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CEN Draft Technical Report
‘Guide for the use of direct-reading
instruments for aerosol monitoring’
Member of CEN/TC137/WG3
AnAn Agency of the Health and Safety
Agency of the Health and Safety Executive   Executive
CEN/TC137/WG3
•       European standards committee:
‘Assessment of Workplace Exposure – Particulate Matter’.
•       Produces standards and technical reports (guidelines)
on measurement of exposure to aerosols in the
•       Currently working on standards for:
– Revision of EN 13205: Assessment of performance of instruments for
measurement of airborne particle concentrations
– prEN ISO 28439: Characterisation of ultrafine aerosols/nanoaerosols –
Determining the size distribution and number concentrations using differential
electrical mobility analysing systems
– Revision of EN 15051: Measurement of the dustiness of bulk materials –
– CEN/TR: Guide for the use of direct-reading instruments for aerosol
CEN/TC137/WG3 (cont’d)
•       Strong liaison with:
– ISO/TC146/SC2/WG1, Air Quality/Workplace Atmospheres -
Particle Size-selective Sampling and Analysis (hold joint
meetings – David Bartley ex-NIOSH, convenor)
– ISO/TC44/SC9/WG2, Health and Safety in Welding and Allied
Processes – Sampling of airborne particles and gases in the
operator’s breathing zone
– ISO/TC229, Nanotechnology – WG2: Measurement and
Characterisation, WG3: Health, Safety and Environment
CEN/TRxxxx: Guide for the use of direct
reading instruments for aerosol monitoring
Currently has three parts:
Part 1: Choice of monitor for specific applications
Draft 5 – I will present here
Part 2: Evaluating airborne particle concentrations using Optical
Draft 4 – Peter G&#246;rner will present here
Part 3: Evaluating airborne particle concentrations using
Part 4: Evaluating airborne particle concentrations using other
May not be started – depends on availability and use of
suitable instruments (TEOM, piezobalance, β attenuation,
Part 1: Choice of monitor for
2.            Scope and area of application
3.            References
4.            Principles of direct-reading aerosol monitoring methods
–             Introduction
–             Vibrational mass methods
•        Piezoelectric mass monitors
•        TEOM - Tapered Element Oscillating Microbalance
–             Beta mass monitors
–             Optical measurement of aerosols
•        Photometers
•        Optical particle counters
5.            Requirements for different applications of direct-reading dust
6.            Bibliography
2. Scope and area of application
•       Aim of Part 1 of TR is to produce simple, easy-to-read document
to enable non-specialists to choose most appropriate monitor for
•       The principles underlying the evaluation of one or more aerosol
fractions using direct-reading aerosol monitors are given
•       Involves only currently available methods for monitoring levels of
aerosols in workplaces for a range of different purposes
•       Details of their limits and possibilities in the field of occupational
hygiene are given
•       Does not cover the sampling of aerosols for compliance with
occupational exposure limits or the collection of aerosol particles
•       Does not include instruments for ultrafine and nanoparticles (they
will have separate documents)
4. Principles of direct-reading
aerosol monitoring methods
•       Automatic methods are classified into three
– Vibrational mass monitors
– Beta attenuation monitors
– Optical monitors
•       Methods in first two groups involve sampling
and collection of particles on substrates for
analysis of mass by on-board techniques
•       Optical monitors are the most numerous
because of their high sensitivity and ease of
Information given for each group
• For each group of monitors, the following
– Determination of mass concentration of health-
– Calibration of monitor
– Currently available monitors (not comprehensive)
Example: Piezoelectric mass
Piezoelectric crystal                              Particles
•   Operating principle
– Particles drawn into the instrument
Filter                         are collected the surface of a
f               piezoelectric crystal, forming part of
a quartz crystal-based oscillating
– The mass of deposited particles
+                                        causes a reduction in the oscillation
Schematic of piezoelectric
– Frequency reduction is directly
proportional to the particle mass
Δf = reduction in frequency
Δf                                              Q = sampling flowrate
Aerosol concentration, C =
Qtk f                                            t = sampling time
kf = proportionality constant
Determination of mass concentration
of health-related fractions
• Change in frequency Δf mass of particles deposited
and largely independent of the physical and chemical
properties of the particles
•       No need therefore to use on site calibration factors,
providing that the crystal is not overloaded
•       Only respirable fraction is measurable, because of
particle size limitations on particle/sensor coupling
•       Respirable size selection can be achieved using any
suitable size selector; one instrument uses a single
stage impactor with the respirable particles deposited
on the crystal by electrostatic precipitation.
Calibration of piezoelectric instruments
•       Each crystal sensor has its own frequency
response and so the instrument incorporating
the crystal will be calibrated in the factory to
give the required mass response.
•       Provided that the crystal is not damaged, no
Advantages                                           Disadvantages
Usage limited by dust loading on
Direct measurement of dust mass
No on-site calibration required             Regular cleaning of crystal required
Response independent of chemical
Only suitable for respirable particles
composition and particle size (below
Moisture can condense onto
Relatively easy to use                      deposited particles and effect mass
Currently available piezobalance
instruments (manufacturer’s information)
Portable/            Size (mm)     Size          Flowrate
Name                                                                             Response time    Accuracy    range
personal             /weight       selection     (l min-1)
Kanomax                                                                          0 – 1 mg m-3:
Piezobalance                             311x170x130                             24 s             &#177; 10 % of
Portable                           fraction by       1                                    0.02 – 10
dust monitor                             2 kg                                    1 – 10 mg m-3:   reading
Model 3511                                                                       120 s
NOTE: “Accuracy” is defined by the manufacturers
Advantages                                         Disadvantages
Very fast response                          Response not directly proportional to
mass, but is dependent upon particle
size, shape and refractive index
Very wide concentration range               Need factory and on-site calibration
for mixed or varying aerosols
Portable and personal models                Response drops off for particles &gt; 10
available                                   μm, so only suitable for respirable
Passive models require very little          Oversensitive to fine aerosols (e.g.
power                                       water mist, fume and cigarette
Pumped models may have filter
collection that can be used for
Very simple use (most simple of all
types of monitor described)
Currently available photometers (not
comprehensive, manufacturers information)
Personal   Size (mm)       Particle size    Measurement
(flowrate                                                                 Precision                                                                           Display and data
Instrument name                      or      and weight         range            range                        Accuracy         Resolution                 Calibration
l min-1),                                                                (mg m )
portable      (kg)             (μm)           (mg m-3)
Factory calibrated to ISO
245x95x50                                                                                                                            128x64 pixel screen
12103-1 using A2 fine test
Casella Microdust                               Probe                                                                                      -3                                      gives rolling averages of
Passive       Portable                        NM             0 - 2500         NM             NM           0.001 mg m         dust and can be calibrated
Pro                                            290x35&#248;                                                                                                                             concentration, 15,700
on-site using add-on
1.0                                                                                                                               points data logger
229 x 70 x 63                                                    &#177; 10% to                           Factory calibrated to NIOSH       1 line LCD, Optional
SKC Haz-dust 1      Passive       Portable                      0.1 - 50        0.01 - 200       &#177; 0.02                             NM
0.5                                                       NIOSH 0600                           0600 with SAE fine dust           data logger
Factory calibrated to NIOSH
0.1 – 10 (R)                                                                        0600 with ARD. Has
Pumped (2)               180 x 80 x 45                                                    &#177; 10% to                                                             4 line LCD, 21,500
SKC Split2                        Personal                   0.1 – 50 (T)*     0.01 – 200        &#177; 0.02                             NM           inhalable entry and back up
or passive                    0.8                                                       NIOSH 0600                                                             points data logger
0.1 – 100 (I)*                                                                      filter as standard and
calibration post for on site
-3    Factory calibrated to
Pumped                    130x92x70      impactors to                                                     0.001 mg m                                           2 line LCD, 31,000
TSI Sidepak                       Personal                                     0.001 – 20         NM             NM                              respirable fraction of ISO
(0.7 - 1.8)                  0.5            choose                                                            (min)                                            points data logger
12103-1 with A1 test dust
“none”, 1.0,
Pumped                   221x150x87        0.1 – 10                                                                          Factory calibrated to ISO         1 line LCD, 31,000
TSI Dustrak                       Portable                                     0.001 – 100        NM             NM             reading or
(1.4 - 2.4)                  1.5           (approx)                                                                    -3    12103-1 with A1 test dust         points data logger
0.001 mg m
&#177; 2% of           0.1% of         Factory calibrated with SAE
Thermo DataRAM      Pumped (1                134x184x346                                                                                                                           8 line LCD, 50,000
Portable                     0.08 - 10      0.0001 – 400       &#177; 0.01       reading &#177;         reading or       fine test dust and has in-built
4                   to 3                         5.3                                                                                        -3                                     points data logger
precision       0.0001 mg m        optical scattering element
pumped (1                                                                                                                    Factory calibrated with SAE
&#177; 5% of           0.1% of
Thermo personal     – 5) with                 153x92x63      0.1 – 10 ( max                                                                      fine test dust and can be         2 line LCD, 13,000
Personal                                     0.001 – 400      &#177; 0.005       reading &#177;        reading or
DataRAM             add-on                   0.5 (passive)     response)                                                                         calibrated on-site using add-     points data logger
precision       0.001 mg m-3
pump/filter                                                                                                                  on pump/filter system
100x36x95
&#177; 10% to
0.3                                                                                        -3    Factory calibrated with 0.6       1 line LCD, 60,000
Sibata PDS 2        Pumped (2)    Personal                        NM           0.001 - 100        NM          Calibrated      0.001 mg m
Control unit                                                                                        μm latex spheres                  points data logger
98x43x106
Factory calibrated with
200x110x40                                                                                                                            4 digit display in mass
Hund TM-&#181;P          Passive       Portable                    Respirable         0 - 100       0.01 (LOD)        NM                              respirable coal dust –can be
1.0                                                                                                                               concentration
calibrated with other dusts
110x63x69           Three                                          ?30%
0-250 for each
Pumped (3                    0.48         fractions via                                 following EN
TSI Respicon                      Personal                                       of the 3      0.05 (LOD)                         0.01 %
– 11)                    Datalogger           virtual                                       13205
210x100x55         impactors                                    procedures
NOTE: “Precision”, “accuracy” and “resolution” are defined by the manufacturers themselves and may be different
NM = Not Safety Executive
An Agency of the Health andmentioned
5. Requirements for different applications
of direct-reading aerosol monitors
•       Presented here are the requirements that a suitable direct
reading aerosol monitor must have for different applications.
•       The reader can then compare these requirements with the
characteristics of the available instruments given in Section 4 to
enable the most suitable choice of direct reading aerosol monitor
to be made for his/her specific application.
•       Six different potential uses of direct reading aerosol monitors are
–     Walk through surveys
–     Identification of main process or source emitting aerosols
–     Use with video visual techniques
–     Assessing efficiency of control systems
–     Watchdogs to monitor levels in workplaces and ensure controls are working
–     Surrogate personal exposure assessment
Example 1 : Walk through surveys
•       For walk through surveys, the direct-reading aerosol
monitor should have the following attributes:
– Portable (battery-powered)
– Response preferably independent of particle characteristics
(particle size and composition)
– Concentration displayed on an in-built screen
– Particle size selection not important
•       Walk through surveys could provide additional
information for inclusion in the Basic Survey outlined in
EN 689 (1995) –Sampling strategy document
Example 2: Watchdogs to ensure
•       For use as watchdogs to monitor levels in workplaces
to ensure that deployed controls are working, the
direct-reading aerosol monitor should have the
– Simple, cheap (passive) monitors for multiple use around
– Can be battery or mains powered
– Response calibrated against reference monitors, possibly
personal monitors for specific processes, so response does
not have to be independent of particle characteristics
– Information tele-metered to central hub system
– Alarm function set to go off when agreed level exceeded
– Fast response not necessary
Example 3: Surrogate personal
• Direct reading aerosol monitors cannot currently be
used to measure exposure to determine compliance
with occupational exposure limits (OELs).
•       However, there are a number of situations where an
indication of exposure is important:
– a) use with video visual techniques to demonstrate changes in
techniques to minimise exposure for worker training,
– b) for situations where there is no OEL and relative changes in
exposure as measured with direct reading aerosol monitors can be
used to demonstrate improvements in control.
•       For this purpose, the direct reading aerosol monitor
exposure assessment - attributes
•       Personal and unobtrusive
•       Particle size selectivity related to the potential health
effects from the process being monitored
•       Response calibrated on-site against in-built filter or
suitable compliance sampler worn alongside direct
reading aerosol monitor
•       Fast response time for video visual work, but not
necessary for demonstrating overall reduction in
Progress with guidance documents
•      Currently Parts 1 and 2 have been accepted
as new work items by CEN/TC 137
•      Both have been under discussion for about 2
years, but still not final versions
•      Any comments you may have will be very
•      TIMELINE:
1 March 2009:                       Circulation of first draft
1 September 2009:                   Dispatch of draft for Technical