Ambient air - Determination of the particle number size distribution of atmospheric aerosol using a Mobility Particle Size Spectrometer (MPSS)

This document describes a standard method for determining particle number size distributions in ambient air in the size range from 10 nm to 800 nm at total concentrations up to approximately 10^5 cm^-3 with a time resolution of a few minutes. The standard method is based on a Mobility Particle Size Spectrometer (MPSS) used with a bipolar diffusion charger and a Condensation Particle Counter (CPC) as the detector. The document describes the performance characteristics and minimum requirements of the instruments and equipment to be used, and describes sampling, operation, data processing and QA/QC procedures, including calibration.

Außenluft - Bestimmung der Partikelanzahlgrößenverteilung des atmosphärischen Aerosols mit einem Mobilitäts-Partikelgrößenspektrometer (MPSS)

Dieses Dokument beschreibt ein Standardverfahren zur Ermittlung von Partikelanzahlgrößenverteilungen in Außenluft im Größenbereich von 10 nm bis 800 nm bei Gesamtkonzentrationen bis etwa 10^5 cm^−3 mit einer zeitlichen Auflösung von wenigen Minuten. Das Standardverfahren beruht auf einem Mobilitäts-Partikelgrößen¬spektrometer (MPSS), das mit einem bipolaren Diffusionsauflader sowie einem Kondensations¬partikelzähler (CPC) als Detektor betrieben wird. Dieses Dokument legt die Leistungskenngrößen und Mindestanforderungen an zu verwendende Geräte und Ausrüstung fest und beschreibt Probenahme, Betrieb, Datenverarbeitung und QA/QC Maßnahmen, einschließlich Kalibrierung.

Air ambiant - Détermination de la distribution granulométrique de particules d’un aérosol atmosphérique à l’aide d’un spectromètre de granulométrie à mobilité électrique (MPSS)

Le présent document décrit une méthode normalisée de détermination des distributions granulométriques de particules dans l’air ambiant dans la gamme de tailles allant de 10 nm à 800 nm à des concentrations totales allant jusqu’à environ 10^5 cm^-3 avec une résolution temporelle de quelques minutes. La méthode normalisée repose sur un spectromètre de granulométrie à mobilité électrique (MPSS) associé à un chargeur à diffusion bipolaire et à un compteur de particules à noyaux de condensation (CPC) pour la détection. Le présent document décrit les caractéristiques de performance et les exigences minimales relatives aux instruments et au matériel à utiliser, ainsi que les procédures de prélèvement, d’utilisation, de traitement des données, et d’assurance qualité et de contrôle qualité, y compris l’étalonnage.

Zunanji zrak - Določevanje spektra velikosti delcev atmosferskih aerosolov s spektrometrom na osnovi mobilnosti (MPSS)

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Status
Published
Publication Date
31-Mar-2020
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
01-Apr-2020
Completion Date
01-Apr-2020

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SLOVENSKI STANDARD
SIST-TS CEN/TS 17434:2020
01-junij-2020
Zunanji zrak - Določevanje spektra velikosti delcev atmosferskih aerosolov s
spektrometrom na osnovi mobilnosti (MPSS)

Ambient air - Determination of the particle size spectra of atmospheric aerosol using a

Mobility Particle Size Spectrometer (MPSS)
Außenluft - Bestimmung des Partikelgrößenspektrums des atmosphärischen Aerosols
mit einem Partikelgrößenmobilitätsspektrometer (MPSS)

Air ambiant - Détermination de la distribution granulométrique de particules d’un aérosol

atmosphérique à l’aide d’un spectromètre de granulométrie à mobilité électrique (MPSS)

Ta slovenski standard je istoveten z: CEN/TS 17434:2020
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
SIST-TS CEN/TS 17434:2020 en,de

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

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SIST-TS CEN/TS 17434:2020
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SIST-TS CEN/TS 17434:2020
CEN/TS 17434
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
April 2020
TECHNISCHE SPEZIFIKATION
ICS 13.040.20
English Version
Ambient air - Determination of the particle number size
distribution of atmospheric aerosol using a Mobility
Particle Size Spectrometer (MPSS)
Air ambiant - Détermination de la distribution Außenluft - Bestimmung der

granulométrique de particules d'un aérosol Partikelanzahlgrößenverteilung des atmosphärischen

atmosphérique à l'aide d'un spectromètre de Aerosols mit einem Mobilitäts-
granulométrie à mobilité électrique (MPSS) Partikelgrößenspektrometer (MPSS)

This Technical Specification (CEN/TS) was approved by CEN on 22 December 2019 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17434:2020 E

worldwide for CEN national Members.
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SIST-TS CEN/TS 17434:2020
CEN/TS 17434:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 5

Introduction .................................................................................................................................................................... 6

1 Scope .................................................................................................................................................................... 7

2 Normative references .................................................................................................................................... 7

3 Terms and definitions ................................................................................................................................... 7

4 Symbols and abbreviations ......................................................................................................................... 8

5 Atmospheric aerosol ...................................................................................................................................... 8

6 Description of the method ........................................................................................................................ 10

6.1 Sampling and conditioning ....................................................................................................................... 10

6.1.1 Sampling .......................................................................................................................................................... 10

6.1.2 Aerosol Drying .............................................................................................................................................. 11

6.2 Determination of particle number size distribution with an MPSS ........................................... 12

6.2.1 Physical principle ......................................................................................................................................... 12

6.2.2 Particle charging .......................................................................................................................................... 12

6.2.3 Mobility analysis........................................................................................................................................... 12

6.2.4 Data inversion ............................................................................................................................................... 16

6.2.5 Correction for particle losses due to diffusion .................................................................................. 16

6.2.6 Correction for CPC detection efficiency ............................................................................................... 16

7 MPSS performance criteria and test procedures .............................................................................. 17

7.1 MPSS design and performance criteria ................................................................................................ 17

7.2 Test procedures for MPSS performance criteria .............................................................................. 18

7.2.1 Actual aerosol flow rate ............................................................................................................................. 18

7.2.2 Particle size range ........................................................................................................................................ 18

7.2.3 Particle size calibration accuracy .......................................................................................................... 19

7.2.4 Accuracy of integrated particle number concentration ................................................................. 19

7.2.5 False background number concentration ........................................................................................... 19

7.2.6 Flow condition ............................................................................................................................................... 19

7.2.7 Accuracy of the particle number size distribution........................................................................... 20

8 Performance criteria and test procedures for the sampling and conditioning system ...... 20

8.1 General requirements ................................................................................................................................ 20

8.2 Performance characteristics and criteria ........................................................................................... 20

8.3 Particle losses due to diffusion ............................................................................................................... 21

8.4 Relative humidity ......................................................................................................................................... 21

8.5 Dilution factor ............................................................................................................................................... 21

8.6 Primary sampling flow ............................................................................................................................... 22

9 Measurement procedure ........................................................................................................................... 22

9.1 Measurement planning .............................................................................................................................. 22

9.2 Environmental operating conditions .................................................................................................... 22

9.3 Initial installation ........................................................................................................................................ 22

9.4 Initial checks on site.................................................................................................................................... 22

9.5 Data reporting ............................................................................................................................................... 23

10 Quality control, quality assurance and measurement uncertainty ........................................... 24

10.1 General ............................................................................................................................................................. 24

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10.2 General operating procedures ................................................................................................................. 24

10.3 Frequency of calibrations, checks and maintenance ....................................................................... 24

10.3.1 General ............................................................................................................................................................. 24

10.3.2 Aerosol flow rate calibration (MPSS) .................................................................................................... 25

10.3.3 Aerosol flow rate calibration (CPC) ....................................................................................................... 25

10.3.4 Humidity, temperature and pressure sensors calibration ............................................................ 26

10.3.5 CPC calibration .............................................................................................................................................. 26

10.3.6 Delay time check ........................................................................................................................................... 26

10.3.7 Mean false background concentration check (CPC) ......................................................................... 26

10.3.8 Leak check ....................................................................................................................................................... 26

10.3.9 Sampling system maintenance ................................................................................................................ 26

10.3.10 Humidity sensor calibration ............................................................................................................ 26

10.3.11 Dilution factor calibration (where applicable) ......................................................................... 26

10.3.12 Leak check ............................................................................................................................................... 26

10.4 Measurement uncertainty ......................................................................................................................... 27

Annex A (normative) Bipolar charge distribution ......................................................................................... 28

Annex B (normative) Calculation of particle losses due to diffusion ...................................................... 30

B.1 General equations and constants ............................................................................................................ 30

B.2 Particle losses due to diffusion in straight tubes of circular cross section .............................. 31

B.3 Particle losses due to diffusion in a MPSS ............................................................................................ 32

Annex C (informative) Example of the calculation of particle losses due to diffusion in a

sampling system ............................................................................................................................................ 33

C.1 Description of the sampling system ....................................................................................................... 33

C.2 Air properties and diffusion coefficient ............................................................................................... 34

C.3 Losses in the primary sampling tube .................................................................................................... 34

C.4 Particle losses due to diffusion in the secondary sampling tube and the MPSS .................... 35

C.5 Overall sampling losses .............................................................................................................................. 36

Annex D (informative) Example of an MPSS design ...................................................................................... 37

Annex E (informative) Dilution system ............................................................................................................. 39

E.1 Background ..................................................................................................................................................... 39

E.2 Criteria for dilution systems ..................................................................................................................... 39

E.3 Design example of a dilution system ..................................................................................................... 39

E.4 Operating parameters of a dilution system ........................................................................................ 40

E.5 Example for the calculation of the uncertainty of the dilution factor ....................................... 42

Annex F (informative) Laminar flow .................................................................................................................. 45

Annex G (informative) Data reporting ............................................................................................................... 46

G.1 Motivation ....................................................................................................................................................... 46

G.2 Level 0 (annotated raw data) ................................................................................................................... 47

G.3 Level 1 (data processed to final physical property, potential corrections applied,

original temporal resolution) .................................................................................................................. 47

G.4 Level 2 (hourly averages, including measures of variability) ...................................................... 47

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G.5 Implementation in ACTRIS / EMEP / GAW .......................................................................................... 47

G.6 Data and Metadata Included in Level 0 ................................................................................................ 48

G.6.1 Data ................................................................................................................................................................... 48

G.6.2 Metadata .......................................................................................................................................................... 49

G.6.3 Flags .................................................................................................................................................................. 51

G.7 Data and Metadata Included in Level 1 ................................................................................................ 51

G.7.1 Data ................................................................................................................................................................... 51

G.7.2 Metadata .......................................................................................................................................................... 51

G.7.3 Flags .................................................................................................................................................................. 54

G.8 Data and Metadata Included in Level 2 ................................................................................................ 54

G.8.1 Data ................................................................................................................................................................... 54

G.8.2 Metadata .......................................................................................................................................................... 55

G.8.3 Flags .................................................................................................................................................................. 57

Annex H (informative) Atmospheric aerosols in Europe ............................................................................ 58

H.1 General ............................................................................................................................................................. 58

H.2 Mean concentrations .................................................................................................................................. 58

H.3 Examples of measurements...................................................................................................................... 59

Bibliography ................................................................................................................................................................. 62

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CEN/TS 17434:2020 (E)
European foreword

This document (CEN/TS 17434:2020) has been prepared by Technical Committee CEN/TC 264 “Air

quality”, 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.

According to the CEN/CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
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CEN/TS 17434:2020 (E)
Introduction

There is a growing awareness of the significance of aerosol particles with diameters of D < 1 µm for

human health as well as for their climatic impact. To assess air quality, it appears necessary to

supplement gravimetrically determined mass concentrations such as PM or PM with a measurement

10 2.5

of the particle number concentration. Since ultrafine particles with diameters of D < 0,1 µm make an

almost insignificant contribution to the mass concentration of atmospheric aerosol particles, they can

best be detected with counting measuring methods of sufficient sensitivity.

As particle measurement instrumentation allows determining either the particle number concentration

or the particle number size distribution two Technical Specifications have been established:

— one dealing with the determination of the single parameter number concentration (a measure of

“total” number concentration (CEN/TS 16976)),

— one dealing with the determination of number concentrations within a limited number of size ranges

(this document).

Clauses 5 and 6 contain general information about the method and the expected properties of the aerosol

particles to be measured.

Clause 7 sets out the performance criteria for MPSSs. Specifically, these are the relevant performance

characteristics of MPSS instruments (without any sampling system), the respective criteria that shall be

met, and a description of how the tests shall be carried out. In general these tests are expected to be

carried out by test houses or MPSS manufacturers rather than users, and could form the basis for type

approval of MPSSs in future.

Clause 8 sets out the performance criteria and test procedures for the sampling and conditioning system.

These may be applied by manufacturers of sampling systems, test houses or users (network operators).

Clause 9 sets out requirements for the installation, initial checks and calibrations, and operation of an

MPSS and sampling system at a monitoring site, including routine maintenance, data processing

(including use of QA/QC data) and reporting. In general these will be the responsibility of users (network

operators), though calibrations requiring test aerosols shall only be carried out by suitably qualified

laboratories.

Clause 10 sets out Quality Assurance and Quality Control procedures, i.e. the ongoing checks and

calibrations that are required on the MPSS and sampling system during operation at a monitoring site. It

is expected that these will be the responsibility of users (network operators). The main sources of

measurement uncertainty are described, but it is not possible in this document to quantify the overall

measurement uncertainty for data reported following the method.
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1 Scope

This document describes a standard method for determining particle number size distributions in

ambient air in the size range from 10 nm to 800 nm at total concentrations up to approximately

5 –3

10 cm with a time resolution of a few minutes. The standard method is based on a Mobility Particle

Size Spectrometer (MPSS) used with a bipolar diffusion charger and a Condensation Particle Counter

(CPC) as the detector. The document describes the performance characteristics and minimum

requirements of the instruments and equipment to be used, and describes sampling, operation, data

processing and QA/QC procedures, including calibration.
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.

CEN/TS 16976:2016, Ambient air — Determination of the particle number concentration of atmospheric

aerosol

ISO 15900, Determination of particle size distribution — Differential electrical mobility analysis for aerosol

particles

ISO 27891:2015, Aerosol particle number concentration — Calibration of condensation particle counters

3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 https://www.iso.org/obp/ui
3.1
aerosol

multi-phase system of solid and/or liquid particles suspended in a gas, ranging in particle size from

0,001 µm to 100 µm
[SOURCE: CEN/TS 16976:2016]
3.2
detection efficiency

ratio of the particle number concentration determined by the measuring instrument to the reference

particle number concentration of the aerosol at the instrument's inlet
[SOURCE: CEN/TS 16976:2016, modified]
3.3
number size distribution

frequency distribution of the particle number concentration represented as a function of the logarithm

of particle size, such that the area under the distribution between two sizes is the number concentration

of that size range
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CEN/TS 17434:2020 (E)
3.4
particle
small piece of matter with defined physical boundary

Note 1 to entry: The phase of a particle can be solid, liquid, or between solid and liquid and a mixture of any of the

phases.
[SOURCE: ISO 27891:2015, modified]
3.5
particle number concentration
number of particles related to the unit volume of the carrier gas

Note 1 to entry: For the exact particle number concentration indication, information on the gaseous condition

(temperature and pressure) or the reference to a standard volume indication is necessary.

Note 2 to entry: The usual unit is cm .
[SOURCE: ISO 27891:2015, modified]
4 Symbols and abbreviations
CPC Condensation Particle Counter
DMA Differential Mobility Analyser
HEPA High Efficiency Particulate Air
MPSS Mobility Particle Size Spectrometer
PSL Polystyrene Latex
QA/QC Quality Assurance / Quality Control
5 Atmospheric aerosol

Atmospheric aerosols are strongly dependent on their local and regional sources. Especially, the size

distributions in number and mass, as well as the size-resolved chemical composition are highly variable.

Aerosol particles are either emitted directly (primary aerosols) or formed by nucleation and

condensation from pre-cursor gases (secondary aerosol). Combustion processes lead to both primary

and secondary aerosols [1].

Due to these different formation processes the size distribution of the atmospheric aerosol shows three

to four different modes which schematically are sketched in Figure 1.
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CEN/TS 17434:2020 (E)
Key
1 Nucleation mode I Ultrafine particles
2 Aitken mode II Fine particles
3 Accumulation mode III Coarse particles
4 Coarse mode

Figure 1 — Schematic representation of the different modes of the size distribution of

atmospheric aerosols (mode height not to scale)

Particles in the nucleation mode are mainly produced by photochemical reactions and by mixing

processes from gaseous precursors. If supply of gaseous precursors persists, they grow rapidly by

condensation so that their size is shifted into the Aitken mode. Combustion processes contribute particles

directly to the Aitken mode. The size of the particles in the Aitken mode increases mainly by cloud

processing, condensation and coagulation, so that they are shifted into the accumulation mode. Particles

in the coarse mode are mainly produced by mechanical processes like the abrasion and resuspension of

mineral dust, dispersion of sea salt as particles and emission of pollen and other biological material. Both

the accumulation and the coarse mode particles are often not clearly recognizable in the number

distribution but contribute substantially to the mass distribution.

Besides these definitions used in the field of atmospheric physics there are the health and regulatory

definitions of fine, ultrafine and coarse particles. The size ranges associated with these terms are also

given in Figure 1.

Mass-wise, the global direct emission of aerosol particles is dominated by sea salt, biological material as

well as by desert and volcanic dust. These particles are generally larger than 1 µm (coarse mode).

Anthropogenic emissions in this size range play a minor role on a global scale. Submicrometer natural

aerosols consist mainly of marine sulphate, biogenic organics, and wildfire carbonaceous particles.

Submicrometer anthropogenic aerosols are complex mixtures of primary and secondary particles,

consisting mainly of sulphate, nitrate, organics and elemental carbon.
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CEN/TS 17434:2020 (E)

Particle number concentrations of atmospheric aerosols cover several orders of magnitude. While remote

marine or free tropospheric aerosols have number concentrations as low as tens or a few hundred per

cubic centimetre, continental or urban aerosols can contain a few thousand up to one million particles

per cubic centimetre. The number concentration of the anthropogenic aerosols over land, especially in

urban areas is dominated by particles in the size range smaller than 0,1 µm. Major sources for high

particle number concentrations in this size range are regional new particle formation due to

homogeneous nucleation and local combustion processes. Average background concentrations in an

urban area are several tens of thousands of particles per cubic centimetre.
For details see Annex H.
6 Description of the method
6.1 Sampling and conditioning
6.1.1 Sampling
The measurement of atmospheric aeroso
...

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17434:2019
01-oktober-2019
Zunanji zrak - Določevanje spektra velikosti delcev atmosferskih aerosolov s
spektrometrom na osnovi mobilnosti (MPSS)

Ambient air - Determination of the particle size spectra of atmospheric aerosol using a

Mobility Particle Size Spectrometer (MPSS)
Außenluft - Bestimmung des Partikelgrößenspektrums des atmosphärischen Aerosols
mit einem Partikelgrößenmobilitätsspektrometer (MPSS)
Ta slovenski standard je istoveten z: FprCEN/TS 17434
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
kSIST-TS FprCEN/TS 17434:2019 en,de

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

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kSIST-TS FprCEN/TS 17434:2019
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kSIST-TS FprCEN/TS 17434:2019
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17434
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
August 2019
ICS
English Version
Ambient air - Determination of the particle size spectra of
atmospheric aerosol using a Mobility Particle Size
Spectrometer (MPSS)
Außenluft - Bestimmung des Partikelgrößenspektrums
des atmosphärischen Aerosols mit einem
Partikelgrößenmobilitätsspektrometer (MPSS)

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee

CEN/TC 264.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

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

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 17434:2019 E

worldwide for CEN national Members.
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kSIST-TS FprCEN/TS 17434:2019
FprCEN/TS 17434:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 5

Introduction .................................................................................................................................................................... 6

1 Scope .................................................................................................................................................................... 7

2 Normative references .................................................................................................................................... 7

3 Terms and definitions ................................................................................................................................... 7

4 Symbols and abbreviations ......................................................................................................................... 8

5 Atmospheric aerosol ...................................................................................................................................... 8

6 Description of the method ........................................................................................................................ 10

6.1 Sampling and conditioning ....................................................................................................................... 10

6.1.1 Sampling .......................................................................................................................................................... 10

6.1.2 Aerosol Drying .............................................................................................................................................. 11

6.2 Determination of particle number size distribution with an MPSS ........................................... 12

6.2.1 Physical principle ......................................................................................................................................... 12

6.2.2 Particle charging .......................................................................................................................................... 12

6.2.3 Mobility analysis........................................................................................................................................... 12

6.2.4 Data inversion ............................................................................................................................................... 15

6.2.5 Correction for particle losses due to diffusion .................................................................................. 15

6.2.6 Correction for CPC detection efficiency ............................................................................................... 16

7 MPSS performance criteria and test procedures .............................................................................. 16

7.1 MPSS design and performance criteria ................................................................................................ 16

7.2 Test procedures for MPSS performance criteria .............................................................................. 18

7.2.1 Actual aerosol flow rate ............................................................................................................................. 18

7.2.2 Particle size range ........................................................................................................................................ 18

7.2.3 Particle size calibration accuracy .......................................................................................................... 18

7.2.4 Accuracy of integrated particle number concentration ................................................................. 18

7.2.5 False background number concentration ........................................................................................... 19

7.2.6 Flow condition ............................................................................................................................................... 19

7.2.7 Accuracy of the particle number size distribution........................................................................... 19

8 Performance criteria and test procedures for the sampling and conditioning system ...... 19

8.1 General requirements ................................................................................................................................ 19

8.2 Performance characteristics and criteria ........................................................................................... 20

8.3 Particle losses due to diffusion ............................................................................................................... 20

8.4 Relative humidity ......................................................................................................................................... 20

8.5 Dilution factor ............................................................................................................................................... 20

8.6 Primary sampling flow ............................................................................................................................... 21

9 Measurement procedure ........................................................................................................................... 21

9.1 Measurement planning .............................................................................................................................. 21

9.2 Environmental operating conditions .................................................................................................... 21

9.3 Initial installation ........................................................................................................................................ 21

9.4 Initial checks on site.................................................................................................................................... 22

9.5 Data reporting ............................................................................................................................................... 22

10 Quality control, quality assurance and measurement uncertainty ........................................... 23

10.1 General ............................................................................................................................................................. 23

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10.2 General operating procedures ................................................................................................................. 23

10.3 Frequency of calibrations, checks and maintenance ....................................................................... 24

10.3.1 General ............................................................................................................................................................. 24

10.3.2 Aerosol flow rate calibration (MPSS) .................................................................................................... 25

10.3.3 Aerosol flow rate calibration (CPC) ....................................................................................................... 25

10.3.4 Humidity, temperature and pressure sensors calibration ............................................................ 25

10.3.5 CPC calibration .............................................................................................................................................. 25

10.3.6 Delay time check ........................................................................................................................................... 25

10.3.7 Mean false background concentration check (CPC) ......................................................................... 25

10.3.8 Leak check ....................................................................................................................................................... 25

10.3.9 Sampling system maintenance ................................................................................................................ 25

10.3.10 Humidity sensor calibration ............................................................................................................ 26

10.3.11 Dilution factor calibration (where applicable) ......................................................................... 26

10.3.12 Leak check ............................................................................................................................................... 26

10.4 Measurement uncertainty ......................................................................................................................... 26

Annex A (normative) Bipolar charge distribution ......................................................................................... 28

Annex B (normative) Calculation of particle losses due to diffusion ...................................................... 30

B.1 General equations and constants ............................................................................................................ 30

B.2 Particle losses due to diffusion in straight tubes of circular cross section .............................. 31

B.3 Particle losses due to diffusion in a MPSS ............................................................................................ 31

Annex C (informative) Example of the calculation of particle losses due to diffusion in a

sampling system ............................................................................................................................................ 33

C.1 Description of the sampling system ....................................................................................................... 33

C.2 Air properties and diffusion coefficient ............................................................................................... 34

C.3 Losses in the primary sampling tube .................................................................................................... 34

C.4 Particle losses due to diffusion in the secondary sampling tube and the MPSS .................... 35

C.5 Overall sampling losses .............................................................................................................................. 36

Annex D (informative) Example of an MPSS design ...................................................................................... 37

Annex E (informative) Dilution system ............................................................................................................. 39

E.1 Background ..................................................................................................................................................... 39

E.2 Criteria for dilution systems ..................................................................................................................... 39

E.3 Design example of a dilution system ..................................................................................................... 39

E.4 Operating parameters of a dilution system ........................................................................................ 40

E.5 Example for the calculation of the uncertainty of the dilution factor ....................................... 42

Annex F (informative) Laminar flow .................................................................................................................. 44

Annex G (informative) Data reporting ............................................................................................................... 45

G.1 Motivation ....................................................................................................................................................... 45

G.2 Level 0 (annotated raw data) ................................................................................................................... 46

G.3 Level 1 (data processed to final physical property, potential corrections applied,

original temporal resolution) .................................................................................................................. 46

G.4 Level 2 (hourly averages, including measures of variability) ...................................................... 46

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G.5 Implementation in ACTRIS / EMEP / GAW .......................................................................................... 46

G.6 Data and Metadata Included in Level 0 ................................................................................................ 47

G.6.1 Data ................................................................................................................................................................... 47

G.6.2 Metadata .......................................................................................................................................................... 48

G.6.3 Flags .................................................................................................................................................................. 50

G.7 Data and Metadata Included in Level 1 ................................................................................................ 50

G.7.1 Data ................................................................................................................................................................... 50

G.7.2 Metadata .......................................................................................................................................................... 50

G.7.3 Flags .................................................................................................................................................................. 53

G.8 Data and Metadata Included in Level 2 ................................................................................................ 53

G.8.1 Data ................................................................................................................................................................... 53

G.8.2 Metadata .......................................................................................................................................................... 53

G.8.3 Flags .................................................................................................................................................................. 56

Annex H (informative) Atmospheric aerosols in Europe ............................................................................ 57

H.1 General ............................................................................................................................................................. 57

H.2 Mean concentrations .................................................................................................................................. 57

H.3 Examples of measurements...................................................................................................................... 58

Bibliography ................................................................................................................................................................. 61

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European foreword

This document (FprCEN/TS 17434:2019) has been prepared by Technical Committee CEN/TC 264 “Air

quality”, the secretariat of which is held by DIN.
This document is currently submitted to the Formal Vote.
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Introduction

There is a growing awareness of the significance of aerosol particles with diameters of D < 1 µm for

human health as well as for their climatic impact. To assess air quality, it appears necessary to

supplement gravimetrically determined mass concentrations such as PM or PM with a measurement

10 2.5

of the particle number concentration. Since ultrafine particles with diameters of D < 0,1 µm make an

almost insignificant contribution to the mass concentration of atmospheric aerosol particles, they can

best be detected with counting measuring methods of sufficient sensitivity.

As particle measurement instrumentation allows determining either the particle number concentration

or the particle number size distribution two Technical Specifications have been established:

— one dealing with the determination of the single parameter number concentration (a measure of

“total” number concentration (CEN/TS 16976)),

— one dealing with the determination of number concentrations within a limited number of size ranges

(this document).

Clauses 5 and 6 contain general information about the method and the expected properties of the aerosol

particles to be measured.

Clause 7 sets out the performance criteria for MPSSs. Specifically, these are the relevant performance

characteristics of MPSS instruments (without any sampling system), the respective criteria that shall be

met, and a description of how the tests shall be carried out. In general these tests are expected to be

carried out by test houses or MPSS manufacturers rather than users, and could form the basis for type

approval of MPSSs in future.

Clause 8 sets out the performance criteria and test procedures for the sampling and conditioning system.

These may be applied by manufacturers of sampling systems, test houses or users (network operators).

Clause 9 sets out requirements for the installation, initial checks and calibrations, and operation of an

MPSS and sampling system at a monitoring site, including routine maintenance, data processing

(including use of QA/QC data) and reporting. In general these will be the responsibility of users (network

operators), though calibrations requiring test aerosols shall only be carried out by suitably qualified

laboratories.

Clause 10 sets out Quality Assurance and Quality Control procedures, i.e. the ongoing checks and

calibrations that are required on the MPSS and sampling system during operation at a monitoring site. It

is expected that these will be the responsibility of users (network operators). The main sources of

measurement uncertainty are described, but it is not possible in this document to quantify the overall

measurement uncertainty for data reported following the method.
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1 Scope

This document describes a standard method for determining particle number size distributions in

ambient air in the size range from 10 nm to 800 nm at total concentrations up to approximately

5 –3

10 cm with a time resolution of a few minutes. The standard method is based on a Mobility Particle

Size Spectrometer (MPSS) used with a bipolar diffusion charger and a Condensation Particle Counter

(CPC) as the detector. The document describes the performance characteristics and minimum

requirements of the instruments and equipment to be used, and describes sampling, operation, data

processing and QA/QC procedures, including calibration.
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.

CEN/TS 16976:2016, Ambient air - Determination of the particle number concentration of atmospheric

aerosol

ISO 15900:2009, Determination of particle size distribution — Differential electrical mobility analysis for

aerosol particles

ISO 27891:2015, Aerosol particle number concentration — Calibration of condensation particle counters

3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
aerosol

multi-phase system of solid and/or liquid particles suspended in a gas, ranging in particle size from

0,001 µm to 100 µm
[SOURCE: CEN/TS 16976:2016]
3.2
detection efficiency

ratio of the particle number concentration determined by the measuring instrument to the reference

particle number concentration of the aerosol at the instrument's inlet
[SOURCE: CEN/TS 16976:2016, modified]
3.3
number size distribution

frequency distribution of the particle number concentration represented as a function of the logarithm

of particle size, such that the area under the distribution between two sizes is the number concentration

of that size range
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3.4
particle
small piece of matter with defined physical boundary

Note 1 to entry: The phase of a particle can be solid, liquid, or between solid and liquid and a mixture of any of the

phases.
[SOURCE: ISO 27891:2015, modified]
3.5
particle number concentration
number of particles related to the unit volume of the carrier gas

Note 1 to entry: For the exact particle number concentration indication, information on the gaseous condition

(temperature and pressure) or the reference to a standard volume indication is necessary.

Note 2 to entry: The usual unit is cm .
[SOURCE: ISO 27891:2015, modified]
4 Symbols and abbreviations
CPC Condensation Particle Counter
DMA Differential Mobility Analyser
HEPA High Efficiency Particulate Air
MPSS Mobility Particle Size Spectrometer
PSL Polystyrene Latex
QA/QC Quality Assurance / Quality Control
5 Atmospheric aerosol

Atmospheric aerosols are strongly dependent on their local and regional sources. Especially, the size

distributions in number and mass, as well as the size-resolved chemical composition are highly variable.

Aerosol particles are either emitted directly (primary aerosols) or formed by nucleation and

condensation from pre-cursor gases (secondary aerosol). Combustion processes lead to both primary

and secondary aerosols [1].

Due to these different formation processes the size distribution of the atmospheric aerosol shows three

to four different modes which schematically are sketched in Figure 1.
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Key
1 Nucleation mode I Ultrafine particles
2 Aitken mode II Fine particles
3 Accumulation mode III Coarse particles
4 Coarse mode

Figure 1 — Schematic representation of the different modes of the size distribution of

atmospheric aerosols (mode height not to scale)

Particles in the nucleation mode are mainly produced by photochemical reactions and by mixing

processes from gaseous precursors. If supply of gaseous precursors persists, they grow rapidly by

condensation so that their size is shifted into the Aitken mode. Combustion processes contribute particles

directly to the Aitken mode. The size of the particles in the Aitken mode increases mainly by cloud

processing, condensation and coagulation, so that they are shifted into the accumulation mode. Particles

in the coarse mode are mainly produced by mechanical processes like the abrasion and resuspension of

mineral dust, dispersion of sea salt as particles and emission of pollen and other biological material. Both

the accumulation and the coarse mode particles are often not clearly recognizable in the number

distribution but contribute substantially to the mass distribution.

Besides these definitions used in the field of atmospheric physics there are the health and regulatory

definitions of fine, ultrafine and coarse particles. The size ranges associated with these terms are also

given in Figure 1.

Mass-wise, the global direct emission of aerosol particles is dominated by sea salt, biological material as

well as by desert and volcanic dust. These particles are generally larger than 1 µm (coarse mode).

Anthropogenic emissions in this size range play a minor role on a global scale. Submicrometer natural

aerosols consist mainly of marine sulphate, biogenic organics, and wildfire carbonaceous particles.

Submicrometer anthropogenic aerosols are complex mixtures of primary and secondary particles,

consisting mainly of sulphate, nitrate, organics and elemental carbon.

Particle number concentrations of atmospheric aerosols cover several orders of magnitude. While remote

marine or free tropospheric aerosols have number concentrations as low as tens or a few hundred per

cubic centimetre, continental or urban aerosols can contain a few thousand up to one million particles

per cubic centimetre. The number concentration of the anthropogenic aerosols over land, especially in

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urban areas is dominated by particles in the size range smaller than 0,1 µm. Major sources for high

particle number concentrations in this size range are regional new particle formation due to

homogeneous nucleation and local combustion processes. Average background concentrations in an

urban area are several tens of thousands of particles per cubic centimetre.
For details see Annex H.
6 Description of the method
6.1 Sampling and conditioning
6.1.1 Sampling

The measurement of atmospheric aerosols will always necessitate sampling and the transport of the

sample to the measuring instrument. Moreover, in certain cases the sample shall be processed in terms

of temperature, relative humidity and particle concentration in order to adapt the aerosol to the

measuring instrument's permissible operating conditions.

The information given on this issue in this document refers to stationary ambient monitoring sites. For

mobile applications (e.g. measurements from aircraft), additional considerations shall be taken into

account.

The measuring instruments shall be accommodated in a protected environment in controlled conditions

(temperature 20 °C to 30 °C).

The sampling location depends on the measurement task. If the undisturbed atmospheric aerosol is to be

measured, air intake should take place 5 m to 10 m above the ground level. Buildings, vegetation or the

topography of the terrain may make an even higher sampling point necessary. By contrast, the

measurement of aerosols affecting the exposure of humans (e.g. traffic) calls for much lower sampling

heights (1,5 m to 4 m above the ground, see Directive 2008/50/EC [2]).
The des
...

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