2014 Conference on Monitoring and Surveillance of #Asbestos-Related Diseases. Dimensional criteria of fibers counted in industrial hygiene have been defined by WHO as the fibers having a length greater than 5 microns, a diameter less than 3 microns and a ratio length/diameter greater than 3. But the PCM technique is limited and can only count fibers whose diameter is between 3 and 0.2 micrometers. But the asbestos fibers may have a diameter of 0.02 microns (20 nanometers) for the finest of them. With ATEM, it is possible firstly to observe thinner and smaller fibers and, above all, to differentiate asbestos fibers from other mineral fibers (by chemical analysis and electron diffraction techniques).

1. Asbestos exposure measurement investigation using
Analytical Transmission Electron Microscopy (ATEM)
A.Romero-Hariot, F.Clerc, C.Eypert-Blaison, M.Guimon, R.Vincent
Espoo, FINLAND - 13 February 2014
Our job: making yours safer

2. Size criteria for fibers defined by World Health Organization (WHO) in 60s
Schematic representation of the size distribution of asbestos fibers in the
air (fibers L/D >3)
Thin fibers (TAFs)
not visible by PCM but visible
by ATEM
L > 5 µm
0.02 µm < D < 0.2 µm
Length > 5 µm
Diameter < 3 µm
L/D > 3
Background
WHO fibers
visible by PCM
L >5 µm
0.2 µm < D < 3 µm
Short fibers (SAFs)
not counted in
occupational environment and
ambiant air
L< 5 µm
D < 3 µm

3. Background
 February 2009 :
 The French Agency for Environmental and
Occupational Health Protection (AFSSET – now
ANSES) published a report on the toxicity of short
asbestos fibers (SAFs) and thin asbestos fibers
(TAFs)
> The carcinogenic nature of TAFs has been confirmed
> The toxicity of SAFs has not been excluded
3
 September 2009:
 AFSSET published recommendations for lowering the
concentration of airborne asbestos fibers in workplaces
> By using Analytical Transmission Electron Microscopy (ATEM), in
order to include the thinnest fibers (less than 0.2 µm in diameter)
not visible by phase-contrast microcospy (PCM)
> By reducing, as an initial step, the occupational exposure limit
value (OEL) by a factor 10, i.e. an 8-hour OEL of 10 fibers per litre
(f.L-1)
http://www.anses.fr/en/content/short-
asbestos-fibers

4. Background
 November 2009:
 The French Directorate-General for
Labour (DGT) launched an asbestos
exposure measurement investigation
using ATEM
> To establish a method and validate the
feasibility of sampling airborne asbestos
fibers in the occupational environment with
an ATEM analysis
> To ascertain the dust level generated by
the various “Asbestos containing
material (ACMs) – Technical process”
combinations when measured by ATEM,
in order to implement technical rules
minimizing the release of dust into the air
and determine protective measures
adapted to these levels
> To establish the particle size distribution of
the different classes of fibers on the
sampling filters
4
Summary (English) & report (French) are
available on INRS English website
http://en.inrs.fr/ accessible from www.inrs.fr

5. Sampling procedure
 Protocol
 This investigation was conducted
> On worksites in actual work situations, covering the removal, indoors and outdoors, of friable and
non friable ACMs, as well as maintenance conducted on these materials
> On 25 processes (i.e. “ACMs / removal technique” combinations), with 5 different worksites for each
process
 The sampling strategy consisted in
> Collecting two 2-hour personal samples, twice per day
> 500 results expected: 25 processes X 5 worksite X 4 samplings
> Sampling flow rate: 3 liters per minute
 A labor inspector officer checked for compliance
with the sampling protocol at the worksite
 Preparation of filters
 Depending on the level of dust, for one sampling
> Two filters were processed together (very low dust),
> ½ of each filter was processed together (low dust)
> ¼ of each filter was processed together (strong dust)
> 1/8 of each filter was processed together (very strong dust)
> Acidification if required because of mineral particles
5
© A.Romero-Hariot / INRS

6. The campaign
 A few illustrations of worksite types
6
Dismantling of a suspended ceiling Removal of sprayed asbestos by scraping with
a spatula
Dismantling of a roof with asbestos containing
cement
Removal of asbestos containing black glue by
grinding / sanding
Removal of asbestos containing road surfaces
by planing
Removal of asbestos containing cement pipes
by manual tube cutting
© A.Romero-Hariot / INRS© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS© A.Romero-Hariot / INRS

7. ATEM Measurements
 Preparation method and counting
 NF X 43-050, 1996: “Air quality: Determination of the concentration of
asbestos fibers using transmission electron microscopy – Indirect
method”
 Fibers complying with the following are counted:
> The WHO size criteria visible by PCM, i.e. :
• 0.2 µm < fiber diameter (D) < 3 µm
• fiber length (L) > 5 µm
• Length / Diameter ratio (L/D) > 3
> The TAFs size criteria as defined by AFSSET, i.e. :
• 0.02µm < D < 0.2 µm
• L > 5 µm
• L / D > 3
> The SAFs size criteria as defined by AFSSET, i.e. :
• 0.02 µm < D < 3 µm
• L< 5 µm
• L / D > 3
 Sampling and analyses were conducted by laboratories accredited for this
ATEM method and previously trained for applying this protocol7
© C.Eypert-Blaison / INRS

8. Results
 Participation
 29 processes (25 were expected)
 265 results collected (500 were expected)
 All the situations involved asbestos removal except one (maintenance
operation)
> The quantity of data and their distribution across the different worksite types did not allow for
doing exploratory statistical analysis as initially expected. It hasn’t been possible to determine
a statistical relationship between the ACM/technique combinations and the level of dust
generated
 Global results including all the situations evaluated
8
Min (f.L-1) Arithmetic
mean (f.L-1)
Median
(f.L-1)
Max
(f.L-1)
WHO serpentines 1.48 539 18 16,300
amphiboles 1.47 337 5 23,025
Asbestos 1.48 866 38 23,025
TAFs serpentines 1.48 1,742 21 51,450
amphiboles 1.47 91 5 6,358
Asbestos 1.48 1,822 24 51,450
SAFs serpentines 1.48 13,602 190 256,072
amphiboles 1.47 1,220 5 89,655
Asbestos 1.48 14,811 356 256,072
15%
17%
68%
WHO
TAFs
SAFs
Distribution of each fiber size

9. Results (1/2)
 This study showed:
 SAFs >>> TAFs > WHO fibers
 Chrysotile for all worksite types, except one (removal of
sprayed asbestos)
 The highest fiber dust level for WHO fibers + TAFs
occurred with the removal of ACMs:
> Asbestos containing plaster, regardless of the technique used, with
average concentration higher than 11,000 f.L-1, and a maximum
concentration of 60,000 f.L-1
> Sprayed asbestos (though composed of only asbestos in this study –
sprayed chrysotile could have generated higher quantity of TAFs close
to the value observed for asbestos-containing plaster because of its
capacity to generate fibrils that are thinner than amphiboles), with
average concentration of over 6,000 f.L-1, and a maximum
concentration of 29,000 f.L-1
> Paint and coating, with average concentration of over 3,000 f.L-1, and
a maximum concentration of 6,300 f.L-1
> Materials in damaged buildings, with an average concentration of
over 2,600 f.L-1 and a maximum concentration of 21,000 f.L-1
9
© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS
© A.Romero-Hariot / INRS

10. Results (2/2)
 This study showed:
 With the removal technique as the only
criterion, the highest fiber dust level occurred with:
> Scraping with a spatula for WHO fibers
> Ultra high pressure (UHP) for TAFs and SAFs fibers
> UHP for [WHO+TAFs] fibers with average concentration of over
11,000 f.L-1
> Grinding-sanding for [WHO fibers+TAFs] with maximum
concentration of over 60,000 f.L-1
 PCM underestimates asbestos concentration in
comparison with ATEM
> For the same criteria of fibers (WHO by PCM – WHO by ATEM)
> For the criteria defined by WHO including TAFs (WHO by PCM –
[WHO fibers+TAFs] by ATEM)
 For several worksite types, the protection factors of
respiratory protective devices are not sufficient to
protect workers under the limit value
10
© A.Romero-Hariot / INRS
©A.Romero-Hariot/INRS
© Patrick Delapierre for INRS

11. Conclusions
 Metrology and OEL compliance checks
> Setting an 8-hour OEL including TAFs using ATEM counting method is realistic considering
range of dust observed during the campaign
> But it’s necessary to increase the reliability of asbestos dust measurement through the
process of accreditation of bodies in charge of asbestos exposure assessments
> Modify the principle of evaluation by measuring the dust level of each worksite type in order
to adapt collective and individual protection accordingly
> Set up the 8-hour OEL compliance check based on the result of the evaluation which has
been described previously
 Prevention measures & techniques
> Developing removal techniques that avoid direct intervention of operators
> More effective vacuum cleaners (or equivalent systems) have to be developed to reduce
dust emission at the source
> Setting up windows around work areas to enable surveyors to view worksite from outside
the polluted area (reducing people exposed inside polluted area)
> Creating more effective personal protective equipment (clothing and respiratory devices)
> Implementing in each company involved a program for selecting and managing respiratory
protective devices
 Knowledge acquisition
> Conducting studies in order to establish protection factors of respiratory protective devices
in work situations based on ATEM analyses
> Continuing to acquire knowledge about dust level by ATEM (maintenance operations)
> Pursuing studies on the toxicity of SAFs
11

12. Titre de la présentation04/07/2014 12
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