerosol volume flow rate
V
t
volume flow rate through the sample treatment zone
3.2  Terms related to particle properties and measurement
3.2.1
aerosol
system of solid or liquid particles suspended in gas
[SOURCE: ISO 15900:2009, 2.1]
3.2.2
equivalent spherical diameter
diameter of a sphere having the same physical properties as the particle in the measurement
Note 1 to entry: Physical properties are, for instance, the same settling velocity or electrolyte solution displacing
volume or projection area under a microscope.
Note 2 to entry: The physical property to which the equivalent diameter refers shall be indicated using a suitable
subscript, e.g. x for equivalent surface area diameter or x for equivalent volume diameter.
s v
[SOURCE: ISO/TS 80004-2:2015, A.2.3]
3.2.3
particle size distribution
PSD
cumulative distribution or distribution density of a quantity of particle sizes, represented by equivalent
spherical diameters (3.2.2) or other linear dimensions
[3]
Note 1 to entry: Quantity measures and types of distributions are defined in ISO 9276-1:1998 .
3.2.4
PM
2,5
particulate matter smaller than 2,5 µm
mass concentration of fine particulate matter having an aerodynamic diameter less than or equal to a
nominal 2,5 micrometres
Note 1 to entry: See Appendix J in Reference [47].
2 © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
3.2.5
PM
particulate matter smaller than 10 µm
mass concentration of fine particulate matter having an aerodynamic diameter less than or equal to a
nominal 10 micrometres
Note 1 to entry: See Appendix J in Reference [47].
[15]
Note 2 to entry: PM is used for the thoracic fraction as explained in EN 481:1993 .
3.2.6
condensation particle counter
CPC
instrument that measures the particle number concentration of an aerosol (3.2.1) using a condensation
effect to increase the size of the aerosolized particles
Note 1 to entry: The sizes of particles detected are usually smaller than several hundred nanometres and larger
than a few nanometres.
Note 2 to entry: A CPC is one possible detector for use with a differential electrical mobility classifier (3.2.7).
Note 3 to entry: In some cases, a CPC may be called a “condensation nucleus counter (CNC)”.
[SOURCE: ISO 15900:2020, 3.8, modified — “using a condensation effect to increase the size of the
aerosolized particles” has been added to the definition.]
3.2.7
differential electrical mobility classifier
DEMC
classifier that is able to select aerosol (3.2.1) particles according to their electrical mobility and pass
them to its exit
Note 1 to entry: A DEMC classifies aerosol particles by balancing the electrical force on each particle with its
aerodynamic drag force in an electrical field. Classified particles are in a narrow range of electrical mobility
determined by the operating conditions and physical dimensions of the DEMC, while they can have different sizes
due to difference in the number of charges that they have.
[SOURCE: ISO 15900:2020, 3.11]
3.2.8
differential mobility analysing system
DMAS
system to measure the size distribution of sub-micrometre aerosol (3.2.1) particles consisting of
a differential electrical mobility classifier (3.2.7), flow meters, a particle detector, interconnecting
plumbing, a computer and suitable software
[SOURCE: ISO 15900:2020, 3.12]
3.2.9
nano-object
material with one, two or three external dimensions in the nanoscale (3.2.10)
Note 1 to entry: Generic term for all discrete nanoscaled objects.
[SOURCE: ISO/TS 80004-2:2015, 2.2, modified — “discrete piece of” has been deleted from the start of
the definition and the Note 1 to entry has been replaced.]
3.2.10
nanoscale
size range approximately from 1 nm to 100 nm
Note 1 to entry: Properties that are not extrapolations from a larger size will typically, but not exclusively, be
exhibited in this size range. For such properties, the size limits are considered approximate.
ISO/TS 12025:2021(E)
Note 2 to entry: The lower limit in this definition (approximately 1 nm) is introduced to avoid single and small
groups of atoms from being designated as nano-objects (3.2.9) or elements of nanostructures, which could be
implied by the absence of a lower limit.
[SOURCE: ISO/TS 80004-2:2015, 2.1, modified — Note 1 to entry has been replaced and Note 2 to entry
has been added.]
3.2.11
agglomerate
collection of loosely bound particles or aggregates (3.2.12) or mixtures of the two held together by
weak forces where the resulting external surface area is similar to the sum of the surface areas of the
individual components
Note 1 to entry: The weak forces, for example, are van der Waals forces or simple physical entanglement.
Note 2 to entry: Agglomerates are secondary particles and the original source particles are primary particles.
[SOURCE: ISO/TS 80004-2:2015, 3.4, modified — “loosely bound particles or aggregates or mixtures of
the two held together by weak forces” has replaced “weakly or medium strongly bound particles” the
notes to entry have been reworded.]
3.2.12
aggregate
particle comprising strongly bonded or fused particles held together by strong forces where the
resulting external surface area is significantly smaller than the sum of calculated surface areas of the
individual components
Note 1 to entry: The strong forces, for example, are covalent bonds, or those resulting from sintering or complex
physical entanglement.
Note 2 to entry: Aggregates are secondary particles and the original source particles are primary particles.
[SOURCE: ISO/TS 80004-2:2015, 3.5, modified — “held together by strong forces” and “calculated” have
been added to the definition and the notes to entry have been reworded.]
3.2.13
dustiness
propensity of materials to produce airborne dust during handling
Note 1 to entry: For the purpose of this document, dustiness is derived from the amount of dust emitted during a
standard test procedure.
Note 2 to entry: Dustiness is not an intrinsic property as it depends on how it is measured.
[SOURCE: EN 1540:2011, 2.5.1]
3.2.14
inhalable fraction
mass fraction of total airborne particles which is inhaled through the nose and mouth
[15]
Note 1 to entry: The inhalable fraction is specified in EN 481:1993 .
[SOURCE: EN 1540:2011, 2.3.1.1]
3.2.15
thoracic fraction
mass fraction of inhaled particles penetrating beyond the larynx
[15]
Note 1 to entry: The thoracic fraction is specified in EN 481:1993 .
[SOURCE: EN 1540:2011, 2.3.1.2]
4 © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
3.2.16
respirable fraction
mass fraction of inhaled particles penetrating to the unciliated airways
[15]
Note 1 to entry: The respirable fraction is specified in EN 481:1993 .
[SOURCE: EN 1540:2011, 2.3.1.3]
4  Symbols
For the purposes of this document, the symbols given in Table 1 apply.
Table 1 — Symbols
Symbol Quantity SI unit
n nano-object number release dimensionless
−1
n nano-object release rate s
t
−3
c nano-object aerosol number concentration m
n
−1
n mass specific nano-object number release kg
m
−1
n mass loss specific nano-object number release, from a treated sample with a kg
∆m
mass loss ∆m
3 1
V aerosol volume flow rate m /s
t
5  Factors influencing results of nano-object release from powders
5.1  Test generation method selection
The purpose of the planned test or experimental programme should be carefully defined during the
selection of the aerosol generation method.
Selection of the aerosol generation method depends on the following considerations:
a) the powder properties listed in Table 2;
[17][18][19]
b) the applicability of standardized dustiness test methods, see the EN 15051 series , or of
[32]
other powder treatment methods to simulate the typical powder handling process in practice
[34][37]
as well as selection of the appropriate treatment parameters.
The outcome of the planned test will be dependent on the experimental conditions selected.
EXAMPLE 1 Determination of the nano-object release of a powder to predict release of nanoparticles during
manual and automatic moderate powder handling processes (i.e. weak to moderate dispersion stress) for
industrial processing.
EXAMPLE 2 Estimation of nano-object and agglomerate/aggregate release from powder to simulate worst-
case scenarios of handling process, where a high energy input or high activation energy is applied to the powder
or during the generation of an aerosol for animal inhalation studies. Such high energy input is likely to be used
only in fully contained processes to prevent unacceptable exposures to workers.
5.2  Material properties influencing nano-object release from powder
Properties influencing the generation and measurements of aerosolized powders containing nano-
objects are summarized in Table 2. Presently, it is not necessarily easy to measure many of these
properties; however, they should be considered.
These material-specific properties of powder are relevant to test design (see Clause 6) and data
reporting (see Clause 8).
ISO/TS 12025:2021(E)
Table 2 — Representative properties influencing nano-object release from powders
Property Description
Particle size The value of the particle size depends on the sizing method and the corresponding
equivalent diameter (e.g. aerodynamic diameter, electrical mobility diameter,
equivalent area diameter).
The particle size of primary particles or aggregates will not change during the han-
dling of nanostructured powders. Particle size of agglomerates will change under
certain process and handling conditions, for example, shear stress.
The measured size distribution of particles will depend on the type of instrument. The
instrument can measure aerodynamic or mobility diameters, specific surface areas or
other parameters. The exact shape of primary particles will depend on the
manufacturing process. Nano-objects can be a small fraction of the total mass for
some materials.
Particle shape Particle shapes are found in a wide range of geometries depending on the material and
the process. Agglomerates and aggregates of nano-objects can have a fractal shape.
Adhesion forces depend on the particle shape because of the contact area.
Crystallinity Some powdered materials can exist in various crystalline states or in amorphous
form. The fraction of the crystalline phase can vary depending on the particle size.
Hygroscopicity and Interaction of the particle with moisture in the air characterized by the relative
moisture content humidity will affect the cohesion of the particles. Thus, the history of the relative
humidity of the environmental conditions used to store the powder can be important.
The hydrophobic versus hydrophilic characteristics affect dustiness because as time
goes on a hydrophilic nanomaterial such as magnesium oxide will become less dusty
as it absorbs water from the air. Some synthetic amorphous silica, on the other hand,
can be easily electrostatically charged and is readily aerosolized.
Cohesion The magnitude of adhesion forces between particles will affect the detachment of
particles as force is introduced into the system. Cohesion will affect the porosity be-
tween the particles and flowability of the powder. The tendency of the nanopowders to
sinter or agglomerate is also a consideration.
Material density The material density will affect aerosolization. For example, some tungsten oxide has
a high density and is not very dusty.
Porosity Porosity is a measure of the void spaces in a material. This includes the porosity of
primary nano-objects, agglomerates and generally the packing density of the bulk
powder.
Electrical resistivity The electrical resistance of the powder affects the ability of the system to dissipate
electrical charge.
Triboelectrics The ability of the material to generate static electricity will affect the forces within the
powder.
5.3  Test stages
A schematic overview of the test stages necessary for the quantification of nano-object release from
powders is shown in Figure 1. Based on the multitude of factors that influence sample preparation and
sample treatment and the current lack of understanding of sample treatment, this document provides
requirements on the basic conditions for the aerosol measurement stage.
6 © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
Figure 1 — Schematic overview of test stages for the quantification of nano-object release from
powders
Currently, for sample treatment, no one general method can be standardized as a requirement. Nearly all
[38]
powder studies suffer from incomplete determination of the energy input during sample treatment .
For repeatable powder treatment, four methods (rotating drum, continuous drop, small rotating
drum and vortex shaker) have been standardized for dustiness measurement of powders containing
nano-objects (see Annex B) and further devices are evaluated and recommended in the literature (see
Annex C). Annex D adds continuous treatment in technical disagglomeration principles.
6 Test requirements
6.1  General
6.1.1  Process parameters of the sampling procedure and of the measurement procedure shall be
selected with regard to the purpose of the test and to relevant material properties from Table 2.
6.1.2  The test protocol shall contain these considerations: the purpose, the procedure parameters and
the relevant material properties.
6.1.3  Agreements between the buyer and the seller should include considerations of the process
conditions simulated, an ability to relate to standard methods and the objectives of the study.
6.2  Safety assessment
6.2.1  A safety assessment shall be conducted for the materials before beginning the tests. Guidance is
[4] [13]
given in ISO/TR 13121:2011 and ISO/TR 27628:2007 .
Some nanomaterials can be toxic. The severity of the toxicity can depend on particle composition, size,
morphology and other physico-chemical properties of the material.
WARNING — A nanomaterial that is potentially explosive, pyrophoric or sensitive to ignition can
present a fire or explosive hazard. Health, safety and environmental control measures shall be
implemented to minimize and prevent exposure to airborne nanoparticles and spillage during
loading of powders, disposal of used powders and cleaning of equipment.
ISO/TS 12025:2021(E)
6.2.2  Electrical grounding is required to prevent electrostatic charge build-up. Other safety control
measures also have to be considered.
Earthing of the dispersion unit shall be carried out to avoid the risk dust explosion.
NOTE Controlled loading of transportation tubes and vessels by precipitation of particles at the beginning of
the test can ensure maximum penetration or minimum particle losses.
6.2.3  The tests should be tailored according to the hazard. The following examples are not exhaustive
but rather are representative.
EXAMPLE 1 Inert atmospheres are used for some materials and other control measures can be applied (e.g.
electrical grounding of equipment, use of antistatic mats and shoes).
EXAMPLE 2 Toxic materials are tested under appropriate controlled conditions (e.g. glove boxes or fume
cupboards) or are substituted with a non-toxic or less toxic substance. The substitute material exhibits the
significant characteristics of the materials of interest. If the substitute material is tested, it is specified how the
equivalence with the toxic material can be ensured.
6.2.4  Differential electrical mobility analysis for aerosol particles can require radioactive sources
within the measurement device. The function of the particle charge conditioner is to establish a known
size-dependent charge distribution on the sampled aerosol prior to the size classification process. This
bipolar ion concentration can be produced either by radioactive ionization of air from radioactive sources
or by corona discharge ionization or soft X-ray ionizers.
[7]
As stated in ISO 15900:2009 , the use, transportation and disposal of radioisotopes are regulated
by government authorities. Basic international standards and guidelines are, for example, set by
commissions of the United Nations such as the International Atomic Energy Agency (IAEA), the
International Commission on Radiological Protection (ICRP) and the Agreement concerning the
International Carriage of Dangerous Goods by Road (ADR), etc. The licensing, shipping and disposal
regulations that govern radioactive sources vary from nation to nation. This document can therefore
only advise all users of radioactive material that local, national and international laws and regulations
exist and shall be considered.
6.3  Sample preparation
Sample preparation procedures shall be reported, e.g. humidity conditioning of the sample and the test
equipment, sample splitting, electrostatic charging and sieving for limiting the maximum agglomerate
size of particles.
[6]
Guidance on powder sampling, sample splitting and minimum sample size is given in ISO 14488:2007 .
Additional safety precautions for nanomaterials require the sampling and sample splitting in closed
systems or within a fume cupboard.
6.4  Sample treatment
6.4.1  Dustiness generation methods
6.4.1.1  Selection of methods
Methods with controlled levels of applied energy selected to estimate the dustiness related to
nanomaterials expected in an industrial or user setting shall be based on established practice as
described in 6.4.1. Some selection criteria have been published for dustiness measurement of powders
(see Annex A).
6.4.1.2  Reference test methods
The rotating drum, small rotating drum and the continuous drop methods (see Annex B) are three of the
four reference test methods for determining health-related dustiness mass fraction and number-based
8 © ISO 2021 – All rights reserved

ISO/TS 12025:2021(E)
[21] [22]
dustiness. These methods are described in EN 17199-2:2019 , EN 17199-3:2019 and EN 17199-
[23] [24]
4:2019 . The vortex shaker is the fourth method described in EN 17199-5:2019 . Further details
are given in A.1.
6.4.1.3  Dynamic method
This method uses only milligrams of powdered material per test and is completely self-enclosed. Both
of these attributes are useful to evaluate nanoscale materials. The test apparatus consists of a glass
chamber, with an aspiration nozzle to disperse milligram quantities of test powder into the chamber,
[28]
and two samplers within the chamber to collect the dispersed dust . Airflows and sampling times
are controlled by the tester, which is connected to a vacuum source. The dust is dispersed by pulling
the dust into the glass chamber with a short and rapid application of vacuum (see Annex C). In this test,
a high energy input or high activation energy is applied to the powder. This input is adjustable by the
inlet orifice. The particle concentration generated is time-dependent.
6.4.2  Dispersing methods for aerosol generation
Continuously operating powder dispersing methods have been developed for a wide range of
applications, including generating dust for inhalation studies, filter testing and environmental
atmospheres. A number of methods have been used and are tailored to the powder and the application.
[25]
VDI 3491-3:2018 summarizes dispersing methods for solid materials and standardizes five technical
[8]
realizations, differing in metering, dispersing and state of charge of the aerosol. ISO/TR 19601
describes characteristics of such aerosol generation methods, including their advantages and
limitations.
An overview of disagglomeration principles is shown in Annex D. One method cannot cover the wide
range of different industrial applications of powders containing nano-objects, such as nanostructured
powders, and the very different flow properties of powders influencing the metering and mass flow
fluctuations of the aerosol. All these methods disperse the complete powder sample with the same
energy input and feed all generated aerosol particles to the measurement.
Comparative investigations of the three most widely used air jet dispersers showed the possibility
of using the average air velocity in the dispersion zone as the dominating adjustment parameter for
[34]
nanostructured powders .
6.4.3  Sample treatment execution and report
6.4.3.1  The description of the test method shall include specification of sample aerosolization and
disagglomeration characteristics:
a) duration of the test and the number of repeat measurements made;
NOTE 1 In general, powder samples before testing are agglomerates (particles touching other particles).
The test breaks the cohesive bonds separating particles from the agglomerates. Particles have a tendency
to re-agglomerate depending on the particle density in air, the length of the test and the cohesive forces
present, such as electrostatic charge. Therefore, the amount of disagglomeration and agglomeration differs
with each type of test.
b) type and description of treatment of the powder;
NOTE 2 In the drop test, impact on the bottom coated or uncoated with powder will affect the results.
c) inlet design of the test method.
NOTE 3 In the dynamic method, the inlet diameter can influence the agglomerate acceleration and
deceleration within the sampling chamber.
ISO/TS 12025:2021(E)
6.4.3.2  The following sample treatment parameters have an influence on the resulting particle release.
They shall be kept constant throughout the tests and between tests to achieve reproducibility of the
results. For comparison between different tests, they should be quantified.
a) Sample volume and residence time of the sample in the treatment zone. Both sample volume and
sample mass shall be recorded. To ensure reproducibility, the volume used shall be a “tamped”
volume rather than a “pour” volume. Guidance on how to determine a “tamped” volume is given in
[1] [19]
ISO 787-11 and for a “pour” sample volume in EN 15051-3:2013, Annex B .
b) Mechanical energy input to the treatment zone (e.g. air flow and pressure drop).
NOTE Research is needed on the measurement of the force or energy acting directly on the sample or
agglomerates, such as local shear stress, resulting from velocity gradients or dynamic impact.
c) Humidity, temperature and ion concentration.
d) Air volume flow through the treatment zone.
e) Particle concentration in the air during treatment (interparticle distances determine the ratio of
disagglomeration/agglomeration).
[20]
EN 17199-1:2019 specifies the conditioning of the powder. For standard testing and inter-comparison,
test materials shall be conditioned at a relative humidity (RH) of (50 ± 5) % before testing until they
reach a stable mass. For the characterization of the bulk material under workplace conditions, the bulk
material shall be sent to the organization performing the dustiness test as placed on the market or
as used by the downstream user, in air-tight containers. It shall be tested in the state in which it was
received.
[20]
The temperature should be kept at a constant 21 °C ± 3 °C (EN 17199-1:2019 ).
6.4.3.3  The test equipment should be electrically grounded.
6.4.3.4  The repeatability of the aerosolization and disagglomeration process shall be determined over
3 to 10 tests of fresh powder samples. It can be reported as minimum and maximum values in addition
to the average va
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