Workplace exposure - Measurement of exposure by inhalation of nano-objects and their aggregates and agglomerates - Metrics to be used such as number concentration, surface area concentration and mass concentration

This European Standard specifies the use of different metrics for the measurement of exposure by inhalation of NOAA during a basic assessment and a comprehensive assessment, respectively, as described in EN 17058 [1].
This document demonstrates the implications of choice of particle metric to express the exposure by inhalation to airborne NOAA, e.g. released from nanomaterials  and present the principles of operation, advantages and disadvantages of various techniques that measure the different aerosol metrics.
Potential problems and limitations are described and need to be addressed when occupational exposure limit values might be adopted in the future and compliance measurements will be carried out.
Specific information is mainly given for the following metrics/measurement techniques:
-   Number/Condensation Particle Counters by optical detection;
-   Number size distribution/differential mobility analysing systems by electrical mobility;
-   Surface area/electrical charge on available particle surface;
-   Mass/chemical analyses (e.g. Inductively Coupled Plasma atomic Mass Spectrometry (ICP-MS), X-Ray Fluorescence (XRF)) on size-selective samples (e.g. by impaction or diffusion).
This document is intended for those responsible for selecting measurement methods for occupational exposure to airborne NOAA.

Exposition am Arbeitsplatz - Messung der inhalativen Exposition gegenüber Nanoobjekten und deren Aggregaten und Agglomeraten - Zu verwendende Metriken wie Anzahlkonzentration, Oberflächenkonzentration und Massenkonzentration

Diese Europäische Norm legt die Anwendung verschiedener Metriken für die Messung der Exposition durch Einatmen gegenüber NOAA während einer grundlegenden und einer umfassenden Beurteilung nach EN 17058 [1] fest.
Dieses Dokument demonstriert die Auswirkungen der Wahl der Partikelmetrik, um die Exposition durch Einatmen gegenüber luftgetragenen NOAA zum Ausdruck zu bringen, die z. B. aus Nanomaterialien  frei¬gesetzt werden, und zeigt die Arbeitsweisen sowie die Vor- und Nachteile der verschiedenen Techniken auf, mit denen die verschiedenen Aerosolmetriken gemessen werden.
Mögliche Probleme und Einschränkungen werden beschrieben und sind zu beachten, wenn die Grenz-werte der maximalen Arbeitsplatzkonzentration künftig angenommen werden könnten und Messungen in Bezug auf deren Einhaltung durchgeführt werden.
Besondere Informationen werden vor allem für die folgenden Metriken/Messverfahren gegeben:
-   Anzahlkonzentration/Kondensationspartikelzähler durch optischen Nachweis;
-   Anzahlgrößenverteilung/differentielle Mobilitätsanalysesysteme durch elektrische Mobilität;
-   Oberfläche/elektrische Ladung auf der zur Verfügung stehenden Partikeloberfläche;
-   Masse/chemische Analysen (z. B. durch Massenspektrometrie mit induktiv gekoppeltem Plasma [en: Inductively Coupled Plasma atomic Mass Spectrometry, ICP MS], Röntgenfluoreszenzanalyse [en: X Ray Fluorescence, XRF]) an größenselektiven Proben (z. B. durch Impaktion oder Diffusion).
Dieses Dokument ist für diejenigen vorgesehen, die für die Auswahl von Messverfahren für die berufsbedingte Exposition gegenüber NOAA verantwortlich sind.

Exposition sur les lieux de travail - Mesurage de l'exposition par inhalation de nano-objets et de leurs agrégats et agglomérats - Métriques à utiliser telles que concentration en nombre, concentration en surface et concentration en masse

La présente Norme européenne spécifie l’utilisation de différentes métriques pour le mesurage de l’exposition par inhalation de NOAA lors d'une évaluation de base et d'une évaluation complète, respectivement, comme décrit dans l’EN 17058 [1].
Le présent document démontre les conséquences du choix d'une métrique de particules pour exprimer l'exposition par inhalation aux NOAA en suspension dans l'air, par exemple du fait de la mise en suspension de nanomatériaux  ), et présente les principes de fonctionnement, les avantages et les inconvénients de diverses techniques permettant de mesurer les différents paramètres des aérosols.
Les problèmes et limites potentiels sont décrits et doivent être traités lorsque des valeurs limites d'exposition professionnelle sont susceptibles d'être adoptées dans le futur et des mesures de conformités réalisées.
Des informations spécifiques sont données essentiellement pour les principales métriques/techniques de mesure suivantes :
-   nombre/Compteurs de Particules à Condensation par détection optique ;
-   distribution granulométrique en nombre/systèmes d'analyse différentielle de mobilité électrique ;
-   surface/charge électrique sur la surface disponible des particules ;
-   masse/analyses chimiques (par exemple spectrométrie de masse à plasma couplé par induction (ICP-MS), fluorescence X (XRF)) d'échantillons sélectifs en taille (par exemple par impaction ou diffusion).
Le présent document s'adresse aux personnes responsables du choix des méthodes de mesure de l'exposition professionnelle aux NOAA en suspension dans l'air.

Izpostavljenost na delovnem mestu - Merjenje izpostavljenosti pri vdihavanju nanopredmetov ter njihovih agregatov in aglomeratov - Uporaba metrik, kot so številčna koncentracija, masna koncentracija in koncentracija površine

Ta evropski standard podaja smernice glede vplivov na izbiro metrike delcev za izražanje izpostavljenosti nanoaerosolom, predstavlja načela delovanja, prednosti in slabosti različnih tehnik, ki merijo te metrike aerosolov, ter opisuje morebitne težave in omejitve.

General Information

Status
Published
Publication Date
13-Nov-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
14-Nov-2018
Completion Date
14-Nov-2018

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.UãLQHExposition am Arbeitsplatz - Messung der inhalativen Exposition gegenüber Nanoobjekten und deren Aggregaten und Agglomeraten - Zu verwendende Metriken wie Anzahlkonzentration, Oberflächenkonzentration und MassenkonzentrationExposition sur les lieux de travail - Mesurage de l'exposition par inhalation de nano-objets et de leurs agrégats et agglomérats - Métriques à utiliser telles que concentration en nombre, concentration en surface et concentration en masseWorkplace exposure - Measurement of exposure by inhalation of nano-objects and their aggregates and agglomerates - Metrics to be used such as number concentration, surface area concentration and mass concentration13.040.30Kakovost zraka na delovnem mestuWorkplace atmospheresICS:Ta slovenski standard je istoveten z:EN 16966:2018SIST EN 16966:2019en01-januar-2019SIST EN 16966:2019SLOVENSKI

STANDARD
SIST EN 16966:2019
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16966
November
t r s z ICS
s uä r v rä u r English Version

Workplace exposure æ Measurement of exposure by inhalation of nanoæobjects and their aggregates and agglomerates æ Metrics to be used such as number concentrationá surface area concentration and mass concentration Exposition sur les lieux de travail æ Mesurage de l 5exposition par inhalation de nanoæobjets et de leurs agrégats et agglomérats æ Métriques à utiliser telles que concentration en nombreá concentration en surface et concentration en masse

Exposition am Arbeitsplatz æ Messung der inhalativen Exposition gegenüber Nanoobjekten und deren Aggregaten und Agglomeraten æ Zu verwendende Metriken wie Anzahlkonzentrationá Oberflächenkonzentration und MassenkonzentrationThis European Standard was approved by CEN on

t y August
t r s zä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Rue de la Science 23,
B-1040 Brussels

t r s z CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s x { x xã t r s z ESIST EN 16966:2019
EN 16966:2018 (E) 2 Contents

Page European foreword ....................................................................................................................................................... 5 Introduction .................................................................................................................................................................... 6 1 Scope .................................................................................................................................................................... 7 2 Normative references .................................................................................................................................... 7 3 Terms and definitions ................................................................................................................................... 7 4 Symbols and abbreviations ...................................................................................................................... 12 5 Relevance of ISO definition for assessing health impacts of airborne NOAA ......................... 13 6 Particle metrics and their selection ...................................................................................................... 13 6.1 Workplace aerosols consisting of NOAA .............................................................................................. 13 6.2 NOAA metrics ................................................................................................................................................. 14 6.3 NOAA number metric, NOAA surface area metric and NOAA mass metric .............................. 14 6.4 Occupational exposure limits for NOAA .............................................................................................. 15 7 Exposure assessment strategy based on EN 17058 ......................................................................... 15 7.1 General ............................................................................................................................................................. 15 7.2 Basic assessment according to EN 17058 ............................................................................................ 16 7.3 Comprehensive assessment according to EN 17058 ....................................................................... 16 7.4 Personal samplers versus static samplers/monitors ..................................................................... 17 8 Determination of exposure ...................................................................................................................... 17 8.1 General ............................................................................................................................................................. 17 8.2 Introductory remarks regarding the measurement of particle metrics .................................. 18 8.2.1 General ............................................................................................................................................................. 18 8.2.2 Continuous measurement and display (using a monitor) or post-sampling analytical determination of a NOAA metric ............................................................................................................ 19 8.2.3 Calculation/estimation of a NOAA metric based on the size-resolved NOAA distribution .................................................................................................................................................... 20 8.2.4 Calculation of NOAA mass ensemble metric based on the size-resolved NOAA mass metric ............................................................................................................................................................... 20 8.3 Information of the measurement of particle metrics ..................................................................... 20 Annex A (informative)

Source domains of workplace exposure scenarios for engineered/ manufactured NOAA .................................................................................................................................... 21 Annex B (informative)

Evolution of available instrumental technology since the publication of ISO/TR 27628 and ISO/TR 12885 ............................................................................. 22 Annex C (informative)

Direct-reading instruments for measuring the NOAA ensemble number metric .............................................................................................................................................. 23 C.1 General ............................................................................................................................................................. 23 C.2 Condensation particle counter ................................................................................................................ 23 C.2.1 Principle of operation ................................................................................................................................. 23 C.2.2 Assumptions, limits and potential problems ..................................................................................... 23 C.2.3 Accuracy and comparability according to EN 16897 ...................................................................... 24 SIST EN 16966:2019

EN 16966:2018 (E) 3 C.2.4 International standards on the use of CPC .......................................................................................... 24 C.3 Diffusion chargers ........................................................................................................................................ 24 C.3.1 General ............................................................................................................................................................. 24 C.3.2 Assumptions, limits and potential problems ...................................................................................... 24 C.3.3 Accuracy and comparability ..................................................................................................................... 25 Annex D (informative)

Monitors for measuring the NOAA ensemble surface area metric ............ 26 D.1 General ............................................................................................................................................................. 26 D.2 Assumptions, limits and potential problems ...................................................................................... 26 D.3 Accuracy and comparability ..................................................................................................................... 28 Annex E (informative)

Samplers for determining the NOAA mass (chemical element) metric by off-line analysis ......................................................................................................................... 29 E.1 General ............................................................................................................................................................. 29 E.2 Ensemble of all sampled particles analysed ....................................................................................... 29 E.2.1 General ............................................................................................................................................................. 29 E.2.2 Assumptions, potential problems and comparability ..................................................................... 30 E.3 Individual particles analysed ................................................................................................................... 30 E.3.1 General ............................................................................................................................................................. 30 E.3.2 Assumptions, potential problems and comparability ..................................................................... 30 Annex F (informative)

Monitors for measuring the size-resolved NOAA number metric (number-weighted electric mobility equivalent diameter distribution) ................................. 31 F.1 General ............................................................................................................................................................. 31 F.2 DMAS of various designs ............................................................................................................................ 31 F.2.1 General ............................................................................................................................................................. 31 F.2.2 Assumptions, potential problems and comparability ..................................................................... 31 F.2.3 International Standards on the use of DMAS ...................................................................................... 32 Annex G (informative)

Samplers for determining the size-resolved NOAA mass metric (mass-weighted diffusive equivalent diameter distribution) by off-line analysis ............... 33 G.1 General ............................................................................................................................................................. 33 G.2 Diffusion spectrometers ............................................................................................................................. 33 G.2.1 General ............................................................................................................................................................. 33 G.2.2 Assumptions and potential problems ................................................................................................... 33 Annex H (informative)

Samplers for determining the size-resolved NOAA mass (chemical element/ compound) metric (mass-weighted aerodynamic equivalent diameter distribution) by off-line analysis............................................................................................................. 34 H.1 General ............................................................................................................................................................. 34 H.2 Cascade impactors ........................................................................................................................................ 34 H.2.1 General ............................................................................................................................................................. 34 H.2.2 Assumptions and potential problems ................................................................................................... 34 SIST EN 16966:2019

EN 16966:2018 (E) 4 Annex I (informative)

Monitors for determining the size-resolved NOAA number metric (number-weighted aerodynamic equivalent diameter distribution) ....................................... 35 I.1 General ............................................................................................................................................................. 35 I.2 Assumptions and potential problems ................................................................................................... 35 Annex J (informative)

Number-weighted minimum Feret diameter distribution of primary particles of aggregates and constituent parts of aggregates ........................................................ 36 J.1 Distinction between a NOAA and a non-NOAA particle .................................................................. 36 J.2 Aggregates and agglomerates .................................................................................................................. 36 J.3 Sample analysis in an electron microscope ........................................................................................ 36 J.3.1 General ............................................................................................................................................................. 36 J.3.2 Assumptions and potential problems ................................................................................................... 37 Bibliography ................................................................................................................................................................. 38

SIST EN 16966:2019

EN 16966:2018 (E) 5 European foreword This document (EN 16966:2018) 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 European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2019, and conflicting national standards shall be withdrawn at the latest by May 2019. 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 has been prepared under a standardization request given to CEN by the European Commission and the European Free Trade Association. According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16966:2019

EN 16966:2018 (E) 6 Introduction Historically, workers’ occupational exposure to airborne non-radioactive particles has been expressed as mass concentrations. The main exception has been fibres of various compositions that have been given as a number concentration for fibres within specified diameter and length limits. Other exceptions are units of glycine per cubic metre for enzymes and number of colony-forming units for airborne microbiological organisms. Engineered/manufactured nanomaterials are now being used on a wide scale. Only for a few nanomaterials is there currently large enough knowledge of which parameters of the exposure are critical for specific health end-points. Scientific documents for the elaboration of OELs for airborne nano-objects and their aggregates and agglomerates (NOAA) greater than 100 nm are limited, and nano-object specific legally binding Occupational Exposure Limits (OELs) have not been established. However, for some NOAA recommended OELs have been published. Currently, there is no overall agreement on the metric of occupational exposure to airborne NOAA. Nevertheless, all existing legally binding OELs are respected, as substances in their non-nanoscale or microscale form may have recognised OELs. Concentrations of airborne particles can be expressed as a number, surface area or mass concentrations. For spherical particles these are mathematically related to the integral over all particle sizes of the number of particles (per size) times the corresponding particle size raised to zero, two and three, respectively. The different expressions of particle concentrations are generally referred to as different metrics. Instruments used for the determination of concentrations of airborne particles are generally based on a specific measurement principle that measures the particles in only one of the metrics. Particle concentrations given by these metrics are related to each other via the particle size distribution. In general it is difficult, not to say impossible, to recalculate a concentration given in one metric into another if the complete size distribution is not known and the particles are not spherical or of varying/unknown effective density. It is therefore important that the user of measurement data on occupational exposure to NOAA understands the concepts of particle metrics. For comprehensive exposure assessments of NOAA, it is recommended that the occupational exposure is determined in parallel for more than one metric, as it is presently unknown which metric later will be considered as most relevant for the critical health effect. SIST EN 16966:2019

EN 16966:2018 (E) 7 1 Scope This European Standard specifies the use of different metrics for the measurement of exposure by inhalation of NOAA during a basic assessment and a comprehensive assessment, respectively, as described in EN 17058 [1]. This document demonstrates the implications of choice of particle metric to express the exposure by inhalation to airborne NOAA, e.g. released from nanomaterials1 and present the principles of operation, advantages and disadvantages of various techniques that measure the different aerosol metrics. Potential problems and limitations are described and need to be addressed when occupational exposure limit values might be adopted in the future and compliance measurements will be carried out. Specific information is mainly given for the following metrics/measurement techniques: — Number/Condensation Particle Counters by optical detection; — Number size distribution/differential mobility analysing systems by electrical mobility; — Surface area/electrical charge on available particle surface; — Mass/chemical analyses (e.g. Inductively Coupled Plasma atomic Mass Spectrometry (ICP-MS), X-Ray Fluorescence (XRF)) on size-selective samples (e.g. by impaction or diffusion). This document is intended for those responsible for selecting measurement methods for occupational exposure to airborne NOAA. 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 1540, Workplace exposure — Terminology 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 1540 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — IEC Electropedia: available at http://www.electropedia.org/ — ISO Online browsing platform: available at http://www.iso.org/obp 3.1 agglomerate collection of weakly bound particles or aggregates or mixtures of the two where the resulting external surface area is similar to the sum of the surface areas of the individual components Note 1 to entry: The forces holding an agglomerate together are weak forces, for example van der Waals forces, or simple physical entanglement.

1 Currently, the EU has a recommendation for a definition of nanomaterial [SOURCE: Official Journal of the European Union L275/38, 20 October 2011]. In this document the ISO definition on nanomaterial is used. SIST EN 16966:2019

EN 16966:2018 (E) 8 Note 2 to entry: Agglomerates are also termed secondary particles and the original source particles are termed primary particles. [SOURCE: CEN ISO/TS 80004-2:2017, 3.4] [2] 3.2 aggregate particle comprising strongly bonded or fused particles where the resulting external surface area can be significantly smaller than the sum of calculated surface areas of the individual components Note 1 to entry: The forces holding an aggregate together are strong forces, for example covalent bonds, or those resulting from sintering or complex physical entanglement. Note 2 to entry: Aggregates are also termed secondary particles and the original source particles are termed primary particles. [SOURCE: CEN ISO/TS 80004-2:2017, 3.5] 3.3 background airborne particles particles which occur at the time and position where samples are taken or measurements are carried out using different metrics of NOAA but which have another origin or source than the NOAA under investigation Note 1 to entry: Ultrafine particles are a subset of the background airborne particles. 3.4 BET method method for the determination of the total specific external and internal surface area of disperse powders and/or porous solids per unit of mass by measuring the amount of physically adsorbed gas utilizing the model developed by Brunauer, Emmett and Teller for interpreting gas adsorption isotherms Note 1 to entry: Method originates from Brunauer, Emmett and Teller [3]. Note 2 to entry: Inaccessible pores are not detected. The BET method cannot reliably be applied to solids that absorb the measuring gas. [SOURCE ISO 9277:2010] [4] 3.5 coagulation process caused by relative motion between particles which causes particles to collide with each other and thereafter adhering to one another Note 1 to entry:

For nanoscale particles, Brownian diffusion is the dominant source of relative motion between particles, whereas for particles of significantly different sizes, the corresponding settling velocities can be the dominant source. Coagulation leads to a reduction in the number concentration of airborne particles and a simultaneous increase in particle size. The mass concentration remain unaffected by coagulation, and for solid particles, the surface area concentration also remain unaffected by coagulation. 3.6 coincidence simultaneous occurance of two particles in the sensing zone of an instrument which are registered as one (possibly larger) particle SIST EN 16966:2019

EN 16966:2018 (E) 9 3.7 equivalent density effective density ratio of mass of an agglomerate/aggregate to the volume of a sphere defined by an equivalent diameter of the same agglomerate/aggregate Note 1 to entry: The effective density generally decreases as the size of an agglomerate/aggregate increases. 3.8 equivalent spherical diameter diameter of a sphere that produces a response by a given particle-sizing method, which is equivalent to the response produced by the particle being measured Note 1 to entry: The physical property to which the equivalent diameter refers is indicated using a suitable subscript (see ISO 9276-1). [SOURCE: CEN ISO/TS 80004-2:2017, A.2.3] 3.9 Feret diameter distance between two parallel tangents on opposite sides of the image of a particle [SOURCE: ISO 26824, 8.6] [5] 3.10 incidental nano-object nano-object generated as an unintentional by-product of a process Note 1 to entry: The process includes manufacturing, biotechnological or other processes. Note 2 to entry:

The term ultrafine particles is often used to describe unintentionally produced nano-objects. [SOURCE: CEN ISO/TS 80004-2:2017, 4.3, modified — Note 2 has been added] 3.11 material density particle material density ratio of particle mass to particle volume excluding all pores, voids and other gas containing compartments 3.12 median diameter median particle diameter particle size of a particle distribution for which one-half the total number of particles are larger and one-half are smaller [SOURCE: ISO 16972:2010, 3.47] [6] 3.13 metric airborne metric NOAA metric concentration metric amount of a selected NOAA characteristic in which the particle concentration is expressed SIST EN 16966:2019

EN 16966:2018 (E) 10 3.14 monitor real-time monitor instrument that continuously measures an entity and for the purpose of the measurements instantaneously displays/ records the measured value Note 1 to entry: The relevant instruments typically report a value every second or even faster. Instruments with a time resolution of 1 min up to several minutes are usually termed quasi-real-time. 3.15 nanomaterial material with any external dimensions in the nanoscale or having internal structure or surface structure in the nanoscale [SOURCE: CEN ISO/TS 80004-1:2015, 2.4] [7] 3.16 nano-object discrete piece of material with one, two or three external dimensions in the nanoscale Note 1 to entry: The second and third external dimensions are orthogonal to the first dimension and to each other. [SOURCE: CEN ISO/TS 80004-1: 2015, 2.5] 3.17 nanoscale length range approximately from 1 nm to 100 nm Note 1 to entry:

Properties that are not extrapolations from larger sizes are predominantly exhibited in this length range. [SOURCE: CEN ISO/TS 80004-1: 2015, 2.1] 3.18 particle minute piece of matter with defined physical boundaries Note 1 to entry: A physical boundary can also be described as an interface. Note 2 to entry: A particle can move as a unit. Note 3 to entry: This general particle definition applies to nano-objects. Note 4 to entry:

The physical phase of the particle can be either solid or liquid. [SOURCE: ISO 26824:2013, 1.1, modified — Note 4 has been added] SIST EN 16966:2019

EN 16966:2018 (E) 11 3.19 particle aerodynamic diameter particle aerodynamic equivalent diameter aerodynamic equivalent diameter aerodynamic diameter dae diameter of a sphere of 1 g/cm3 density with the same terminal settling velocity in calm air as the particle, under the prevailing conditions of temperature, pressure and relative humidity Note 1 to entry: The particle aerodynamic diameter of a particle depends on the size, density and shape of the particle. Note 2 to entry: In the human respiratory tract, the separation of particles with an aerodynamic diameter smaller than approximately 0,4 µm is better characterized by the particle diffusive equivalent diameter. [SOURCE: EN 1540:2011, 2.3.2, modified — Further admitted terms, letter symbol and Note 2 have been added] 3.20 particle diffusive diameter particle diffusive equivalent diameter diffusive equivalent diameter diffusive diameter DEPRECATED: thermodynamic diameter dde diameter of a sphere with the same diffusion coefficient as the particle under prevailing condition of temperature and pressure within the respiratory tract Note 1 to entry: The weak dependence of the particle diffusive diameter on the relative humidity is neglected [2]. Note 2 to entry: The particle diffusive diameter is applicable to any particle, regardless of its shape and is independent of the density of the particle. Note 3 to entry: For spherical particles, the particle diffusive diameter equals the geometric diameter. Note 4 to entry:

For particles with aerodynamic diameter above approximately 0,4 diameter becomes more significant in characterizing deposition than particle diffusive diameter. [SOURCE: EN ISO 13138:2012, 3.2, modified — 'Particle diffusive diameter" introduced as new preferred term, further admitted terms added, term 'thermodynamic diameter' referred as deprecated] [8] 3.21 particle mobility diameter particle mobility equivalent diameter mobility equivalent diameter mobility diameter dme diameter of a sphere carrying a single elementary charge with the same drift speed i

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