CEN/TS 18117:2025

SLOVENSKI STANDARD
01-oktober-2024
Izpostavljenost na delovnem mestu - Določanje in karakterizacija lebdečih
nanopredmetov ter njihovih agregatov in aglomeratov (NOAA) z elektronsko
mikroskopijo - Pravila za vzorčenje in analizo
Workplace exposure - Detection and characterization of airborne NOAA using electron
microscopy - Rules for sampling and analysis
Exposition am Arbeitsplatz - Nachweis und Charakterisierung von luftgetragenen NOAA
durch Elektronenmikroskopie - Regeln für Probenahme und Analyse
Exposition sur le lieu de travail - Détection et caractérisation des NOAA en suspension
dans l'air par microscopie électronique - Règles d'échantillonnage et d'analyse
Ta slovenski standard je istoveten z: FprCEN/TS 18117
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 18117
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
August 2024
ICS 13.040.30
English Version
Workplace exposure - Detection and characterization of
airborne NOAA using electron microscopy - Rules for
sampling and analysis
Exposition sur le lieu de travail - Détection et Exposition am Arbeitsplatz - Nachweis und
caractérisation des NOAA en suspension dans l'air par Charakterisierung von luftgetragenen NOAA durch
microscopie électronique - Règles d'échantillonnage et Elektronenmikroskopie - Regeln für Probenahme und
d'analyse Analyse
This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 137.
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, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a Technical Specification.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 18117:2024 E
worldwide for CEN national Members.

FprCEN/TS 18117:2024 (E)
Contents Page
European foreword. 3
Introduction . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Abbreviations . 9
5 Procedure . 10
6 Sampling . 13
7 Analysis . 14
8 Calculation of results . 31
9 Test report . 35
Annex A (informative) Apparatus and materials . 37
Annex B Annex B (informative) Round Robin on LAR-particles . 46
Annex C (informative) Round Robin of Fibres . 63
Annex D Annex D (informative) Round Robin of sampling efficiencies . 91
Annex E (informative) Examples of objects typically found on aerosol samples from workplaces
and how to characterise and count them . 105
Annex F (informative)  Value tables . 120
Bibliography . 124

FprCEN/TS 18117:2024 (E)
European foreword
This document (FprCEN/TS 18117:2024) has been prepared by Technical Committee CEN/TC 137
“Assessment of workplace exposure to chemical and biological agents”, the secretariat of which is held by DIN.
This document is currently submitted to the Vote on TS.
This document has been prepared under a standardization request addressed to CEN by the European
Commission.
FprCEN/TS 18117:2024 (E)
Introduction
Methods to assess exposure to nano objects and their agglomerates and aggregates (NOAA) in the workplace
are only partially standardized, for example the metrics to be used for exposure assessment, the tiered
approach to collect exposure measurements, the way to operate the condensation particle counter (CPC),
approach to assess dermal exposure to nanomaterials. In addition, many guidelines are rather outdated by
not outlining the requirements to identify nanoforms, as the technical standards by the time of their
formulation were not sufficient to detect nanoscale dimensions or nanoforms were not regarded of special
interest. To determine workplace exposure to particulate matter, gravimetric methods were established that
weigh the collected dust to determine mass load and a respective mass concentration for a compliance test
against occupational exposure limit values (OELV). However, those methods are insensitive towards the
particle size and in case only the fraction of NOAA needs to be determined, electron microscopy (EM) is a
necessary supplemental technique for the identification and physical characterization of NOAA, including
nanofibres (e.g. carbon nanotubes (CNTs), nanoplates (e.g. graphene) and nanoparticles. With the help of
energy dispersive X-ray spectroscopy (EDS/EDX) as an add-on to EM, also chemical identification of NOAA
can be accomplished. EM methods referred to in this document include scanning electron microscopy (SEM)
and transmission electron microscopy (TEM), which are two different techniques with different capabilities.
Fibres are of special interest, since their potential hazard can arise from their length and diameter, calling for
geometrical characterization of high aspect ratio particles found in the collected workplace aerosol with EM
techniques. In fact, the WHO established a fibre counting convention that identifies fibres in case
length > 5 µm, diameter < 3 µm and aspect ratio > 3 (WHO-fibres). Legal OELV for fibres are based on this
counting convention. However, the diameter had also a lower limit of 200 nm, accounting for the resolution
limit of phase contrast microscopy commonly used in the time when these Standards for asbestos exposure
assessment were written. Consequently, nanofibres would not be detected and counted. However, the past 20
years of nanotoxicological research attributed asbestos-like hazard potential to some nanofibres like carbon
nanotubes, which in parallel became increasingly used at workplaces. Therefore, newer guidelines and
standards for fibre workplace exposure assessment decreased or cut the lower diameter limit and
implemented the application of EM methods. Nanoparticles of non-fibrous materials indicate a higher toxicity
in comparison to micro sized particles due to the higher chemically active surface to mass ratio.
Even though no NOAA-specific legal OELV exist by the time of the formulation of this document, so-called
health-based nano reference values (HNRVs) for occupational exposure have been proposed for some
engineered nanomaterials (ENM). Especially in mixed dust environments, a quantitative analysis with EM
would have great added value for respective compliance tests, because of the possibility to distinguish
different morphological particle types, i.e. nanofibres versus other shapes. Chemical analysis included in the
EM methodology would allow for a complete identification of ENM against a complex particle background.
Thus, the application of EM analyses for assessing the actual type of exposure can be envisaged for all
workplaces dealing with nanoobjects, e.g. producers of nanoparticles and also companies subsequently
employing nanoparticles in different products. Furthermore, due to the production of unwanted nanoobjects
during processes including heat or mechanical treatments an assessment of the possible exposure might be
favourable. The EM analysis can unambiguously identify the nature and chemical identity of the nanoobjects
and thus contribute to a complete workplace exposure assessment.
EM analysis relies on aerosol collection methods to produce samples that comprise particles that can be firstly
visualized and secondly characterized. Both perquisites call for aerosol collection protocols specially adjusted
for the technical boundary conditions of the used EM as well as the analytical procedure that includes image
acquisition and subsequent particle counting as well as the measurement of selected particle parameters.
For aerosol collection, several types of samplers exist, based on different collection principles (e.g. filtration,
impaction, electrostatic- or thermophoretic precipitation) and collecting different size ranges of particles.
However, the analysis of NOAA by EM has strict requirements for samples, which leads to the use of specific
methods of sample collection and preparation. Despite the different requirements of SEM and TEM that affect
the way samples are collected and prepared for analysis, it is necessary for both techniques to collect
FprCEN/TS 18117:2024 (E)
homogeneous deposits, with a minimum of overlapping of the particles. Furthermore, the particles on the
collection medium should be in the same particle size range to which workers are potentially exposed to, from
single nano-objects to micron sized agglomerates and aggregates.
EM analysis also comes with strict requirements in particular in the context of testing the workplace aerosol
against a specific OELV, which are specific to particle types. Hence the technicalities of the analysis would be
adjusted to be optimal to identify, count and characterize the chosen particle type. In addition, the statistical
requirements in order to be confident towards the compliance test result call for strict rules. In turn, general
characterization of the workplace atmosphere to “get an idea” of its particle type composition would call for
boundary conditions allowing to visualize, count and analyse all kinds of nano-objects on the sample but
without being bound to strict statistical requirements. Generally, applicable protocols for EM analysis of
workplace samples should therefore set the rules for image acquisition, particle identification, counting and
characterization based on the analytical aim. A modular formulation of an EM protocol might enable this
strategy.
A set of validated sampling devices and collection media with experimentally determined collection and
sampling efficiencies are presented in this document, together with a set of validated protocols and guidelines
for the characterization and quantification of the airborne concentration of nanoparticles, nanofibres and
nanoplatelets and their agglomerates and aggregates using EM methods.
The methodology could be implemented as a higher tier step in an occupational exposure assessment strategy
for NOAA. Results from this analysis can be used to compare to health-based limit values, as they become
available and to understand potential health risks of workers.
NOTE Examples of direct reading instruments are CPC, SMPS, ELPI; these instruments are listed in the OECD
guideline [1].
FprCEN/TS 18117:2024 (E)
1 Scope
This document provides rules for workplace sampling and the sample analysis for the determination and
characterization of airborne NOAA for electron microscopy and includes:
— the choice of appropriate samplers and their use for the determination and characterization (e.g.
classification of structures and morphology) of airborne NOAA using electron microscopic methods (SEM
and (S)TEM);
— counting rules and criteria for the determination and characterization (e.g. classification of structures,
chemical composition and morphology) of airborne NOAA using electron microscopic methods (SEM and
(S)TEM), especially for nanofibres and platelets.
This document is based on extensive laboratory tests for airborne NOAA, in particular those released during
the handling of engineered nanomaterials.
2 Normative references
The fo
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