CEN/TS 17660-2:2024
(Main)Air quality - Performance evaluation of air quality sensor systems - Part 2: Particulate matter in ambient air
Air quality - Performance evaluation of air quality sensor systems - Part 2: Particulate matter in ambient air
This document specifies the general principles, including testing procedures and requirements, for the classification of performance of low-cost sensor systems for the monitoring of particulate matter in ambient air at fixed sites. The classification of sensor systems includes tests that are performed under prescribed conditions. It does not guarantee performance in locations that are different from the tests, variations in meteorological climate from the test programme or account for stability over time, which can only be assessed under ongoing quality control strategies.
The described procedure is applicable to the determination of the mass concentration of particulate matter. The pollutants that are considered in this document are PM10 and PM2,5 in the range of concentrations expected in ambient air.
This document provides a classification that is consistent with the requirements for indicative measurements and objective estimation defined in Directive 2008/50/EC. In addition, it provides a classification for applications (non-regulatory measurements) that require more relaxed performance criteria.
This document applies to sensor systems used as individual systems. It does not apply to sensor systems as part of a sensor network. However, for some applications (e.g. in cities) sensor systems are deployed as part of a sensor network. Annex A provides information on the use of sensor systems as nodes in a sensor network.
Luftbeschaffenheit - Leistungsbewertung von Luftqualitätssensorsystemen - Teil 2: Partikelförmige Stoffe in der Außenluft
Dieses Dokument legt allgemeine Grundsätze einschließlich Prüfverfahren und -anforderungen für die Klassifizierung der Leistung von kostengünstigen Sensorsystemen für die Überwachung partikelförmiger Stoffe in der Außenluft an festen Standorten fest. Die Klassifizierung von Sensorsystemen beinhaltet Prüfungen, die unter vorgeschriebenen Bedingungen durchgeführt werden. Dies garantiert nicht die Leistung an Standorten, die sich in den Prüfbedingungen oder Abweichungen des meteorologischen Klimas vom Prüfprogramm unterscheiden oder Stabilität im Verlauf der Zeit berücksichtigen, die nur im Rahmen fortlaufender Qualitätskontrollstrategien beurteilt werden kann.
Das beschriebene Verfahren ist anwendbar für die Bestimmung der Massenkonzentration von partikelförmigen Stoffen. Die in diesem Dokument berücksichtigten Stoffe sind PM10 und PM2,5 in dem in der Außenluft erwarteten Konzentrationsbereich.
Dieses Dokument bietet eine Klassifizierung, die mit den Anforderungen an indikative Messungen und objektive Schätzungen in der Richtlinie 2008/50/EG konsistent ist. Darüber hinaus liefert es eine Klassifizierung für Anwendungen (nicht-regulatorische Messungen) die entspanntere Leistungskriterien erfordern.
Dieses Dokument ist anwendbar für als einzelne Systeme verwendete Sensorsysteme. Es ist nicht anwendbar auf Sensorsysteme als Teil eines Sensornetzwerks. Für einige Anwendungen (z. B. in Städten) werden Sensorsysteme jedoch als Teil eines Sensornetzwerks eingesetzt. Anhang A enthält Informationen zur Nutzung von Sensorsystemen als Knoten in einem Sensornetzwerk.
Qualité de l'air - Évaluation des performances des systèmes capteurs de la qualité de l'air - Partie 2 : Particules dans l'air ambiant
Le présent document spécifie les principes généraux, y compris les modes opératoires d'essai et les exigences, pour la classification des performances des systèmes capteurs à faible coût dans le cadre de la surveillance de la matière particulaire dans l'air ambiant sur des sites fixes. La classification des systèmes capteurs comprend des essais réalisés dans des conditions prescrites. Il ne garantit pas de performance dans des lieux différents des essais, en cas de variations des conditions météorologiques par rapport au programme d'essai, ni ne tient compte de la stabilité dans le temps, qui ne peut être évaluée que dans le cadre de stratégies en continu de contrôle de la qualité.
Le mode opératoire décrit est applicable à la détermination de la concentration massique de matière particulaire. Les polluants pris en considération dans le présent document sont les fractions PM10 et PM2,5 dans la plage de concentrations attendues dans l'air ambiant.
Le présent document fournit une classification qui est cohérente avec les exigences de mesures indicatives et d'estimation objective définies dans la Directive 2008/50/CE. En outre, il fournit une classification pour les applications (mesures non réglementaires) qui exigent des critères de performance plus souples.
Le présent document s'applique aux systèmes capteurs utilisés en tant que systèmes individuels. Il ne s'applique pas aux systèmes capteurs faisant partie d'un réseau de capteurs. Cependant, pour certaines applications (par exemple dans les villes), les systèmes capteurs sont mis en oeuvre dans le cadre d'un réseau de capteurs. L'Annexe A fournit des informations concernant l'utilisation des systèmes capteurs en tant que noeuds dans un réseau de capteurs.
Kakovost zraka - Vrednotenje lastnosti senzorskih sistemov za kakovost zraka - 2. del: Delci v zunanjem zraku
Ta dokument določa splošna načela, vključno s preskusnimi postopki in zahtevami, za razvrščanje lastnosti nizkocenovnih senzorskih sistemov za spremljanje delcev v zunanjem zraku na fiksnih mestih. Razvrščanje senzorskih sistemov vključuje preskuse, ki se izvajajo v predpisanih pogojih. Ne zagotavlja delovanja na lokacijah, ki se razlikujejo od preskusov, so v drugačnem podnebju kot preskusni program ali zagotavljajo časovno stabilnost, kar je mogoče oceniti le s stalnim nadzorovanjem kakovosti.
Opisani postopek se uporablja za določanje masne koncentracije delcev. V tem dokumentu so obravnavana onesnaževala PM10 in PM2,5 v območju pričakovanih koncentracij v zunanjem zraku.
Ta dokument zagotavlja razvrstitev v skladu z zahtevami za indikativne meritve in objektivno oceno, ki so opredeljene v Direktivi 2008/50/ES. Poleg tega zagotavlja razvrstitev za vrste uporabe (neregulativne meritve), ki zahtevajo manj stroga merila za delovanje.
Ta dokument se uporablja za senzorske sisteme, ki se uporabljajo kot samostojni sistemi. Ne uporablja se za senzorske sisteme, ki so del senzorskega omrežja. Vendar pa so pri nekaterih vrstah uporabe (npr. v mestih) senzorski sistemi nameščeni kot del senzorskega omrežja. Dodatek A podaja informacije o uporabi senzorskih sistemov kot vozlišč v senzorskem omrežju.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2025
Kakovost zraka - Vrednotenje lastnosti senzorskih sistemov za kakovost zraka - 2.
del: Delci v zunanjem zraku
Air quality - Performance evaluation of air quality sensor systems - Part 2: Particulate
matter in ambient air
Luftbeschaffenheit - Leistungsbewertung von Luftqualitätssensorsystemen - Teil 2:
Partikelförmige Stoffe in der Außenluft
Qualité de l'air - Évaluation des performances des systèmes capteurs de la qualité de
l'air - Partie 2 : Particules dans l'air ambiant
Ta slovenski standard je istoveten z: CEN/TS 17660-2:2024
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TS 17660-2
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
December 2024
TECHNISCHE SPEZIFIKATION
ICS 13.040.20
English Version
Air quality - Performance evaluation of air quality sensor
systems - Part 2: Particulate matter in ambient air
Qualité de l'air - Évaluation des performances des Luftbeschaffenheit - Leistungsbewertung von
systèmes capteurs de la qualité de l'air - Partie 2 : Luftqualitätssensorsystemen - Teil 2: Partikelförmige
Particules dans l'air ambiant Stoffe in der Außenluft
This Technical Specification (CEN/TS) was approved by CEN on 6 October 2024 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, Türkiye 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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17660-2:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and abbreviations . 10
5 Principle of the evaluation . 13
6 Performance requirements . 17
7 General requirements for the performance of tests . 19
8 Laboratory tests of sensor system . 19
9 Field tests . 21
10 Classification based on the test results . 31
11 Test report . 32
Annex A (informative) Co-location of sensor systems, deployment and management of a
network of sensor systems . 36
A.1 Background . 36
A.2 Co-location and deployment . 36
A.2.1 Individual sensor systems . 36
A.2.2 Sensor networks . 37
A.3 Calibration and validation of networks . 39
Annex B (informative) Evaluation of the effect of electromagnetic fields on the sensor system
measurements . 40
Annex C (informative) Air composition in different outdoor type of sites . 41
Annex D (informative) Selecting the climate for a field trial site . 45
Annex E (normative) Ordinary least square regression formulae . 47
(informative) Values for u bs, RM . 49
( )
Annex F (informative) Example of field tests for the classification process. 52
Annex G (informative) PM testing chamber design for validating coarse particle
measurements . 54
Bibliography. 55
European foreword
This document (CEN/TS 17660-2:2024) 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.
CEN/TS 17660, Air quality — Performance evaluation of air quality sensor systems consists of the following
parts:
— Part 1: Gaseous pollutants in ambient air
— Part 2: Particulate matter in ambient air
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations 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, Türkiye and the
United Kingdom.
Introduction
Sensor systems are generally seen as emerging measuring devices for the monitoring of air quality.
Sensor systems provide a fast and low-cost complement to the reference and equivalent measurement
methods as defined in Directive 2008/50/EC on ambient air quality and cleaner air for Europe [1]. Sensor
systems could allow for air pollution monitoring at a lower cost and with a higher spatial density than
with the reference and equivalent measurement methods. They also allow for new air pollution
applications including monitoring in complex topographies, at traffic junctions, in street canyons, at
remote sites, on mobile platforms (pedestrians, cyclists, vehicles, trams) and for citizen science studies,
e.g. monitoring around areas of local concern, schools, or parks.
Sensor systems use one or more low-cost sensors that are based on several technologies. However,
sensor systems share two common features, portability and low-cost, compared with traditional
reference or equivalent measurement methods. Typically, sensor systems can continuously monitor air
pollution with fast response times ranging from a few tens of seconds to a few minutes.
Currently, the use of sensor systems for air quality monitoring is limited by the low accuracy of
measurements that they can achieve. Additionally, there was no unambiguous protocol for evaluating
sensor systems with a structured metrological approach, ensuring traceability from sensor system
measurements to national and international standards. A protocol will enable exhaustive and transparent
evaluation of sensor systems that can be an important step towards including sensor system
measurements into the monitoring of air quality for regulatory and non-regulatory purposes.
The protocol in this document applies to sensor systems and supports the requirements of Directive
2008/50/EC. This procedure evaluates whether the measurement uncertainty of the sensor system
meets the data quality objectives defined in Directive 2008/50/EC for indicative measurements. This
protocol also allows for a less demanding evaluation of the performance of sensor systems for non-
regulatory measurements.
This document defines common procedures and requirements for the evaluation of the performance of
sensor systems to facilitate mutual recognition by the relevant bodies or stakeholders and thereby
minimise both administrative and cost burdens on manufacturers. It does not describe the roles and
responsibilities of manufacturers, test laboratories and relevant bodies under these procedures.
1 Scope
This document specifies the general principles, including testing procedures and requirements, for the
classification of performance of low-cost sensor systems for the monitoring of particulate matter in
ambient air at fixed sites. The classification of sensor systems includes tests that are performed under
prescribed conditions. It does not guarantee performance in locations that are different from the tests,
variations in meteorological climate from the test programme or account for stability over time, which
can only be assessed under ongoing quality control strategies.
The described procedure is applicable to the determination of the mass concentration of particulate
matter. The pollutants that are considered in this document are PM and PM in the range of
10 2,5
concentrations expected in ambient air.
This document provides a classification that is consistent with the requirements for indicative
measurements and objective estimation defined in Directive 2008/50/EC. In addition, it provides a
classification for applications (non-regulatory measurements) that require more relaxed performance
criteria.
This document applies to sensor systems used as individual systems. It does not apply to sensor systems
as part of a sensor network. However, for some applications (e.g. in cities) sensor systems are deployed
as part of a sensor network. Annex A provides information on the use of sensor systems as nodes in a
sensor network.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 15267-1, Air quality - Assessment of air quality monitoring equipment - Part 1: General principles of
certification
EN 15267-2, Air quality - Assessment of air quality monitoring equipment - Part 2: Initial assessment of the
manufacturer’s quality management system and post certification surveillance for the manufacturing
process
EN 16450, Ambient air — Automated measuring systems for the measurement of the concentration of
particulate matter (PM10; PM2,5)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
ambient air
outdoor air in the troposphere where provisions concerning health and safety at work apply and to which
members of the public do not have regular access
Note 1 to entry: This does not include workplaces as defined by Directive 89/654/EC [2].
[SOURCE: Directive 2008/50/EC] [1]
3.2
averaging period
period of time for which a limit value is associated
Note 1 to entry: For this document, the averaging period is defaulted to 24 h unless otherwise specified (more
information can be found in Directive 2008/50/EC).
3.3
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards and corresponding
indications with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
[SOURCE: JCGM 200:2012, 2.39] [3]
Note 1 to entry: A calibration can be expressed by a statement, calibration function, calibration diagram, calibration
curve, or calibration table. In some cases, it can consist of an additive or multiplicative correction of the indication
with associated measurement uncertainty. Calibration should not be confused with adjustment of a measuring
system, often mistakenly called “self-calibration”, nor with verification of calibration.
Note 2 to entry: This document does not describe the process of calibration of sensor systems.
3.4
Class 1 sensor system
measuring device delivering data that are at minimum consistent with the data quality objectives of
indicative measurements
Note 1 to entry: The term “indicative measurement” does not refer to the performance of the sensor system.
3.5
Class 2 sensor system
measuring device delivering data that are at minimum consistent with the data quality objectives of
objective estimations
Note 1 to entry: The term “objective estimation” does not refer to the performance of the sensor system.
3.6
Class 3 sensor system
measuring device delivering data that comply with a relaxed target measurement uncertainty, but are
not formally associated with any mandatory data quality objective
Note 1 to entry: Relaxed target measurement uncertainties are given in Table 2.
3.7
combined standard measurement uncertainty
standard measurement uncertainty that is obtained using the individual standard measurement
uncertainties associated with the input quantities in a measurement model
[SOURCE: JCGM 200:2012, 2.31] [3]
3.8
coverage factor
number greater than one by which a combined standard measurement uncertainty is multiplied to obtain
an expanded measurement uncertainty
Note 1 to entry: A coverage factor symbol is usually termed k.
[SOURCE: JCGM 200:2012, 2.38] [3]
3.9
drift
continuous or incremental change over time in measurement, due to changes in properties of a sensor
system
Note 1 to entry: Drift is not related either to a change in a quantity being measured or to a change of any recognized
influencing quantity.
3.10
expanded measurement uncertainty
expanded uncertainty
product of a combined standard measurement uncertainty and the coverage factor
Note 1 to entry: The factor depends upon the type of probability distribution of the output quantity in a
measurement model and on the selected coverage probability. The term “factor” in this definition refers to a
coverage factor.
Note 2 to entry: Expanded measurement uncertainty is termed “overall uncertainty” in paragraph 5 of
Recommendation INC-1 (1980) (see the GUM) and simply “uncertainty” in IEC documents.
Note 3 to entry: Expanded measurement uncertainty is also referred to as “uncertainty” in this document.
[SOURCE: JCGM 200:2012, 2.35] [3]
3.11
equivalent method
method for the measurement of the concentration of particulate matter (PM ; PM ) meeting the data
10 2,5
quality objectives for fixed measurements and tested according to EN 16450
3.12
exposure chamber
test chamber
volume that can be sealed with controlled conditions of temperature, humidity and test aerosol, used for
testing the sensor system
3.13
fixed measurements
measurements taken at fixed sites, either continuously or by random sampling, to determine the levels
in accordance with the relevant data quality objectives
Note 1 to entry: The data quality objectives are listed in Table 2 (more information can be found in Directive
2008/50/EC).
3.14
independent measurement
measurement that is not influenced by a previous individual measurement, by separating two individual
measurements by at least four response times
3.15
indicative measurements
measurements which meet data quality objectives that are less strict than those required for fixed
measurements
Note 1 to entry: The data quality objectives are listed in Table 2 (more information can be found in Directive
2008/50/EC).
3.16
PM
10-2,5
difference between reported PM and reported PM concentrations, also termed coarse particles
10 2,5
3.17
PM
x
particulate matter suspended in air which passes through a size-selective inlet at a constant flow with a
50 % efficiency cut-off at x µm aerodynamic diameter
Note 1 to entry: By convention, the size-selective standard inlet designs prescribed in EN 12341 — used at the
prescribed flow rates – possess the required characteristics to sample the relevant PM fraction suspended in
ambient air.
Note 2 to entry: The efficiency of the size selectiveness of other inlets used could have a significant effect on the
fraction of PM surrounding the cut-off, and, consequently on the mass concentration of PMx determined.
[SOURCE: EN 12341:2023] [4]
3.18
measurement repeatability
repeatability
measurement precision under a set of repeatability conditions of measurement
[SOURCE: JCGM 200:2012, 2.21] [3]
3.19
objective estimation
measurements which meet data quality objectives that are less strict than those required for indicative
measurements
Note 1 to entry: The data quality objectives are listed in Table 2 (more information can be found in Directive
2008/50/EC).
3.20
reference method
standard gravimetric measurement method for the determination of the PM or PM mass
10 2,5
concentration of particulate matter according to EN 12341 [4]
3.21
repeatability condition of measurement
conditions that include the same measurement procedure, same operators, same measuring system,
same operating conditions and same location, and replicate measurements on the same or similar objects
over a short period of time
Note 1 to entry: A condition of measurement is a repeatability condition only with respect to a specified set of
repeatability conditions.
Note 2 to entry: In chemistry, the term “intra-serial precision condition of measurement” is sometimes used to
designate this concept.
[SOURCE: JCGM 200:2012, 2.20] [3]
3.22
sensor
individual sensor
physical unit that produces a signal related to the concentration of particulate matter in air
3.23
sensor system
single integrated set of hardware that uses one or more sensors to produce a signal related to the
concentration of particulate matter in air that can supply real time measurements
Note 1 to entry: The term “instrument” has a very similar definition, but many researchers are typically referring
to a reference or equivalent grade device when using the word “instrument”.
Note 2 to entry: All the tests that are intended in this document are designed for sensor systems only.
Note 3 to entry: Sensor systems contain many common components in addition to the basic sensing or analytical
element that is used for detection. Common core components and functions can include:
— sensing detector (the actual sensor);
— sampling capability (generally active sampling for PM);
— power systems, which may include batteries;
— analogue to digital conversion;
— signal processing;
— local data storage;
— data transmission;
— enclosure.
3.24
standard measurement uncertainty
standard uncertainty
measurement uncertainty expressed as a standard deviation
[SOURCE: JCGM 200:2012, 2.30] [3]
3.25
uncertainty of measurement
measurement uncertainty
non-negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
Note 1 to entry: Measurement uncertainty includes components arising from systematic effects, such as
components associated with corrections and the assigned quantity values of measurement standards, as well as the
definitional uncertainty. Sometimes estimated systematic effects are not corrected for, but instead, associated
measurement uncertainty components are incorporated.
Note 2 to entry: The parameter may be, for example, a standard deviation called standard measurement
uncertainty (or a specified multiple of it), or the half-width of an interval, having a stated coverage probability.
Note 3 to entry: Measurement uncertainty comprises, in general, many components. Some of these may be
evaluated by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity values
from series of measurements and can be characterized by standard deviations. The other components, which may
be evaluated by Type B evaluation of measurement uncertainty, can also be characterized by standard deviations,
evaluated from probability density functions based on experience or other information.
Note 4 to entry: In general, for a given set of information, it is understood that the measurement uncertainty is
associated with a stated quantity value attributed to the measurand. A modification of this value results in a
modification of the associated uncertainty.
[SOURCE: JCGM 200:2012, 2.26] [3]
4 Symbols and abbreviations
4.1 Symbols
For the purposes of this document, the following symbols apply.
NOTE In the following list, all symbols related to the measurement uncertainty of source contributions are
indicated as standard uncertainty, e.g. . However, in the text expanded uncertainties of the same source
uX
( )
contributions can be used, e.g. .
UX
( )
a
intercept of the regression line
slope of the regression line
b
c
intercept of the corrected dataset
d slope of the corrected dataset
FINE
F
factor of the sensor response change from fine to coarse conditions
COARSE
k coverage factor
L LV, UAT or LAT currently being assessed
median of Sensorratio with hourly RH% between 30 % and 60 %;
Mdn sensorratio
( )
30−60%
median of Sensorratio with hourly RH% between 85 % and 95 %.
Mdn sensorratio
( )
85−95%
n
is the number of measurement periods where all sensor systems are
providing valid data (with identical n )
s
number of replicate sensor systems
n
s
PM coarse, difference between reported PM and reported PM
10 2,5
PM
10−2.5
concentrations
r
measurement repeatability; repeatability
value of the residual sum of squares resulting from the linear regression
R
coefficient of determination
R
factor that expresses the change in sensor response (compared to the
RH
factor
equivalent method) when RH changes from low (30 % - 60 %) to high (85 %
to 95 %)
PM (sen, FINE) PM sensor response (µg/m ), averaged over the duration of the test with
2,5 2,5
fine PM fraction
PM (eq, FINE) PM measured by equivalent method (µg/m ), averaged over the duration
2,5 2,5
of the test with fine PM fraction
PM (sen, COARSE) PM sensor response (µg/m ), averaged over the duration of the test
10-2,5 10-2,5
with coarse PM fraction
PM (eq, COARSE) PM measured by equivalent method (µg/m ), averaged over the
10-2,5 10-2,5
duration of the test with coarse PM fraction
ratio of sensor to reference method measurements for PM during the test
2,5
R
PM FINE
( )
2,5
with fine PM fraction
ratio of sensor to reference method measurements for PM during the
10-2,5
R
PM COARSE
( )
10−2,5
test the test with coarse PM fraction
ratio of hourly average of the sensor PM measurement to the hourly average
Sensor ratio
of the PM measurements of the equivalent method for PM or PM
2,5 10
hourly average of sensor measurement
y
sen
hourly average of equivalent method
y
eq
standard uncertainty of the intercept of a regression line
ua
( )
standard uncertainty of the slope of a regression line
ub
( )
between reference method standard uncertainty
u bs,RM
( )
between sensor systems standard uncertainty
u bs,s
( )
expanded uncertainty of the field measurements of the sensor system at the
U
field,L
value of ‘L =’ LV, UAT or LAT currently being assessed, in units of mass
concentrations
expanded uncertainty of the corrected sensor system at the value of ‘L =’ LV,
U
field,corr,L
UAT or LAT currently being assessed, in units of mass concentrations
x
value of the reference measurement
th
i x-value (reference measurement)
x
i
average of the values x
x
i
y
value of the sensor system response
th
i y-value (sensor system response)
y
i
value of the sensor system response for period i of sensor system j
y
i,j
y
average of the values y
i
y average for period i of the n replicate sensor systems;
i s
4.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
AQMS air quality monitoring station (more information on the measurement methods can
be found in Directive 2008/50/EC)
DQO data quality objective
GPS global positioning system
LAT lower assessment threshold
LV limit value
OLS ordinary least squares
R coefficient of determination
RH relative humidity
RSS residual sum of squares resulting from the linear regression
SOP standard operating procedure
UAT upper assessment threshold
WLAN wireless local area network
5 Principle of the evaluation
5.1 Introduction to the methodology
The scheme in Figure 1 shows the focus and activities that are part (performance evaluation) and not
part (preparation, deployment) of the test procedure specified in this document.
This document expects sensor systems to deliver measurements directly as PM and PM
10 2,5
concentrations expressed as mass per unit volume without the need for calibration as part of this test
procedure.
If calibration is part of the normal operating procedure, then data collected during the performance
evaluation cannot be used to calibrate an individual sensor system. Calibration shall be done in the
preparation phase before providing the sensor systems for performance evaluation (first box in Figure 1).
Data from the performance evaluation (second box in Figure 1) cannot be used for this initial calibration
of individual sensor systems. Calibration during preparation (first rectangle in Figure 1) shall be done at
a location different than the location(s) of the performance evaluation (second box in Figure 1) unless
calibration at each deployment site is part of the standard operating procedure (SOP) defined by the
manufacturer. If the standard operating procedure (SOP) defined by the manufacturer includes a
calibration periodicity which is within the time frame of the evaluation, then calibration is performed
without using the evaluation dataset. The performed calibration during evaluation phase (if part of the
SOP) is reported in the test report and implies that this periodicity of calibration is mandatory during
deployment of the sensor system as a Class 1, Class 2 or Class 3 sensor system.
The performance evaluation can result in a unique linear correction function (see 9.7.3) that can be
applied to the full dataset and all sensor systems; It is imperative that any applied slope and/or intercept
correction shall be universal for all datasets (i.e. all individual sensor systems at all individual AQMS).
During the deployment phase, a sensor system can be used according to its classification for indicative
measurements or objective estimations (more information can be found in Directive 2008/50/EC). The
manufacturer’s deployment and preparation procedures shall be followed, and the SOP used during the
performance evaluation shall also be applied during deployment to be valid as a Class 1, Class 2 or Class 3
sensor system. The manufacturer shall specify regular QA/QC procedures that shall be applied during
deployment to ensure performance and long-term stability.
Figure 1 — Scheme of activities that are part of this document (performance evaluation) and not
part of this document (preparation, deployment)
5.2 General objective
This document describes the test protocol and data quality objectives (DQOs) for the evaluation and
classification of sensor systems. This document focuses on evaluation of the PM sensors in the sensor
systems. The aim of the protocol is to have a standardised approach for sensor system testing and
classification. The protocol requires the execution of both laboratory tests and field tests at air quality
monitoring stations (AQMS) where sensor systems and reference and equivalent measurement methods
are co-located and compared. The sensor system measurements are compared to measurements using
the reference method for the evaluation of the DQOs and are also compared to data of equivalent
measurement methods for evaluation of other requirements (relative humidity (RH), PM ) and for
10-2,5
reporting the measurement uncertainty. The results of the field tests are only representative of the
selected type of station location, climate and season. Results are likely to be different at other field sites
where different air composition and climate can result in different sensor performance.
Three classes are specified in this document:
— Class 1 and Class 2 sensor systems for regulatory or other purposes that fulfil the DQOs for
respectively indicative measurements and objective estimation;
— Class 3 sensor systems for non-regulatory purposes that have relaxed target measurement
uncertainty requirements, e.g. for specific research topics, educational purposes and citizen science.
NOTE More information on indicative measurements and objective estimation can be found in Directive
2008/50/EC.
Classification of sensor systems is valid for sites that fulfil the site classification and meteorological
conditions specified in the accompanying classification report (see Clause 11).
5.3 Protocol
The test procedure includes both laboratory test and field tests. The test procedure will result in a
classification and reporting of the test results. If the performance requirements of the laboratory test are
not met, a sensor system cannot be classified as Class 1 irrespective of the results of the field tests.
Performance requirements are listed in 6.2. Data treatment of the results of field tests can be performed
either without correction of the response of sensor systems or correcting the field trial data with a single
universal slope and/or intercept correction for all sensor systems at all test sites. These correction
methods are detailed in 9.7.
5.4 Initial requirements
Before starting the laboratory pre-tests, the following characteristics and parameter shall be understood
and agreed:
— size fraction of interest and the corresponding limit value (LV), only for Class 1 and Class 2 sensor
systems (see Table 2);
— type of monitoring sites where sensor systems will be deployed (urban, suburban or rural areas at
background or traffic sites) (see 9.2).
In this document sensor systems are expected to deliver measurements directly in mass concentration
units without the need for calibration before tests, unless this is part of the SOP to use the sensor systems
under test (see 5.1). This document is not intended to provide guidelines for developing a calibration or
correction model of sensor system measurements.
5.5 Test infrastructure
An independent competent body shall perform the testing. The classification shall be awarded by or on
behalf of the competent authority. The competent body performing the required tests shall be able to
demonstrate that it conforms with the requirements of internationally accepted standards for test
laboratories.
NOTE 1 EN ISO/IEC 17025 [5] is the harmonized internationally accepted standard that applies.
NOTE 2 A formal accreditation by a member body of the European Accreditation Organisation to
EN ISO/IEC 17025 is a demonstration of conformity.
5.6 Test results and classification
Classification is based on the performance requirements of the laboratory tests (Clause 8) and the field
tests (Clause 9).
To be awarded Class 1, Class 2, or Class 3, each sensor system shall individually also meet the
performance requirements of the laboratory, and DQOs and performance requirements of the field tests
(see Table 2 and Table 3).
Final classification is discussed in more detail in Clause 10.
5.7 Sensor system design changes
To identify changes in firmware and software, the sensor systems shall make the version numbers
available to the user within the configuration and data retrieval protocols. The firmware and software
version numbers of the sensor systems used for type testing shall also be recorded in the test report.
The version number of the sensor system manual supplied during type testing shall be recorded in the
test report.
The manufacturer shall follow the requirements of EN 15267-1 and EN 15267-2 when making software,
firmware and/or hardware design changes to type-tested sensor systems.
5.8 List of tests to be performed
The list of required laboratory and field tests are listed below. Clause 7 defines the general requirements
on test performance. Clause 8 and Clause 9 give details of the laboratory and field trial tests respectively.
Tests to be performed for the evaluation of sensor systems in the laboratory or at field sites:
a) Step 1:
1) coarse particle test (8.1);
2) optional laboratory test (8.2; e.g. electromagnetic field effects; see Annex B).
b) Step 2:
1) field test (Clause 9).
Table 1 summarizes the test conditions and method of validation for the laboratory test and field tests.
Table 1 — Test conditions and procedures of laboratory and field tests
Laboratory test (Clause 8) Sensor systems are exposed to coarse and fine dust in an
exposure chamber to evaluate their response to PM . The size
10-2,5
fractions are given in 8.1
An equivalent method (as defined in 8.1) is used to measure PM
2,5
and PM and calculate PM
10 10-2,5
Field tests (Clause 9) Number of sites: see 9.2;
Duration: see 9.2;
The exact time period shall respect the data requirement given in
9.2
Sensor systems are co-located with reference and equivalent
methods at all locations
Reference method is used for classification (DQO) and to evaluate
requirements for between sensor uncertainty and PM
10-2,5
Equivalent method is co-located to evaluate restrictions related
to impact of RH and to estimate measurement uncertainty of
hourly averages.
6 Performance requirements
6.1 Data Quality Objectives (DQOs)
The DQOs are listed in Table 2. They are established using the DQOs of indicative measurements and
objective estimations for Class 1 and Class 2, respectively (more information can be found in Directive
2008/50/EC). DQOs are calculated for different levels including the limit value (LV), upper assessment
threshold (UAT) and lower assessment threshold (LAT).
Only the DQOs at LV (using reference method, 24 h) are used for classification (see Clause 10). The
expanded measurement uncertainty at LAT and UAT shall also be calculated and reported in the test
report to show if sufficient data quality is obtained at lower concentrations when these sensor systems
are used as indicative measurements or objective estimations. DQOs using hourly values shall also be
reported but are not used to determine the classification.
Table 2 — Data Quality Objectives specified as maximum expanded uncertainties
Pollutant Averaging LV UAT LAT DQO of DQO of DQO of
period Class 1 Class 2 Class 3
sensor sensor sensor
system system system
3 3 3 3 3 3
h µg/m µg/m µg/m µg/m µg/m µg/m
(% of LV) (% of LV) (% of LV)
PM 24 50 35 25 25 50 100
(50 %) (100 %) (200 %)
a
PM 24 30 21 15 15 30 60
2,5
(50 %) (100 %) (200 %)
a 3
For PM a concentration of 30 ug/m shall be used as a substitute value for the daily limit value.
2,5
NOTE 1 Table 2 presents LV’s and other thresholds that are set in Directive 2008/50/EC (and with respect to
PM2,5 EN 12341).
NOTE 2 The values within brackets in the DQO columns represent the percentage of the corresponding LV.
6.2 Performance requirements per test
The sensor system under evaluation shall meet all the performance requirements specified in the tests
defined in Table 3 and DQOs (as maximum expanded measurement uncertainty) as defined in Table 2.
Performance criteria are based on daily PM measurements of the reference method (24 h) unless
otherwise indicated with an asterisk (*).
For the evaluation of the field data the evaluation is done for the following parameters and datasets:
— between sensor systems standard uncertainty, u(bs,s), per test site;
— minimum data capture, per test site, per sensor system;
— slope and intercept of regression line, per test site, per sensor system;
— slope and coefficient of determination, R , of the regression line of sensor versus reference PM
10-2,5
for the test results of all test sites combined, per sensor system;
— RH factor, per test site, per sensor system.
Table 3 — Sensor system performance requirements per type of test
Parameter
Evaluated Class 1 Class 2 Class 3
(see Clause 8 or 9
compound sensor systems sensor systems sensor systems
for more details)
Laboratory Coarse fraction PM
FINE
F < 2
COARSE
3 3 3
Between sensor PM and
Field 10 u(bs,s) ≤ 3 µg/m u(bs,s) ≤ 5 µg/m u(bs,s) ≤ 7 µg/m
system standard PM
2,5
uncertainty
Data capture of Data capture of 24 h
Minimum data PM and
c c
24 h averages shall averages shall be at –
capture PM2,5
be at least 90 % least 50 %
PM10 and
a
RH < 1,5 1,5 < RH < 2,5
RH
factor factor
PM2,5
0,5 < slope <2
PM PM
10-2,5 10
R > 0,5
Coarse fraction
No pattern
identified
Slope of regression PM10 and
0,78 ≤ b ≤ 1,29 0,60 ≤ b ≤ 1,67 0,43 ≤ b ≤ 2,33
b
line PM
2,5
3 3 3
–3 µg/m ≤ a –5 µg/m ≤ a –7 µg/m ≤ a
Intercept of PM10 and
b
3 3 3
regression line PM2,5
≤ 3 µg/m ≤ 5 µg/m ≤ 7 µg/m
a
Evaluation is based on equivalent measurement method (1h).
b
Evaluation for hourly values will only be reported.
c
24 h average data are only valid when:
- there are at least 90 % of the hourly averages within 24 h for Class 1 sensor systems;
- there are at least 50 % of the hourly averages within 24 h for Class 2 sensor systems.
7 General requirements for the performance of tests
7.1 Number of sensor systems
Three complete and identical sensor systems (same model, hardware, firmware and software
configuration and version) under evaluation shall be tested per site and season. Additional optional
sensors systems are considered as spare sensor systems and are labelled as such. The spare sensor
systems are installed from the start of the test and the data from these sensor systems are only used when
required (see 9.7.2).
The supplied sensor systems shall be selected by the manufacturer and shall be representative of the
current production variability.
7.2 Preparation of the sensor systems prior to the tests
The sensor systems shall be prepared and mounted (during field tests) in a manner representative of the
typical application, in accordance with the instruction manual, including all necessary interconnections,
initial adjustments and initial calibrations.
For all tests, it is mandatory to respect the setup procedure (installation, communication) of sensor
systems prescribed by the manufacturer.
Laboratory and multiple location field tests of sensor systems may be carried out in parallel to expedite
validation.
8 Laboratory tests of sensor system
8.1 PM10-2,5 test
To test whether a sensor system can measure both the fine and coarse PM fractions, it is necessary to
perform a laboratory test using monodisperse or polydisperse particles with certain size restrictions.
Whereas classification of PM sensor systems for PM is based on field tests, this laboratory test is
2,5
introduced to determine if a sensor system under evaluation for PM can correctly measure the coarse
fraction. Most European monitoring/testing sites offer field sites where PM10 concentrations are close to
PM concentrations. Laboratory PM testing using a test chamber (see Annex H) can generate conditions
2,5
where sensor systems can be exposed to either mostly fine PM or mostly coarse PM. To pass the
laboratory coarse test, sensor systems shall show a similar relative response as the equivalent method
when sampling separately both fine and coarse PM fractions.
NOTE For the laboratory test, the configuration of the equiv
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