Workplace atmospheres - Calculation of the health-related aerosol fraction concentration from the concentration measured by a sampler with known performance characteristics

This Technical Report specifies a method for calculating and expressing the relevant aerosol fraction concentration and its confidence interval, rather than the actually measured concentration. This can be done for any sampler satisfying EN 13205:2001, Annex A.
The calculation method follows the procedure developed and described in EN 13205:2001, Annex A and Annex F. This Technical Report explains how to practically perform the calculation.

Arbeitsplatzatmosphäre - Berechnung der gesundheitsbezogenen Fraktion der Aerosolkonzentration anhand der mit einem Probenahmegerät mit bekannten Leistungseigenschaften gemessenen Konzentration

Atmosphères des lieux de travail - Calcul de la concentration en fractions d'aérosols liées à la santé à partir de la concentration mesurée à l'aide d'un dispositif de prélèvement ayant des caractéristiques de performances connues

Le présent rapport technique spécifie une méthode permettant de calculer et d’exprimer la concentration en fractions d’aérosols et son intervalle de confiance correspondant, plutôt que la concentration réellement mesurée. Cela concerne tout échantillonneur conforme à l’EN 13205:2001, Annexe A.
La méthode de calcul suit le mode opératoire élaboré et décrit dans l’EN 13205:2001, Annexe A et Annexe F. Le présent rapport technique explique comment effectuer les calculs dans la pratique.

Zrak na delovnem mestu - Izračunavanje koncentracije z zdravjem povezanih frakcij aerosolov iz koncentracije, izmerjene z vzorčevalnikom znanih delovnih karakteristik

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13-Feb-2007
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SLOVENSKI STANDARD
SIST-TP CEN/TR 15547:2008
01-marec-2008
=UDNQDGHORYQHPPHVWX,]UDþXQDYDQMHNRQFHQWUDFLMH]]GUDYMHPSRYH]DQLK
IUDNFLMDHURVRORYL]NRQFHQWUDFLMHL]PHUMHQH]Y]RUþHYDOQLNRP]QDQLKGHORYQLK
NDUDNWHULVWLN

Workplace atmospheres - Calculation of the health-related aerosol fraction concentration

from the concentration measured by a sampler with known performance characteristics

Arbeitsplatzatmosphäre - Berechnung der gesundheitsbezogenen Fraktion der
Aerosolkonzentration anhand der mit einem Probenahmegerät mit bekannten
Leistungseigenschaften gemessenen Konzentration

Atmospheres des lieux de travail - Calcul de la concentration en fractions d'aérosols

liées a la santé a partir de la concentration mesurée a l'aide d'un dispositif de

prélevement ayant des caractéristiques de performances connues
Ta slovenski standard je istoveten z: CEN/TR 15547:2007
ICS:
13.040.30
SIST-TP CEN/TR 15547:2008 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
TECHNICAL REPORT
CEN/TR 15547
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
February 2007
ICS 13.040.30
English Version
Workplace atmospheres - Calculation of the health-related
aerosol fraction concentration from the concentration measured
by a sampler with known performance characteristics

Atmosphères des lieux de travail - Calcul de la Arbeitsplatzatmosphäre - Berechnung der

concentration en fractions d'aérosols liées à la santé à gesundheitsbezogenen Fraktion der Aerosolkonzentration

partir de la concentration mesurée à l'aide d'un dispositif de anhand der mit einem Probenahmegerät mit bekannten

prélèvement ayant des caractéristiques de performances Leistungseigenschaften gemessenen Konzentration

connues

This Technical Report was approved by CEN on 4 December 2006. It has been drawn up by the Technical Committee CEN/TC 137.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, 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 and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15547:2007: E

worldwide for CEN national Members.
---------------------- Page: 2 ----------------------
CEN/TR 15547:2007 (E)
Contents Page

Foreword..............................................................................................................................................................3

Introduction .........................................................................................................................................................4

1 Scope......................................................................................................................................................5

2 Normative references............................................................................................................................5

3 Method to produce improved concentration data..............................................................................5

4 Data needed to calculate the concentration of a health-related aerosol fraction...........................6

5 Calculation method................................................................................................................................6

Annex A (informative) Numerical example of calculation...............................................................................9

Annex B (informative) Field sampling example .............................................................................................12

Bibliography ......................................................................................................................................................14

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CEN/TR 15547:2007 (E)
Foreword

This document (CEN/TR 15547:2007) 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.

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.

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CEN/TR 15547:2007 (E)
Introduction

Exposure assessment of workers to particulate matter dispersed into the air at the workplace is generally

achieved through aerosol sampling by using instruments designed for measuring health-related aerosol

fractions as defined in EN 481. EN 13205 gives a methodology to evaluate sampler performance. The

knowledge of the sampling efficiency of a sampler is used to calculate the bias and the accuracy in

concentration for log-normally distributed aerosols. Bias and accuracy maps give an overall indication on

sampler performance when sampling health-related aerosol fractions. This performance varies with particle

size distribution of sampled aerosol.

Many different samplers can be used for the same purpose, depending on local circumstances or the current

practice in the country where these measurements have to be performed. Even with samplers whose

performances are quite similar, some significant differences in measured concentrations can occur between

these samplers, depending on the aerosol measured. Furthermore, the concentration measured by a sampler

is not actually the conventional concentration even if the sampler fulfils the performance criteria stated in

EN 13205. This is due to the fact that the particle-size selectivity of the sampler does not generally coincide

exactly with the conventional sampling curve over the whole particle-size range.

In the revision of EN 482 presently under way, the uncertainty estimate of a measurement procedure should

be expanded to meet the requirements of ENV 13005 complying with GUM (ISO Guide to the expression of

Uncertainty in Measurements). This requires that all uncertainties encountered by the use of a measurement

procedure (except interlaboratory variation) have to be accounted for. For the special case of aerosol

sampling this means that the uncertainty in an expected bias of the sample due to non-ideal collection

characteristics will only be estimated for a very wide range of size distributions. The calculations presented in

this Technical Report can help to significantly reduce this uncertainty by first estimating a restricted range of

size distributions in which the sampler was actually used, and then estimate the bias uncertainty only over this

narrow range of size distributions. For an aerosol sampler, the variability due to bias is in many cases a major

component of the uncertainty.
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CEN/TR 15547:2007 (E)
1 Scope

This Technical Report specifies a method for calculating and expressing the relevant aerosol fraction

concentration and its confidence interval, rather than the actually measured concentration. This can be done

for any sampler satisfying EN 13205:2001, Annex A.

The calculation method follows the way developed and described in EN 13205:2001, Annex A and Annex F.

This Technical Report explains practically how to perform the calculation.
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.

EN 13205:2001, Workplace atmospheres — Assessment of performance of instruments for measurement of

airborne particle concentrations.
3 Method to produce improved concentration data

The method is based on the knowledge of sampler’s particle size-selectivity and the estimation of the aerosol

size distribution. The results with lowest uncertainty are obtained when the concentration measurements are

accompanied by measurement of aerosol size distribution. When the size distribution is not known, an

estimate can be used. The accuracy of this estimation will have a direct influence on the confidence interval of

the concentration value. The estimation of particle size distribution is not an easy exercise, however in many

cases the knowledge of the aerosol nature (mineral dust, fumes, oil mists, etc.) allows an approximate

estimation to be made.

This approach facilitates a comparison measured health-related aerosol concentrations obtained in different

European countries, whatever the samplers used.

The method cannot be used to calculate the respirable aerosol fraction from the thoracic aerosol fraction, or

vice versa.

Using the aerosol concentration measured by a sampler and the information provided by the application of

EN 13205, it is possible to calculate the concentration of the aerosol conventional fraction of interest and

therefore to assess the exposure as mentioned in EN 689 independently of the sampler used. This calculation

method leads to less bias relative to the intended conventional health-related aerosol fraction (see [1]).

Using the calculation described in this document is not compulsory. However, there are several circumstances

when using the proposed method could help to obtain higher quality results from routine aerosol

measurements. Of course, there is no need to use this calculation when the selectivity of the aerosol sampler

meets exactly the conventional target curve, i.e. its performance is ideal for all particle sizes.

More accurate values of aerosol concentrations related to some conventional fraction can be needed in some

special cases:

 in epidemiological studies consistent exposure data from old and recent periods of time are

simultaneously required in order to be correlated with human health effects;

 when data from various sampling techniques and different countries need to be interpreted. The proposed

method helps to make the results of measurements more consistent by recalculating them in terms of

concentrations of the relevant health-related aerosol fraction. The method allows a comparison of

exposures measured at different times and work places provided the performances of the samplers used

are known.
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CEN/TR 15547:2007 (E)

Another case where the proposed method can be useful is the measurement of aerosol concentrations in the

vicinity of Limit Values. A Limit Value for an aerosol concentration in the workplace is not defined as

concentration measured by some sampling device but precisely as a concentration of one of three

conventional health-related aerosol fractions (see EN 481). The method is an approach to assess the right

concentration to be compared with its Limit Value.

In the case of simultaneous measurements with two or several different samplers, the measured values from

all techniques can be processed with the proposed calculation method. The common part of the individual

confidence intervals represents a narrower confidence interval of the conventional concentration than that of

any individual measurement. The confidence interval improvement is achieved even when the sampler

performances are rather poor.

The calculations suggested in this document will not reduce the variability in measured concentration due to

the inherent variability of the concentration at a workplace

4 Data needed to calculate the concentration of a health-related aerosol fraction

a) Data from the laboratory evaluation of the sampler performance according to EN 13205:2001, Annex A.

The evaluation gives the particle size dependent sampling bias (∆) along with its standard deviation due

to the experimental method σ(∆).

b) Workplace sampling data as sampled particle mass (M), sampling flow rate (Q) and time of sampling (t)

along with the standard deviation of the analytical method e.g. weighing, σ(M), and the relative standard

deviation of the flow rate, RSD(Q).

c) Distribution of particle mass vs. particle aerodynamic diameter of sampled aerosol, measured or

estimated. This could be a log-normal distribution expressed by parameters MMAD and GSD (Mass

Median Aerodynamic Diameter and Geometric Standard Deviation) as written in EN 13205. When the

aerosol size distribution is measured at the workplace (e.g. using a cascade impactor), single values of

the MMAD and the GSD will be determined. When the size-distribution measurement cannot be provided,

the estimation of these parameters can be expressed as intervals: [MMAD – MMAD ] and [GSD –

min max min
GSD ], where MMAD < 25 µm.
max max

NOTE In some cases the workplace aerosol is better represented by a bi-modal particle size distribution. The bi-

modal distribution can be modelled by two combined uni-modal distributions and a parameter “k” from the range [0;1]

representing the relative weight of each mode . If the distribution function of the first mode is Y =ƒ(D) and the distribution

function of the second mode is Y =ƒ(D), the bi-modal aerosol distribution Y can be written as:

Y = kY +()1 −k Y (1)
1 2

The more precise the knowledge of the sampler performance and aerosol size-distribution data is, the less

uncertainty there will be in the estimated concentration of the health-related aerosol fraction. Quality of

sampling performance data may vary with the sampled aerosol fraction. Sampling the respirable and thoracic

fractions is less wind-dependent and therefore, the experimental sampling efficiency measurements are

generally of higher quality for these fractions than for the inhalable fraction. This is due to the high inertia of

coarse particles involved in the inhalable aerosol sampling.
5 Calculation method

The concentration C* of a specified conventional fraction of an aerosol is given by:

* *
C =Cf (D)E (D)dD (2)
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CEN/TR 15547:2007 (E)
where
C is the total aerosol concentration;
f the particle-size mass distribution;

E* is the function defining the conventional probability for particles to penetrate some compartments of

the respiratory airways (see EN 481).

f and E are functions of particle aerodynamic diameter D. Any actual sampler (index i) is characte

...

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