SIST EN ISO 13138:2012
(Main)Air quality - Sampling conventions for airborne particle deposition in the human respiratory system (ISO 13138:2012)
Air quality - Sampling conventions for airborne particle deposition in the human respiratory system (ISO 13138:2012)
Particle deposition criteria are presented for size-selective aerosol samplers so as to approximate the deposition efficiency of distinct areas of the human respiratory system. Sampling criteria are given for extrathoracic, tracheobronchial, and alveolar collection of both fine and ultrafine nonfibrous particles. The deposition criteria, together with a particle metric related to health-effects, such as particle surface area or mass, then determine specific sampling needs.
The criteria complement internationally accepted sampling conventions defined in terms of penetration, rather than deposition within the respiratory tract. The traditional conventions were developed around available instrumentation and particle mass, and are considered conservative indicators of exposure. However, the deposition criteria are expected to lead to better correlation between air quality assessment and adverse health effects, especially when sub-micrometer particles are significant.
The sampling criteria are necessarily approximations in view of the variety of ambient conditions and the diversity both between and within individuals given different activity levels. Despite the variations, specific reference human breathing characteristics are adopted so as to obtain definite yet meaningful criteria. The criteria, once established, are expected to stimulate instrument development and to be applied initially in health effects research.
Estimation of an uncertainty component associated with the bias between candidate and ideal sampler is outlined for the case of mass-based sampling.
Relationships between estimates from penetration as compared to deposition mass-based sampling are given in the mean over a set of particle size distributions. Such relationships are needed for historical continuity, and the associated uncertainties are indicators of the disparity between penetration and deposition.
Luftbeschaffenheit - Probenahmekonventionen für die Abscheidung luftgetragener Partikel im menschlichen Atmungssystem (ISO 13138:2012)
1.1 Dieses Dokument stellt Probenahmekonventionen zur Definition idealisierter Sammler vor, um die
Abscheidung nicht flüchtiger, nicht hygroskopischer, nicht faserförmiger Aerosole an fünf genau bezeichneten
geometrischen Orten (Loci) des Atemtrakts, die nach einem von der Internationalen Kommission für
Strahlenschutz entwickelten Modell (ICRP Modell (1994) [1]) berechnet wurden, abschätzen zu können. Bei
den fünf Orten handelt es sich um den vorderen und den hinteren Bereich des Nasengangs, den Cilien
tragenden und den nichtciliierten Teil des Tracheobronchialbereichs sowie um den Alveolar- (Gasaustausch-)-
Bereich. Die Konventionen sind unterteilt in drei unabhängige Probenahmewirkungsgrade für den
thermodynamischen Durchmesser, welche die Diffusionsbewegung (Brownsche Bewegung) von Partikeln im
Submikrometerbereich charakterisieren, und in vier Wirkungsgrade für einen aerodynamischen Durchmesser
von mehr als 0,1 μm, welche die Abscheidung durch Impaktion bzw. schwerkraftbedingte Absetzung
charakterisieren. Jeder Konventionskurve liegt das Mittel aus zwölf Abscheidungskurven für zwölf
verschiedene Atembedingungen zugrunde, die sich vom Sitzen bis zu schwerer körperlicher Anstrengung,
über männlich im Vergleich zu weiblich sowie die Atmungsart (Mundatmung im Vergleich zu nasaler Atmung)
erstrecken.
1.2 Die Konventionen ergänzen die derzeit international angewendeten in ISO 7708 festgelegten
Konventionen zum Eindringen von Partikeln (einatembare, thorakale und alveolengängige Fraktion), um in
Arbeitumgebungen die Übereinstimmung mit den zulässigen Expositionsniveaus für aerodynamische
Durchmesser von über 0,1 μm zu ermitteln.
Qualité de l'air - Conventions de prélèvement de particules aéroportées en fonction de leur dépôt dans les voies respiratoires humaines (ISO 13138:2012)
La présente Norme internationale spécifie les conventions de prélèvement destinées à définir les dispositifs de
prélèvement idéaux pour estimer le dépôt des aérosols non volatils, non hygroscopiques et non fibreux dans
cinq régions spécifiques des voies respiratoires. Ces cinq régions sont les secteurs antérieurs et postérieurs
des voies nasales, les parties ciliées et non ciliées de la région trachéo-bronchique et la région alvéolaire
(d'échange gazeux).
Les conventions sont différenciées en trois efficacités de prélèvement indépendantes définies en termes
de diamètre thermodynamique caractérisant le mouvement (brownien) de diffusion des particules
sub‑micrométriques et en quatre efficacités en termes de diamètre aérodynamique > 0,1 μm c aractérisant
le dépôt par impact, par interception ou par gravité. Chaque courbe conventionnelle a été développée en
faisant la moyenne de 12 courbes de dépôt correspondant à 12 conditions respiratoires faisant la distinction
entre l'état assis et l'exercice intense, les hommes et les femmes et les différents modes de respiration (par la
bouche ou par les narines).
NOTE Le dépôt est calculé selon un modèle développé par la Commission internationale de radioprotection (ICRP,
Référence [3]).
Kakovost zraka - Dogovorjeno vzorčenje lebdečih delcev, ki se nalagajo v človeškem respiratornem traktu (ISO 13138:2011)
Ta mednarodni standard določa dogovorjeno vzorčenje za opredelitev idealiziranih vzorčevalnikov za ocenjevanje nalaganja nehlapnih, nehigroskopičnih in nevlaknatih aerosolov v petih določenih lokusih dihalnega trakta. Pet lokusov zajema prednja in zadnja območja nosnih hodnikov, cilirane in necilirane dele sapnika in bronhijev ter območje pljučnih mehurčkov (izmenjava plina). Dogovori so razdeljeni v tri samostojne učinkovitosti vzorčenja, določene na ravni termodinamičnega premera, ki označuje difuzno (Brownovo) gibanje delcev, manjših od mikrometra in štiri učinkovitosti, določene na ravni aerodinamičnega premera >0,1 μm, ki označuje nalaganje z impakcijo, prestrezanjem ali posedanjem zaradi gravitacije. Dogovorjene krivulje so bile razvite kot povprečje 12 krivulj nalaganja, ki ustrezajo 12 dihalnim pogojem, od sedenja do naporne vadbe, glede na ženski ali moški spol in način dihanja (ustno ali nosno dihanje).
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 13138:2012
01-junij-2012
.DNRYRVW]UDND'RJRYRUMHQRY]RUþHQMHOHEGHþLKGHOFHYNLVHQDODJDMRY
þORYHãNHPUHVSLUDWRUQHPWUDNWX ,62
Air quality - Sampling conventions for airborne particle deposition in the human
respiratory system (ISO 13138:2012)
Luftbeschaffenheit - Probenahmekonventionen für die Abscheidung luftgetragener
Partikel im menschlichen Atmungssystem (ISO 13138:2012)
Qualité de l'air - Conventions de prélèvement de particules aéroportées en fonction de
leur dépôt dans les voies respiratoires humaines (ISO 13138:2012)
Ta slovenski standard je istoveten z: EN ISO 13138:2012
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
SIST EN ISO 13138:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN ISO 13138:2012
---------------------- Page: 2 ----------------------
SIST EN ISO 13138:2012
EUROPEAN STANDARD
EN ISO 13138
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2012
ICS 13.040.01
English Version
Air quality - Sampling conventions for airborne particle
deposition in the human respiratory system (ISO 13138:2012)
Qualité de l'air - Conventions de prélèvement de particules Luftbeschaffenheit - Probenahmekonventionen für die
aéroportées en fonction de leur dépôt dans les voies Abscheidung luftgetragener Partikel im menschlichen
respiratoires humaines (ISO 13138:2012) Atmungssystem (ISO 13138:2012)
This European Standard was approved by CEN on 14 January 2012.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13138:2012: E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 13138:2012
EN ISO 13138:2012 (E)
Contents Page
Foreword .3
2
---------------------- Page: 4 ----------------------
SIST EN ISO 13138:2012
EN ISO 13138:2012 (E)
Foreword
This document (EN ISO 13138:2012) has been prepared by Technical Committee ISO/TC 146 "Air quality" in
collaboration with 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 July 2012, and conflicting national standards shall be withdrawn at the
latest by July 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 13138:2012 has been approved by CEN as a EN ISO 13138:2012 without any modification.
3
---------------------- Page: 5 ----------------------
SIST EN ISO 13138:2012
---------------------- Page: 6 ----------------------
SIST EN ISO 13138:2012
INTERNATIONAL ISO
STANDARD 13138
First edition
2012-01-15
Air quality — Sampling conventions for
airborne particle deposition in the human
respiratory system
Qualité de l’air — Conventions de prélèvement de particules
aéroportées en fonction de leur dépôt dans les voies respiratoires
humaines
Reference number
ISO 13138:2012(E)
©
ISO 2012
---------------------- Page: 7 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
4.1 General . 3
4.2 Rationale for the early penetration conventions (EN 481 and ISO 7708) . 4
4.3 Need for particle deposition conventions . 4
4.4 Intended application . 4
5 Assumptions and approximations . 4
6 Deposition sampling conventions . 5
Annex A (informative) Deposition variation and its correction .10
Bibliography .16
© ISO 2012 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 13138 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace
atmospheres.
iv © ISO 2012 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
Introduction
Aerosols comprise disperse systems of particles, liquid or solid, inorganic or organic, anthropogenic or natural
in origin. They are found in all working and living environments, indoors or outdoors. The range of aerosol types
is vast. Many can be hazardous to humans when exposure occurs by inhalation, leading to a wide range of
diseases, depending on where inhaled particles are deposited in the respiratory tract. Many specific diseases
such as asthma, bronchitis, emphysema, pneumoconiosis (including coal workers’ pneumoconiosis, silicosis
and asbestosis), and lung cancer are all known to be associated with aerosol exposures by inhalation. Protection
of workers and the general public therefore requires meaningful standards by which such exposures may be
regulated. The emergence of such standards goes back to the beginning of the 1900s, and has accelerated
in the decades running up to the publication of this International Standard with increasing awareness of the
associations between exposures and disease, along with better understanding of the nature of aerosols and
exposures to them. Even very early on, the particle-size role in the penetration of particles into, and deposition
within, the respiratory tract has been acknowledged. Based on a large body of research that has been conducted
since 1960 and before, understanding of the role of particle size in the distribution of and deposition of particles
in the various regions of the respiratory tract has led to the stipulation of particle size-selective curves that
provide guidelines for the performance of sampling instruments, of the type widely used by occupational and
environmental hygienists, that may be used to measure exposures in a way that is directly relevant to any of
the health effects of interest.
The original conventions, based on experimental data from carefully controlled inhalation studies with human
volunteers, were expressed as curves describing penetration to the region of interest as a function of particle
size, latterly (since the 1960s) in terms of the metric known as particle aerodynamic diameter in the size range
extending from 0,5 μm to 100 μm. These conventions led to the emergence of samplers for collecting the inhalable,
thoracic, and respirable mass fractions of ambient airborne particles, in both working and living environments,
although the conventions are not restricted solely to mass sampling. The conventions were deliberately set
up conservatively in view of the large inter- and intra-person variation and with full acknowledgement that the
actual deposition of particles (and hence true exposure) differs from penetration, e.g. to or within the alveolar
region of the lung and other scenarios, especially when there are particularly fine aerosols. From the outset,
therefore, it was to be expected that correlations between disease and exposure might be somewhat limited.
However, such an approach readily paved the way for aerosol scientists to develop reasonably simple samplers
or monitors whose performance could adequately match the conventions of interest.
With the current availability of large amounts of information on aerosol particle deposition in the human
respiratory tract, with ongoing development of more advanced and truly representative sampling instruments,
and with research into health-effect determinants such as deposited particle surface area (as opposed to
mass), the establishment of conventions that allow for more direct estimations of actual deposition is now
justified. This International Standard provides conventions for samplers intended to represent fractions of
inhaled aerosol particles actually depositing in specific areas of the respiratory system. The particle size range
is extended below 0,1 μm where deposition is dominated by diffusion (Brownian motion).
Whether these new conventions will in fact lead to significantly improved correlation between exposure and
disease is, at the time of publication, still an open question. Nonetheless, deposition is likely to be a more
relevant potentially causative factor than one that includes exhaled particles that do not interact with the
body. Whereas the earlier conventions have already been adopted in many legal schemes for determining
compliance with exposure levels deemed safe, the newer conventions are expected to be applied initially in
forthcoming health effects research. Eventually, however, it is possible that compliance standards themselves
will be revised if suitable samplers come into use, and correlation between exposure measurements and health
effects are in fact found to be significantly improved.
© ISO 2012 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 13138:2012
---------------------- Page: 12 ----------------------
SIST EN ISO 13138:2012
INTERNATIONAL STANDARD ISO 13138:2012(E)
Air quality — Sampling conventions for airborne particle
deposition in the human respiratory system
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of the document. Users should therefore consider printing this
document using a colour printer.
1 Scope
This International Standard specifies sampling conventions to define idealized samplers for estimating the
deposition of non-volatile, non-hygroscopic, non-fibrous aerosols in five specific loci of the respiratory tract.
The five loci consist of the anterior and posterior areas of the nasal passages, the ciliated and non-ciliated
parts of the tracheobronchial area, and the alveolar (gas exchange) region.
The conventions are separated into three independent sampling efficiencies defined in terms of thermodynamic
diameter characterizing the diffusive (Brownian) motion of sub-micrometre particles and four efficiencies in
terms of aerodynamic diameter >0,1 μm characterizing deposition by impaction, interception or gravitational
settling. Each conventional curve has been developed as an average of 12 deposition curves corresponding
to 12 breathing conditions ranging from sitting to heavy exercise, male vs female, and breathing mode (mouth
vs nasal breathing).
NOTE Deposition is computed according to a model developed by the International Commission on Radiological
Protection (ICRP, Reference [3]).
2 Normative references
The following referenced documents are indispensable for the application 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 7708, Air quality — Particle size fraction definitions for health-related sampling
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
EN 481, Workplace atmospheres — Size fraction definitions for measurement of airborne particles
EN 13205, Workplace atmospheres — Assessment of performance of instruments for measurement of airborne
particle concentrations
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aerodynamic diameter
�
ae
3 �3 �3
diameter of a sphere of density � = 10 kg m = 1 g cm with the same terminal velocity due to gravitational
0
force in calm air as the particle, under the prevailing conditions of temperature, pressure and relative humidity
within the respiratory tract
NOTE 1 Adapted from ISO 7708:1995, 2.2.
NOTE 2 The aerodynamic diameter is applicable to any particle, but it is dependent on the density, shape and porosity
of the particle.
© ISO 2012 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
NOTE 3 Under the conditions of interest in this International Standard, the aerodynamic diameter of a spherical particle
is generally equal to �√(�/�), where � is the geometric diameter of the sphere. For high-density spheres of diameter of
0
the order of 0,1 μm where the corpuscular aspects of the air can be significant, a “slip”-correction factor is required (see
Reference [3]).
NOTE 4 For particles with aerodynamic diameter below approximately 0,4 µm, the thermodynamic diameter becomes
more significant in characterizing deposition than aerodynamic diameter.
3.2
thermodynamic diameter
�
th
diameter of a sphere with the same diffusion coefficient as the particle under prevailing conditions of temperature
and pressure within the respiratory tract
NOTE 1 The weak dependence of the thermodynamic diameter on the relative humidity is neglected (see Reference
[3]).
NOTE 2 The thermodynamic diameter is applicable to any particle, regardless of its shape and is independent of the
density of the particle.
NOTE 3 The thermodynamic diameter is equal to the geometric diameter for spherical particles of interest in this
International Standard.
NOTE 4 For particles of aerodynamic diameter above approximately 0,4 µm, the aerodynamic diameter becomes more
significant in characterizing deposition than thermodynamic diameter.
3.3
inhalable fraction
fraction of total airborne particles of given particle size inhaled through the nose and mouth
NOTE 1 Adapted from ISO 7708:1995, 2.3.
NOTE 2 The fractions specified in 3.3 to 3.8, as defined at specific particle size (characterized by thermodynamic and
aerodynamic diameters), are independent of the basis of measurement, e.g. mass, area or particle count.
NOTE 3 A significant portion of the inhaled particles may be exhaled, but since these are smaller particles their effect
on the mass deposited may be minimal.
3.4
extrathoracic ET deposition efficiency
1
fraction of inhaled particles of given particle size deposited in the anterior nasal passages (i.e. the entrance to
the nose itself)
NOTE 1 Particles can be deposited in the ET region directly following inhalation by the nose or indirectly from interior
1
regions of the respiratory tract upon exhalation. Particles inhaled by mouth are deposited in ET only upon exhalation.
1
NOTE 2 The nasal/oral division between inhaled particles is reflected in the conventions presented in this International
Standard by averaging over breathing habits (6.6) or by individual correction (Annex A).
3.5
extrathoracic ET deposition efficiency
2
fraction of inhaled particles of given particle size deposited in the posterior nasal passages consisting of the
larynx and pharynx
NOTE Particles can be deposited in the ET region directly following inhalation by mouth or indirectly by the nose or
2
upon exhalation.
3.6
tracheobronchial BB deposition efficiency
fraction of inhaled particles of given particle size deposited after the larynx in the trachea and bronchi from
which deposited material is cleared by ciliary action
NOTE See Reference [3] for further details.
2 © ISO 2012 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
3.7
tracheobronchial bb deposition efficiency
fraction of inhaled particles of given particle size deposited after the BB region in the bronchioles and terminal
bronchioles before the alveolar (gas exchange) region
NOTE See Reference [3] for further details.
3.8
alveolar deposition efficiency
fraction of inhaled airborne particles of given particle size deposited in the alveoli
3.9
tidal volume
�
T
volume of gas entering or leaving the lung during the inspiratory or expiratory phase
[1]
NOTE 1 Adapted from ISO 10651-4:2002 , 3.15.
NOTE 2 The tidal volume is expressed in millilitres.
3.10
breathing rate
�
number of breaths per minute
3.11
inspiratory flow rate
�
sum of the volumes of air inhaled and exhaled from a person’s lungs per time
NOTE 1 The inspiratory flow rate is expressed in millilitres per second.
NOTE 2 The inspiratory flow rate is sometimes denoted �.
NOTE 3 The inspiratory flow rate, �, is given by the equation, � = 2� �, where � is the breathing rate and � is the tidal
T T
volume.
3.12
functional residual capacity
FRC
volume of air present in the lungs at the end of expiration when extra effort is not applied
4 Principle
4.1 General
4.1.1 A large body of research has been conducted on deposition of particles within the human respiratory
system. Experience has consisted mainly of the study of physical models of the body as exposed to particles
of known size under controlled wind conditions or in tracing the fate of radioactively marked particles after
inhalation by human subjects. For a review of the various research efforts, see Reference [4]. Reference [3]
presents detailed models summarizing the experimental data.
[2] [5]
4.1.2 At the time of publication, ISO 7708, EN 481, ASTM D6062 , and ACGIH provide the only
established sampling conventions for classifying mass fractions of ambient particles (as either inhalable,
thoracic, or respirable) as to reaching specific parts of the respiratory system. The conventions are the result of
a compromise between previous definitions which were designed to approximate the fraction of dust of given
size that penetrates to (rather than deposits in) different areas of the body.
© ISO 2012 – All rights reserved 3
---------------------- Page: 15 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
4.2 Rationale for the early penetration conventions (EN 481 and ISO 7708)
4.2.1 The conventions have been established conservatively, significantly overstating the actual penetration
so as to circumvent large inter- and intra-person variation.
4.2.2 With coarse particles (� greater than about 0,5 μm), such as those found in the mining environment,
ae
the conventional respirable fraction and aerosol particles deposited in the gas-exchange region correlate well in
the mean.
4.2.3 Samplers exist for personal sampling that operate reasonably in accordance with the penetration
conventions.
4.3 Need for particle deposition conventions
4.3.1 The penetration conventions (ISO 7708, EN 481) were not set up to account for exhalation of sub-
micrometre particles that is needed to achieve correlation with health effects in some situations.
4.3.2 ISO 7708 and EN 481 did not cover increased deposition in the alveolar and extrathoracic regions as
particle diameters decrease below 0,5 μm.
4.3.3 ISO 7708 and EN 481 were set up as limits rather than estimates. The deposition conventions, no longer
designed around conservative limits (4.2.1), can increase the information obtained in a workplace assessment
and also improve the establishment of meaningful occupational exposure limits.
4.4 Intended application
4.4.1 The conventions of this International Standard may find immediate application in health-effects research
in providing improved correlation between air quality assessment and observed effects. Specifically, dose
received prior to clearance can be estimated. For example, suppose that deposited mass is the health-related
metric of interest. The estimated dose in region x, � , in milligrams, is given by:
x,D
1 m
x
mq= t (1)
x,D
2 qt
xs
where
� is the inspiratory flow rate, in millilitres per second, of a person;
� is the time, in seconds, of exposure of a person;
� is the mass sampled, in milligrams;
x
� is the sampling rate, in millilitres per second;
x
� is the sampling time, in seconds.
s
4.4.2 The acceptance of definite deposition conventions will stimulate instrument development: either for
particle size-distribution measurement (via particle-size classifiers) or for samplers dedicated specifically to the
deposition conventions (e.g. see References [6] to [12]).
5 Assumptions and approximations
5.1 Many approximations come into play in establishing sampling conventions intended to mimic deposition
of particles within the respiratory system. These may be summarized in 5.2 to 5.6.
4 © ISO 2012 – All rights reserved
---------------------- Page: 16 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
5.2 The sampling conventions given here are averages over a representative set of breathing characteristics
(see Table 1).
5.3 Particles which reach the alveoli but which are not deposited there can be deposited in the upper
respiratory tract as they pass through it during exhalation.
NOTE In the case of a cloud of particles small enough to avoid impaction or gravitational settling in the respiratory
tract, deposition can be significant in the extrathoracic region with Brownian motion during exhalation or inhalation.
5.4 The effect of the diameter change of hygroscopic particles due to accumulation of water while within the
respiratory system, though significant, for example to the deposition of soluble salts and acid mists, is beyond
the scope of this International Standard.
5.5 The effect of particle charge is not considered.
5.6 The ICRP deposition model (see Reference [3]), approximates the net particle capture probability at
each locus of the respiratory tract as the root sum of squares (RSS) of thermodynamic and aerodynamic sub-
probabilities. RSS is equivalent to a simple sum except in the overlap region from 0,1 μm to 1,0 μm, where
impaction, sedimentation, and diffusive deposition are inefficient. The non-linear combination of the deposition
probabilities is problematic to apply to a sampler. Therefore, this International Standard adopts a purely
linear approximation. Annex A provides a means for reducing inaccuracy in the overlap region by fitting linear
combinations of the sampling conventions to the RSS approximation. (See Reference [13] for more details.)
6 Deposition sampling conventions
6.1 As with EN 481 and ISO 7708, a small set of sampling conventions is defined in this International
Standard, rather than using raw models (see Reference [3]) involving a great many variable parameters. The
aim is to focus on aspects of interest. Furthermore, delimitation of the conventions is expected to concentrate
efforts towards developing practical instrumentation.
6.2 This International Standard employs functions �[�;(�,�)] and �ʹ[�;(�,�)] of (either thermodynamic or
c c
aerodynamic) diameter �. The function � is the cumulative lognormal distribution, parameterized in terms of
�
distribution constants, median cut diameter � and distribution variance �. The function �ʹ, defined as its slope
c
at diameter �, is the lognormal probability distribution function itself:
2
ln dd/
()
1
c
Fd′[;(,d σ)] ≡ exp − (2)
c
2
2πσd
2σ
Many spreadsheets and all statistical programs have dedicated sub-programs for quickly computing the
cumulative distribution function �. Alternatively, an algorithm presented in ISO 7708 may be used.
6.3 The functions � and �ʹ are useful for modelling a variety of curves. Furthermore, integration with particle
size distributions is simple. For more information about the use of lognormal functions, see Reference [13].
6.4 Aerosol particle inhalability convention
6.4.1 This International Standard specifies sampling conventions in terms of sampling efficiencies for aerosol
particles following inhalation. This is possible because the ICRP deposition model (see Reference [3]) itself
estimates deposition efficiencies after inhalation. Estimation of dose from an aerosol particle cloud then requires
pre-selection accounting for the inhalable fraction (3.3).
6.4.2 For � ≤ 1 µm, the inhalable convention shall be taken as equal to 1,00.
ae
6.4.3 The inhalable convention for � > 1 µm shall be taken as specified in ISO 7708 or EN 481, covering
ae
conditions of moderate wind (see References [14] to [16]). Also, knowledge developing at the time of publication
© ISO 2012 – All rights reserved 5
---------------------- Page: 17 ----------------------
SIST EN ISO 13138:2012
ISO 13138:2012(E)
(see References [17] to [21]) covering inhalability under conditions of the low wind speeds found in indoor
workplace environments can be assimilated as available. Acceptance in this aspect shall be in accordance w
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.