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HISTORICAL RESEARCH REPORTResearch Report TM/82/23
1982 A comparison of the effects of different counting rules and aspect ratios on the level and reproducibility of asbestos fibre counts. Part 1: Effects on level. Final report on CEC Contract ‘Counting rules for asbestos fibre measurements at work’ Howie AJ, Crawford NP
HISTORICAL RESEARCH REPORT Research Report TM/82/23
1982
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A comparison of the effects of different counting rules and aspect ratios on the level and reproducibility of
asbestos fibre counts. Part 1: Effects on level. Final report on CEC Contract ‘Comparison of asbestos fibre
measurements at work’
Howie AJ, Crawford NP
This document is a facsimile of an original copy of the report, which has been scanned as an image, with searchable text. Because the quality of this scanned image is determined by the clarity of the original text pages, there may be variations in the overall appearance of pages within the report. The scanning of this and the other historical reports in the Research Reports series was funded by a grant from the Wellcome Trust. The IOM’s research reports are freely available for download as PDF files from our web site: http://www.iom-world.org/research/libraryentry.php
Research Report TM/82/23 ii
Report No.: TM/82/23(EUR P.77)UDC 553.676 : 622.411.512
A COMPARISON OP THE EFFECTSOF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THELEVEL AND REPRODUCIBILITYOF ASBESTOS FIBRE COUNTS
PART I : EFFECTS ON LEVEL
by
A.J. CowieN.P. Crawford
December 1982
Report No.: TM/82/23 (EUR P77)UDC 553.676 : 622.411.512
INSTITUTE OP OCCUPATIONAL MEDICINE
A COMPARISON OP THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF
ASBESTOS FIBRE COUNTS
PART I : EFFECTS ON LEVEL
A.J. Cowie and N.P. Crawford
Final Report on CEC Research Contract : 'Counting Rules for
asbestos fibre measurements at work'
Duration of project : October — December 1981
Research Work carried out with financial aid from the
Commission of the European Communities
Institute of Occupational Medicine,Roxburgh Place,Edinburgh, EH8 9SU,Scotland.
Telephone : 031-667 5131 December 1982
iteporu no» : ii-y u^/ c.3 .cjun i~ ( f j
UDC 553.676 : 622.411.512
INSTITUTE OF OCCUPATIONAL MEDICINE
A COMPARISON OP THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF
ASBESTOS FIBRE COUNTS
PART I : EFFECTS ON LEVEL
A.J. Cowie and N.P. Crawford
CONTENTS
Page No.
SUMMARY
1. INTRODUCTION 1
2. OUTLINE OF STUDY 1
3. WORK PROGRAMME 2'
4. RESULTS AND DISCUSSION 3
4»1 Basic Data
4»2 Effect of Aspect Ratio on the level of count
4»3 Effect of Counting Rules on level of count
4«4 Other Observations from the data
5. CONCLUSIONS 8
ACKNOWLEDGEMENTS 9
REFERENCES 9
TABLES 1-5 11
FIGURES 1-6 31
APPENDICES 1-4 Al
Report Wo.: TM/82/23 (EUR P77)
INSTITUTE OF OCCUPATIONAL MEDICINE
A COMPARISON OF THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF
ASBESTOS FIBRE COUNTS
PART I : EFFECTS ON LEVEL
A,J. Cowie and N.P. Crawford
SUMMARY
The Commission of European Communities (CEC) is currently reviewing
airborne asbestos fibre regulations and an associated reference
procedure for the membrane filter optical method of measuring fibre
number concentrations. The present study arose from a desire by
the Commission to acquire information concerning the effects of
various counting rule packages, including variants in routine use,
on the level and reproducibility of fibre counts and forms part of
a co-operative programme between the CEC and the Canadian Government.
The first stage of the investigation concerns the effects on level
of count, without taking account of interlaboratory variation, and
is reported here.
The counting rules investigated were:
(a) those developed for the United Kingdom's Central
Reference Scheme (CRS) method
(b) a modified form of the CRS rules
(c) those contained in the Asbestos International
Association's (AIA's) reference method.
These packages were each considered in combination with three different
definitions of fibre length / diameter ratio (aspect ratio) viz. >J>'.'\,
>5:1 and >10:1.
Seven European and twelve Canadian laboratories participated in the study.
Each laboratory selected samples from its own stock and evaluated them
using not only the packages described above but also employing its
routine counting protocol. In some cases, the same samples were
(ii)
evaluated by more than one laboratory, thereby providing some
information on interlaboratory variation. Six principal sample types
were incorporated in the study:f mining, milling, asbestos cement,
friction material, textile and insulation.
The effects of aspect ratio and counting rule were found to be
essentially independent of each other but both varied with sample
and sample type.
Increasing the aspect ratio from >3*1 to >5?1 reduced the level of
count on average by 12 per cent; a further increase in aspect ratio
to >10:1 produced an additional reduction of about 23 per cent in the
average counting level.
For a given aspect ratio, the level of count increased in the order
AIAQ modified-CRS (</CRS, as expected from consideration of the
counting criteria. Taking the AIA (>3:1) count as 100, the average
levels associated with the modified-CRS and CRS rules for an aspect
ratio of >3s1 were 125 and 146 respectively, and for an aspect ratio
of>5s1 were 110 and 128 respectively. Counting rules used routinely
by laboratories gave an average level of 122. The CRS (V5:1) and
modified-CRS (>3:l) rules gave counts most comparable on average to
those produced with the local rules.
These differences in level appear to be small compared with the
interlaboratory differences evident from the ;.data'/available., .ifor the
"small .jjada&xjof.' samples which were evaluated by more than one
laboratory. The significance and importance of differences in level
associated with different counting criteria can only be fully
assessed once interlaboratory differences have been quantified.
This is the aim of the next stage of the investigation and will be
reported upon separately.
Report No.: TM/82/23 (EUR P7?)
INSTITUTE OF OCCUPATIONAL MEDICINE
A COMPARISON OP THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF
ASBESTOS FIBRE COUNTS
PART I : EFFECTS ON LEVEL
A.J. Cowie and N.P. Crawford
1. INTRODUCTION
The Commission of European Communities is presently considering the
question of airborne asbestos fibre standards and an associated
reference procedure for the membrane filter optical method of
measurement. This method involves manually counting fibres rendered
visible by phase contrast microscopy and was developed by the Asbestosis
Research Council (ARC, 1971). Variants of the method are currently
in use in different countries. The Commission required information
regarding the level and reproducibility of results obtained by use
of existing and proposed variants to facilitate decisions concerning
the reference method. Consequently, an investigation involving a
number of laboratories was initiated in March 1981 within the framework
of a co-operation agreement between the Commission and the Canadian
Government,
The programme was envisaged in three stages: -
Stage 1 Assessment of the relative counting levels obtained using
a variety of counting rule packages, without taking into
account the inter laboratory variability o
Stage 2 Comparison of selected counting rules with respect to the
magnitude of intra- and inter- laboratory variation.
Stage 3 Action to reduce intra- and inter- laboratory differences,
establishing, if necessary, a continuing quality control
programme,,
2. OUTLINE OF STUDY
This report describes the work carried out in Stage 1 of the programme.
Various counting rule packages were considered in developing a protocol
for the first stage of the study. The variations in counting criteriain routine use include differences in the basic definition of the
length, diameter and length/diameter ratio (aspect ratio) of a fibre;:,
In addition, differences arise in the counting protocols applied to
complex fibre configurations e.g. split fibres, fibres in contact with
particles and fibre bundles. Different methods of counting fibres
crossing the perimeter of the field of view to be evaluated are alsoin use.
2.
The most common definition of a fibre specifies a minimum length
of 5 /un and a maximum diameter of 3 Jim, subject to a minimum aspect
ratio of 3:1. Throughout this investigation, the length and
diameter specifications were retained but three aspect ratios, namely
>3:1, >5:1 and >10:1, were considered. This takes account of the
biological and mineralogical evidence which has emerged (WALTON, 1982)
suggesting that an aspect ratio between 5*1 and. 10:1 may be more
appropriate. The D-22 Committee of the American Society for Testing,
and Materials has included the>5:1 aspect ratio definition in the
present draft of its test method.
The counting rule variants considered for this study were:
Central Reference Scheme (CRS) rules, These form part of a reference
evaluation method developed in Britain and, as such, have been used
to compare the performance of different methods and laboratories
(CRAWFORD, To be published).
Asbestos International Association (AIA) rules. These form part of a
reference method developed by the AIA (AIA, 1979) in "an attempt by the
asbestos industry to reach international agreement". It was hoped that
publication of this method would "motivate a review of the various
national methods so that results from different countries become more
comparable".
Modified-CRS rules; These were developed during discussion in the
planning stage of the present investigation and therefore have hitherto
not been used.
The CRS and modified-CRS rules embody the principle of minimising the
number of decisions microscopists have to make; the AIA rules involve
making more decisions.
The first stage of the investigation examined these three counting
rules, each in conjunction with each of the three aspect ratios mentioned
above, and made comparisons with the local counting rules in routine use
at the laboratories concerned.
2>. WORK PROGRAMME
Seven European and twelve Canadian laboratories took part in the first
stage; these are listed in Appendix 1.
The planned work programme is detailed in Appendix 2. The three sets
of counting rules are defined in Appendix 3 and can be summarised as
follows:
CRS rules; All fibres are counted individually, whether or not
they appear to be attached to other fibres or particles.
AIA rules. Not all fibres are counted individually; some fibres
are not counted if they appear to be attached to other fibres or
particles,
Hodified-CRS rules. All visibly-free ends of fibres are counted
and the total divided by two to obtain the fibre count.
Each set of counting rules was used in conjunction with three different
aspect ratios viz. >3:1, >5:1 and >10:1. Each combination of counting
rule and aspect ratio was considered as a counting rule package, making
nine basic packages. In addition all local counting procedures used
by participating laboratories were included; these incorporate the same
aspect ratio (>3:1) but some did not limit fibre diameter.
Samples were to be selected in pairs by each laboratory covering a
range of asbestos and process types. Evaluation was to be carried
out on two separate days following the scheme detailed in Appendix 2,
In practice, however, differences occurred between laboratories both
in the type and size of graticule used and in the implementation of
the planned programme. Respective details are given in Table 1 and
Appendix 4o Throughout this report, individual laboratories have
been given alphabetic codes.
The resulting set of data was consequently complex in nature and related
to a total of 60 samples which represented seven different types of
sample. It was considered that an informal treatment involving the
summarisation and presentation of the data in tabular and graphical
form would provide an indication of the relative levels of count obtained
using the different counting rule packages. The comparative sparseness
of the data restricts the amount of additional relevant informationrecoverable through the use of more formal methods, and, since it would
be necessary to allow for the possible dependence of count variability
upon sample density and area of filter evaluated, it was decided that
the additional time and cost involved in a formal analysis of the data
could not be justified,
4. RESULTS AND DISCUSSION
4o1o Basic Data
The number of fibres counted and the corresponding number of fields
evaluated are recorded in Table 2 for the samples evaluated by each
laboratory. For almost all samples, the evaluations using the various
4.
combinations of counting rule and aspect ratio;'} criteria were repeated
on two separate days*
Table 3 contains the corresponding fibre densities (f/mm2) calculated
using the graticule field areas in Table 1. The data in Table 3 are
grouped by sample and form the basis of the comparisons described below.
4.2 Effect .-of, .-Aspect/Ratio on the Level of--.Count
In all evaluations, counts at all three aspect ratios within a given
package were obtained on the same fields of view. This was in
accordance with the planned programme (Appendix 2). The effect of
varying the aspect ratio criterion upon the level of count obtained
for the five pairs of milling samples can be seen in Figure 1. Pour
of these pairs were evaluated by more than one laboratory. The counts
obtained with aspect ratios of >5:1 and >10:1 have been expressed as
percentages of the corresponding >3:1 count.
Within a laboratory, the effect of aspect ratio does not vary greatly
from day to day, is not strongly dependent upon the counting rules
used and is generally similar for paired samples. However, the effect
of aspect ratio varies between different laboratories in their evaluation
of the same sample. Similar patterns were also found for the other
types of sample (not illustrated).
Table 4 summarises the effect of changes ttn aspect ratio both for each
sample type and overall. For each counting rule package the counts
are related to the >3:1 aspect ratio. For each sample type, the
percentages were calculated as the arithmetic means of individual
sample ratios Busing all the counts produced by the different laboratories.
The overall percentages are arithmetic means of the sample type values.
Within any particular sample type and also overall, the effect of aspect
ratio is essentially independent of counting rule package. This is
a consequence of the pattern described above for single samples. Despite
the fact that only a few samples of each type have been included in this
investigation, the effect of aspect ratio appears to vary from sample
type to sample type. For each counting rule package, an increase in
aspect ratio from >3:1 to >5:1 gives an average reduction in counting
level of some 12 per cent, with an overall reduction of around 35 per
cent being associated with an aspect ratio: ; increase to >10:1. These
values are consistent with results obtained by WINER and; COSSETTE (1979).
4.3 Effect of Counting Rules on Level of Count
The planned protocol envisaged each counting rule being applied
separately to different fieldSo In practice, some laboratories applied
all three rules to the same fields, thereby eliminating between-field
variability inherent in the planned protocol. An examination of
Table 3 indicates that, for a given ratio, the three sets of counting
rules yield fibre density estimates which are generally in the order:
AIA<CRS-MOD<CRS. This is true for either protocol and is consistent
with what is to be expected from consideration of the details of the
counting rules described in Appendix 3« Since the effect of changes
in aspect ratio are virtually independent of counting rules, it was
decided to restrict detailed comparison of the counting rules to the
conventionally used aspect ratio of >3:1 and the modified CRS rules
at >5:1.
Fibre densities obtained using the modified-GRS : method at aspect
ratios of >3:1 and >5:1 are plotted in Figure 2 and 3 respectively
against the corresponding values with AIA (A.R. >3:1) method. In
these figures, the duplicate evaluations of a sample on the two days
have not been averaged but have been plotted as separate points.
Figure 2 indicates that the modified-CRS , rules (A.R. >3:1) in almost
all cases give values higher than the AIA rules (A.R. >3:1) whereas there
is less evidence of a systematic difference between counts produced by
the modified-CRS rules (A.R. >5:1) and the AIA rules (A.R. >3:1)
(figure 3)o In the latter case, however, the variability of the
relationship is somewhat greater0
Figures 4 and 5 illustrate the relationships between counts made on
individual samples using the modified-CRS (A»R. >5:1) and the AIA
(A.R. >3:1) rules respectively and counting procedures used routinely
in the various laboratories. The AIA (A 0 R« >3:1) rules in almost all
cases give lower counts than the local rules (Figure 5) whilst counts
with the modified-CRS (A.R. >5:1) and local rules were more scattered
about the 1:1 line (Figure 4).
There is no evidence from Figures 2 - 5 of any obvious effect of fibre
density on the overall relationships between counting rule packages.
In addition, an informal examination (not detailed here) of the paired
sample data revealed no systematic difference in relationships between
packages at high and low densities.
6.
Examination of Figures 2 and 3 indicates that some of the observed
variation in the relationships appears to be associated with sample
type, e.g. the asbestos cement samples. The average level of count
from all the various counting rule/aspect ratio combinations relative
to the AIA (>3:1) count is given in Table 5 both for each sample type
and overall. The method of calculation was essentially that used to
derive the data presented in Table 4«
The following observations are made concerning the values presented
in Table 5.
1 . There appear to be differences in the relationships between counting
packages with sample type. However, the values in Table 5
derive from a small number of samples of each type. In
addition, it is not possible to separate completely the effects
in the data of laboratory and sample type since different
samples were evaluated by different laboratories,
20 For each sample type and aspect ratio, the relative levels of
count are in the order AIA modified-CRS < CRSo This reflects
the consistent pattern previously noted for the individual sample
data in Table 3.
3* For each aspect ratio the relative counts using the modified-CRS
rules generally fall mid-way between AIA and CRS counts, both
for each sample type and overall.
4. For the 3:1 aspect ratio, in current use universally, the overall
relationships given in Table 5 between the AIA, CRS and modified-
CRS rules are broadly comparable to those observed in a recent
laboratory intercomparison study primarily on asbestos cement
samples (U0 Teichert - personal communication). The values
listed in Table 5 for asbestos cement samples are numerically
higher than those observed by Teichert but the latter exercise
provided more extensive data from about 60 samples.
Local counting rules produced higher counts than the AIA rules
(A.R« 3:1) for each sample type, on average being 22 per cent
higher; the counts were lower than the CRS rules (A.R. >3:1)
by a similar amount.
7.
The modified-CRS rules (A.R. >3*1) generally yielded comparable
counts overall to those made with local rules.
Overall counts obtained using all the various packages under
consideration increase in the order:
AIA (>10:1)
AIA (>5:1) » Mbd-CRS (>10:1)
AIA (>3:1) « CRS (>10:1)
Mbd-CRS ( 5:1)
Mod-CRS (>J:1) & CRS (>5:1) ~ LocalCRS
,4*4' Other Observations from the IJata
Repeat counts were made by each counter on two separate days, this
being intended to provide some information on the comparative
repeatability of different counting rule packages. However, v the;
sparseness and complexity of the data provided measures of within-
counter variability which were insufficiently reliable to permit
firm conclusions to be drawn concerning the effects of counting rules
on repeatability.
No provision was made in the planned protocol for evaluation to be
made on the same sample by different laboratories. In practice,
however, about one-third of samples were counted by more than one
laboratory. This provides some information concerning inter-
laboratory variation. Figure 6 shows plots for mining samples of
the ratio of fibre densities obtained with the modified-CRS (A.R.>3:1)
and AIA (A.R.>3!1) rules by different laboratories. These plots
illustrate three aspects of the observed variability in the
relationship between these counting rule packages:
(a) the variability of the ratio from day to day within
a counter
(b) the range of the ratio for different samples evaluated
in the same laboratory (Figure 6a)
(c) the variation in the ratio for the same sample
evaluated in different laboratories (Figure 6b) .
In particular, it should be noted that the inter-laboratory differences
(c above) in the relationship are often large and of the same magnitude
8..
as the differences between samples observed within laboratories
(b above). These components of the observed variability are
generally larger than within-counter variation (a above) and
differences in level between methods (Table 5). The relationships-\_/between the CRS-l/DD (A.R.>J:1) and AIA (A.R.>3:1) fibre densities for
other types of sample evaluated by different laboratories show similar
features. These features also characterise the relationships between
other pairs of counting rules (at the same or at different aspect ratios),
Intra- and inter-laboratory variation over a range of samples, will be
examined in more detail in the second stage of this investigation.
;5. CONCLUSIONS
This investigation aimed to produce an indication of relative counting
levels obtained using various counting rules and aspect ratios,
without taking account of interlaboratory variation.
The effects of aspect ratio and counting rule are essentially
independent of each other, but both vary with sample and sample type.
An increase in aspect ratio from >3:1 to >5*1 reduces the level of
count on average by 12 per cent (Table 4)- A reduction in average
level of about 35 per cent is associated with an increase in aspect
ratio from>3:1 to >10:1.
For a given aspect ratio, the level of count increases in the order AIA
v<modified-CRSf<CRS. This is the order expected from consideration
of the counting criteria principles. If the AIA (>3sl) counts are
taken as 100, the average levels associated with the modified-CRS
and CRS rules for an aspect ratio of 3J1 are 125 and 146 respectively
(Table 5) and for an aspect ratio of 5*1 are 110 and 128 respectively.
Counting rules used routinely by laboratories gave an average
relative level of 122. The CRS (>5:1) and modified-CRS(>3:1) rules
therefore give counts most comparable on average to those produced
with the local rules.
These differences in level appear to be small compared with the inter-
laboratory differences evident in Figures 6a and 6b. The next stage
of the investigation will examine interlaboratory differences in
relation to the use of a few selected counting criteria and establish
whether or not better interlaboratory consistency is associated with
particular counting rules. The significance and importance of
differences in level associated with different counting criteria can
only be fully assessed once interlaboratory differences have been
quantified.
ACKNOWLEDGEMENTS
The authors are grateful to the staff of each of the laboratories for
their participation and co-operation in the investigation and to
Mr. G.W. Riley for co-ordinating the work carried out by the
Canadian laboratories.
REFERENCES
ASBESTOS INTERNATIONAL ASSOCIATION (1979) Reference method for thedetermination of airborne asbestos fibre concentrations at work-places by light microscopy (membrane filter method). London:AIA (Recommended Technical Method No. 1).
ASBESTOS RESEARCH COUNCIL (1971) The measurement of airborne asbestosdust by the membrane filter method. Rochdale (Lanes): ARC...(Technical Note 1. )
CRAWFORD NP (To be published). The United Kingdom Central ReferenceScheme for airborne asbestos fibre evaluation. Report presentedto CRS Steering Committee.
WALTON WH (1982). The nature, hazards and assessment of occupationalexposure to airborne asbestos dust: a review. Annals ofOccupational Hygiene; 25: 115-248.
WINER AA, COSSETTE M. (1979) The effect of aspect ratio on fibrecounts: a preliminary study. Annals of the New York Academyof Sciences; 330: 661-672.
10.
11.
TABLE 1
Type and Size of Graticules used
by Participating Laboratories
LaboratoryCode
A
B
C
D
E
P
G
H
I
J
K
L
M
H
P
QR
S
T
Graticule.; . /Type
Porton
Porton
Porton
Porton
Porton
Porton
Porton
Walton-Beckett
Porton
Walton-Beckett
Porton
Porton
Walton-Beckett
(Wai ton-Beckett(BS3625
Walton-Beckett
Walton-Beckett
Walton-Beckett
(Walton-Beckett(BS3625
PattersonGlobe & Circle
Shape
Square
Square
Square
Square
Square
Square
Square
Circle
Square
Circle
Square
Square
Circle
CircleRectangle
Circle
Circle
Circle
CircleRectangle
Rectangle
Area(mm )
.003
.0025
,0025
.00308
.0025
.0041
.0025
.00785,00325
.00785
.0029
.00489
.00785
.00785
.0048
.00785
.00785
.00785
.00785
.01165
.00587
TABLE 1
TABLED. ' - * ' .
Htmber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/OQ Hi r>^ AuclttlpXO
No.
A 201-
A 101
A, 202
A 102
B:301
B 302
B 401
B 402
B 501
B 502
AIA
No. ofFields
100100 .
100100
100100
100100
100100100100100100
100100
100100
100100
No. of Fibres>3:1 >5:1
7480*
84*75*
126121
107*105
3741*92
104
4145*
23175256
1923*
66666057*8288
8473
2425
57*61*
35*39*18*14*2828*
1314*
>10:1
5252
3945*565955*4516*19384321*25*11*9*
17*18
45
CRS - Modified
No. ofFields
****
****
****
****
****
*#**
#*#*
»***
****
»***
No. of Fibres>3:1
75*80*
8575*
126121
107*105
4$92
109*
4145*
2318
5456
1925
>5:1
67*66*
6057*
8588
8473
23*26
66*
36*39*18*14*
2928*
13.16
>10:1
52*52*
3945*5659
55*.45
1720
3946
2425*129*
17*18
45*
CRS
No. ofFields
****
********
****
****
''.********
****
#***
****
No. of Fibres>3:1 >5:1 >10:1
8586
8780
127125108108
4255
1241356261
3027
6567
2435
7670
6262
8890
8575
27338083
5553
2422
35341624
57554050
5962
5748
1825
5458
34341615
2322
68
LOCAL
No. ofFields
****
#*******
-**»»#*****»** ***
**##***#
**
No. of Fibres>3:1 >5:1 >10:1
7581*
85*77*
126121
111*106
3*95
10842*45*
2318
5357*2023*
6766
6058*
8588
867424*25
63$
3739*18*14*
2928*
1314*
5352
3945*565955*45
1719394522*25*11*9*
17*18
45
** On each day only one set of fields was examined and the various counting criteria were applied in turnto each individual field.
TABLE 2-
Number of Fibres Observed and Number of Fields Evaluated in Comparison pf Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleNo.
C 211
C 212
C 1-11
C "1-12
D 221
D 222
D 121.=#
D 122
E 221
E 122
AIA
No. ofFields
100100
100100
100
100100
100100
100100
100100
100100400400
100100
No. of Fibres>3:1 >5s1 >10:1
444372*
_ 49*1711
20*294025*
145*172*
50*59
6987*
108123*111120*
•
11*1722*17••;g
4
6*7
37*18
122154*40*50
54*7495
104*92
102*
2*7
116
4*114476i
21*37
1312*1016
6454
42473
CRS - Modified
No. ofFields
*»**
****#***
** :**
#***
***#
***»
***#
*»**
****
No. of Fibres>3:1 !
5248*86*68
43*19*
3539*5943
261*277
77*79
111*116*
113125
113122*
>5:1 :
15*21
32*32
265*
15*145236*
233256
5862
8143*
100106
95104*
>10:1
2*10
15*20t
181
610
6*6*
3169*2016
1620*6855*
42*74
CRS
No. ofFields
****
**** • •********
********
»«**
**
*•»#*
****
No. of Fibres^3:1 >5:1 >10:1
6657
114896125*
4448
6349
286305
9595
133129129141122139
1928
5248
377
2218
5641
268281
686998
100
114120
103119
413
2531
251
1113
99
2988
2318
2121
8260
4586
LOCAL
No. ofFields
*#****#*
•* •
****
*#** •***#******
. **
«#»»**•***
No. of Fibres^3:1 >5:1 ^10:1
45*468f iyf58*
1.911
24*334327
152183*6567*
94*113*128
117*124
11*172618
10*4
8*7
39*18*
122*158*
50^56
S96
103*
94*102*
2*7
127
*"51
3•4*
6*6*
21*40
1715
IS645442*73
** On each day only one set of field was examined and the various counting criteria were appliedin turn to each indivudual field.
TABLE :2
Ntmber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleNo.
E 121
E 222
F 222
F 221
G-131
5^32
H'111
H 301
H 41 1
H 211
AIA
No. ofFields
200200
100100
too100
197200
100100
100100
100100
100100
100100
106100
No. of Fibres>3«1 >5«1 10:1
105103*
115121*
355*304*
107*119
79*49i80*84*
4541
115129
3136
123128}
a103*109
304*276
94*101*
35*173436
31151273036
119*123*
3849*
7272*
244*224
Bt72
710
13U*90*93*2935
107*81
CRS - Modified
No. ofFields
***»
*»**
***»**
**
*»**
****
100100
100100
100100
100100
No. of Fibres>3:1 ;
107*107
125130
371*332*
113
102*969683
5158*
128*128*
5237*
166*133*
>5:1
7985
113*117*323*3041011.08*
42*3439314450
124123*5136*
156*
>10:1
•g81*79
266*25672-
-78*
76*
9*7
1830*
103*91*
4933
14699
CRS
No. ofFields
*»**
** ,***#«#»**»
****#**»
100100
100100
100100
100100
No. of Fibres>3:1 ?5:1 >10:1
111117
139146
441399138*156
93*91*98*87
4950
1451572850
149172
8291
128^132"
386367
123*133
3632
41*34
4443
1421552848
141163
4158
9391
321316
87*98
798*7*
2323
115128
2843
133129
LOCAL
No. ofFields
*#
****
****
#***
****
****
No. of Fibres73:1 >5:1 ?10:1
111*113
123132
375*321
108*120
6476*
8687*
77*81*
105*110
316285*
95*101*
27*31*
3736
%
250229*
7373*
4*8
78
•p*
** On each day only one set of field was examined and the various bountlng criteria were appliedin turn to each individual field.
TABLE ? " " . . ' • -
Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/
No.
HJ12
H.412
H 212
H 302
H.601
H 801
H 511
r 61 1
1-601
I 512
AIA
No. ofFields
100100
100100
100100
100100
100100
100100
100100
5552
100100
9196
No. of Fibres>3:1 >5*1
8367*61*48*
248*163332315*
9693*80*78
9$127*132*
9591
115113
76536048*
222145321*2909691*52}44*
44*45*
12011992*90
109*109
>10:1
52^. 27
57^44
150J93i
274^244886831617
CRS - Modified
No. ofFields
100100
100100
100100
100100
100100
100100
41-jl 10036| 100
1103110
90389
104106
****
****
****
No. of Fibres>3:1
149*74
103*82
281207
292*361
200186
9594
1064-8gJ
77
157144*115108
142*123*
>5:1 '
14065
103*82
256*191282*342
200182
6749*
10582*
149*131*112*107
137119*
>10:1
11633*9875
198*137248*300194155
1&94,64*
140119*110*106
132116*
CRS
No. ofFields
100100
100100
100100
100100
100100
100100
'100100****
****
**#*
No. of Fibres>5:1 >5:1 >10:1
13485
134107229193343448251234116124100103186166
135129
171134
12877
131105
208185332438
249233
8380
98101
178152
132128
165129
9741
12694
156136283382
241211
3732
8976
168139
130127
160126
LOCAL
No. ofFields
****
****
»***
No. of Fibres73:1 >5;1 >10:1
•
175164128129*147*139*
167150*
125*128*
142134*
..
157*141*123*127*136*131*
** On each day only one set of field was examined and the various counting criteria were appliedin turn to each_lndividual field.
TABLE 2 ' - . . - •
Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/On vrv«*1 AsampleNo.
I 202
I 201
J 231
J 232
J ;131
J.-*I32
K 621
K 512
K 511
K'232
AIA
1No. ofFields
7987
100100
100100
6594
100100
100100
2520
6672
100100
8357
No. of Fibres>3:1 >5:1
119115
53464
10198
1221414
92457l
73
1131109}
50*60
8874;
102100
66341
49*54 35
1014! 1011112| 109
102-J 991251 1211
47564
130102
45
55*123*97
>10:1
1001041
4454
2730
28
40*1310
6410
95499
894109
38474
109483
CRS - Modified
No. ofFields
*#
***##*
100100
7092
100100
100100
2729
4447
100100
6040
No. of Fibres>3:1
119118
62!60
1121061
13311421
60l841
60
60*100107
101101
561611
101100
>5:1 '
113110*
59*56*
94f
74*102100*
44*50
4338
97104
95*96*52
60*9899
>10:1
101106
52*511
294-241
4434
1218
1418
9Cl102
8591
411511
8888
CRS
No. ofFields
#*#*
****
100100
5665
100100
100100
3020
2936
100100
4336
No. of Fibres>3:1
129134
7167
10983
121129
9171
9471
101120
100104
7157
100104
123126
6863
8762
100100
6357
7248
100117
94101
6356
9698
>10:1
111120
6058
3128
3235
2621
2319
97'109
8390
5547
8985
LOCAL
No. ofFields
******
**
100100
8590
100100
100100
2624
3244
100100
3452
-No. of Fibres
>-3:1 >5:1 >10:1
128*128*
6268
8285
1401441
84l615960
10211021
1021021
484-541
100!1021
122122
5964
6763
99]101J
534
32*4440
10C&-100
9697
48524
93|98^
1081164
5258
17181
• 3240
1984
7.8*
93484
80844
35450
7585
** On each day only one set of field was examined and the various counting criteria were appliedin turn to each individual field.
TABLE 2 : .
Ntanber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleNo.
K 231
K.132
K 131
R-..401
K 402
K 302
K 301
L 112
L 111
L 1.01
L 102
AIA.
iNo. ofFields
6766
100100'
100100
100100
100100
3550100100
94100
10085
6683
No. of Fibres>3:1 >5:1
101101
514.41!
'4p|
174164
2922
1004101 .
7OL=L265s
12596154i
128114
95984637459f34i1741542520
96492
704
1064
84496108
1041094
>10:1
85480
314OO=-
4721
it
241980|
64456f997246648772784
CRS - Modified
No« ofFields
4946100100"-
100100
100100
100100
3135100100
V**.
#*
***#
***#
No. of Fibres>3:1
10041004
58624
101477
42354784574107100
874103
1414102
165411715141234
>5:1
9449&4444448546541433475456|9649984100
1199212641104
13141144
>10:1
8775232357533832470455479874754883-
112
77934884
944794
CRS
No. ofFields
6250
100100
100100
100100
100100
2928
10089**
**
****
***#
No. of Fibres>3:1
10310968761196764637768107100
123100
145100
191116181125
>5:1
1001035964104526161
776510197
1189912390146
161116
>10:1
9190
4936753859547262878910890
116
78103864118
i
804
LOCAL
NO a OfFields
6966
100100
100100
100100
100100
3433100100
No. of Fibres>3:1 .
1274101
5584498974454
. 4447046012111548176
>5:1
117-i
90444472
84!434169460
11310976|68g
>10:1
957722476161
394344684578889461
"t
594
** On each day only one set of field was examined and the various counting criteria were appliedin turn to each individual field.
TABLE 2
Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Oft iyit-«1 Aoampj.9No.
L 132
E 1.31
L 1,21
L 212
L 211
L 201
L 202
L 232
L 231
L 221
AIA
No. ofFields
100100
100100
100100
66
50100100
81100
52696666
4450
No. of Fibres>3:1 >5x1
59458498|
14278
1034-
13641316341351144
122122
11141154
113131
424517464
10571
934
126
107504105914
1034105
1054103410713T;
>10:1
18433451436863
764
113467430g614524
76486
8280
9441234
CRS - Modified
No. ofFields
****
**
****
**
**
*#**
********
****
•**•.•**
No. of Fibres>3;1
73461
10578
157794
113
141134463
14241174
128123
11641164
1174132
>5:1
5353483464-2
120724
10341314111450
1124944
1094106
110410441114132
2536
564434
82634864
11974304684554
80487
87814
991244
CRS
No. ofFields
****
****
*#**
**
**
****
. ****
************
No. of Fibres>3:1 :
8462
11180
173481
1194
1481444641491214
1354123
12041171224133
>5:1
5954491664
134474
109
13841214511199&4
117106
11441051164133
>10:1
303762454
9465
92
12682304
744594
8787
9182
1041254
LOCAL
No. ofFields
•,
No. of Fibres5:1 >5:1 >10:1
t
00
** Onin
each day only one set of field wasturn to each individual field.
examined and the various counting criteria were applied
TABLE 2
Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleNo.
L 222
L 302
L 301
L 411
L 412
B.:701
H -702
Mr-31 1
M-312
M-421
H'422
AIA
No. ofFields
4350
37603826
2624
24
100100
2222
3237
100100
96100
No. of Fibres>3:1 >5:1
121140
114133105108*
129*109
96
82*73*
103105102103*
35*42
10499
100 I 28100 I 39
105117
102*106*
100104*
109*104
94
79*73*
102104100100*
35*38*
10093
23*34
>10:1
80*97
83*8789101
105101
92*
7065
98100
75*71
2932
8879
1621
CRS - Modified
No, ofFields
*#
**
********
***#
**
92100
2020
3132
100100
5973
100100
No. of Fibres>3:1
124143
125134*108*109
129*110
99
too*103*
116100
104108
43
45*101*106*
55*46
>5:1 >10:1
108120
113*108
103*105
109*105
97
100*101*
116100
101*105
43
42*1004-101*
44*40
85100
92*
88*
92*101*
105102 '
95*
97*
96*116100
75*74
33*
35*91
88*34
32*
CRS
No. ofFields
****
********
****#*
7699
2020
2528
100100
5360
100100
No. of Fibres>3:1 >5:1 >10:1
131*146
133*137
113109*
130*116
103
102101
129149
105104
4441
103107
6366
115*123
122110*108105*
110*111
101
101101
129149
104102
4439
101100
5656
90*103
10191
97102
106108
99*
98: 96
1291498473
4032
8991
3942
LOCAL
No. ofFields
•
5861
100100
No. of Fibres>3:1 >5:1 >10:1
104105
6163
100100
5456
*
7885
43
+* On each day only one set of field wasin turn to each individual field.
examined and the various counting criteria were applied
TABLE 2
-
e
IVJ
Number of Fibres Observed and Kxaber of Fields Evaluated in Comparison of Counting: Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleHo.
M423
M 424
M"*25
N. :321 ,
N 322
P 331 :
P 332
P 431
P 432
P 241
AIA
Ho. ofFields
100100
100100
100100
5056
100100
100100
100100
100100
3440
4350
Ho. of Fibres>3:1 >5:1
17*36
53*67*
a133135104*103*
9490*
265295
91109*
108'108*
103*107
153150*60*
ii100101*
97*84
92*85*
244*222
86*10$
103107*
99*105
>10:1
1019*33*4286*
64618065
73*70
209196
7$
7774*
6340*
CRS - Modified
No. ofFields
100100100100
100100
3647
100100
100100
4050
85100
3750
5667
No. of Fibres>3:1
42*4584793730*
108*128*
134*103
102*112*
106*122
1054-134*
114144*
124123*
?5:1 '
39*42*
77743025*
101*101
1148797*96*
97*113*
103124*110*142*
106*107
>10:1
26336261
2316*68*59*9268
88*83
89*104
98*1 < o.li1 1 C 2
107*134*V
91*97
CRS
No. ofFields
100100
too100
100100
4643
10086
100100
5050
100100
3125
3456
No. of Fibres>3:1 >5:1
404382
105
3952
1411371521249379
128137
125122
128105
108112
373876983244
102102
1331068878
120131
122117
126103
101102
>10:1
2230
56792726
65719690
8574
113127
114115121101
9592
LOCAL
Ho. ofFields x
100100
100100
100100
8696
100100
-
Ho. of Fibres^3:1 J>5:1 >10:1
45439180
4534
202203101109
4038
83773725
23256658
3317
.'
•
TABLE 2 -;
Number of Fibres/Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/otuupXuNo.
P 242.
Q 341
•*,wQ 441
Q-451
, Q, 452
R 141
R 142
:R'521.
. R 522•
AIA
No. ofFields
100100
100100
5480
62100
100100
100100
100100
5252
7580
4544
No. of Fibres>3:1 >5t1
137,128*
6556
101*103
106101*
40*
2$
58*46*
110*123*
105*110*
111*101
127*121
6355
100100
10092
46*37*
26|
57*43*
102100*
100*100
100*101
710:1
77*61
3$
tt72*64
3*1
It4428
77*71*81*87*
8296*
CRS - Modified
No. ofFields
10082
100100
6872
7986
100100
100100100100
403158
59
2738
No. of Fibres>3:1
142*115
62*64
106103
104105
3$34*37*
74*47
141115
103*109*
106104
>5:1
12198*
61*64
106103
102*100
66*573235
71*43
103103100105
101102
>10:1
99*92*
46*53
9889
74*77
43*40
$5838
7277*
9697
9498*
CRS
No. ofFields
8254
93100
68"58
5477
100100
too100
100100
293r5539
2021
No. of Fibres^^f 4 */ • " 4
143106
12069
1-17111
106108
81*72
35*378860
133133i109106
112108
>5:1
134100
11864
109
103100
76*69
3133
7555
102100
101100
108102
>10:1
12497
9356
9391
7657
56*45
2126
5438
93••773
9290
10599
LOCAL
No. ofFields
100100
8276
7896
100100
too100
-'
No. of Fibres>3:1 >5:1 >10:1
78*51*
100*100
100100*
41*50
3526
*""' "*-, •
TABLE 2
Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories
Lab/SampleNo.
S 531
S 532
< S 541
S 542
T 461
T 462
AIA
No. ofFields
100100
100100
100100
100100
45•f
98
, No. of Fibres^3:1 >5:1 *>10:1
H14 r?*\\\ P4»2
3242
59}65*
168210J-
9696
8888
133* 123}138 B12t1•
37*
5957*
153184
9595
87*
1731*
49}47*
135155
76*
8281
CRS - Modified
No. ofFields
•f
+
No. of Fibres>3:1
&88}
>5»1
94}94*
87}
>10:1
it8181
CRS
No. ofFields
J
. +•f
No. of Fibres>3:1 >5:1 >10:1
9394
9395
9293
9294
1
7271
8585
LOCAL
No. ofFields
100100
100100
100100
100100
• ' * • - '
+
No. of Fibres/>3i1 >5:1 ^0:1
204241
4355
87119
270278
100100
8585
177216
3446
72108
231250
9999
8484
151187
2635
6595
210217
7777
7878
+ Only one set of fields were examined per sample; the fibres in each field were carefully measuredand drawn onto cards. These drawings were then assessed by two counters independently accordingto the various counting criteria.
23.
TABLE 3
Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type -
Sample No,
Lab . Code
101 A*
L,*
102 A*
L*
111 C*
L*
E.
112 C*
L*
ff
121 D*
B*
L*
122 »*
S*
131 o»
L*
f
K
132 G*
L*
J
K
Hi a
142 R
Observed Fibre Density (f/mm^)
AIA
>3:1 >5t1 >10:1
282 200 130252 192 152
274 196 136278 260 209
353 280 185350 243 150
397 322 223292 270 193
68 36 1844 16 4
196 173 148
57 45 1752 44 18
82 26 4116 28 18272 232 215
106 97 6786 68 34
164 131 42192 162 41
210 153 76207 163 99290 215 139160 145 129
224 177 32284 240 52444 368 170482 410 292
318 142 28198 68 8
201 151 104161 131 88118 84 1773 44 13
253 205 162140 119 72
322 136 28338 144 40
122 87 38120 104 6993 63 869 45 13
178 159 109143 129 78
75 73 5659 55 36
271 250 1 90303 246 175
CnS - Modified
>3:1 >5:1 >10:1 .
283 200 130252 192 152
338 259 191281 266 213
353 280 185. 350 243 150
469 407 293304 282 196
174 104 7278 22 4
209 188 157
65 56 2375 64 39
140 62 24158 56 40
308 259 244190 178 14894 83 43
252 188 65256 201 52
215 158 79214 170 105321 245 168163 143 130
362 263 52378 304 67452 380 170490 418 296
410 170 28384 136 26
215 171 116160 132 89
77 57 15108 64 23
350 295 197266 224 183
384 156 38332 124 28
150 108 51125 109 7476 55 1877 48 10
200 153 79216 160 79
95 91 7460 55 48
449 328 229473 423 318
CRS
>3:1 >5:1 >10:1
290 207 133267 207 167
391 299 211279 263 208
360 283 1 90360 250 160
561 499 366306 266 198
244 148 100102 28 4
204 184 160
62 56 2964 55 29
176 88 44192 72 52
315 268 252
171 163 124108 98 52
308 221 75308 224 58
222 164 «2234 182 116
355 275 192166 151 133
432 318 68419 325 68488 412 180556 476 344
374 144 28366 128 36
227 186 127164 136 93116 80 3390 73 27
410 359 259231 179 131
394 166 34348 136 30
172 121 61127 111 76120 92 2990 61 24
234 203 169262 221 124
112 96 6976 70 48
584 448 409547 411 316
LOCAL
>3:1 >5:1 >10:1
285 200 130258 195 152
372 287 185353 247 150
76 42 2044 16 4
98 34 12132 28 18
211 164 55219 182 49
223 155 77226 163 99
271 213 44307 258 54470 378 170496 410 292
256 110 18306 126 32
108 68 2478 41 11
338 295 210336 291 210
344 148 28350 144 32
75 53 976 51 11
190 153 76291 248 162
-
*Explanation of Sample No.: 1st digit indicates sample type. Paired samples havenumbers with identical 1st and 2nd digits.
•On each day only one set of fields was exaniined and the various counting criteriawere applied in turn to each individual field.
TABLE 3
Sheet 1
24-
TABLE 3 ' . . .
Fibre Densities Obtained by Various Laboratorleo in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Milling
Sample No.
Lab. Code
201 A*
I*
L?
202 A*
I*
L*
211 C*
L*
H
212 C *
L*
H
221 I>»
B»
F*
L*
222 D*
B*
F*
L*
231 L*
J
K
232 L*
J
K-
241 P
242 P
~~ ~~ ~ : Observed Fibrs Density (fjmx?)
AIA
>3:1 >5:1 >10:1
247 220 173263 220 173
165 155 135197 185 166
268 219 138130 103 62
420 273 187403 293 197463 442 389407 387 370
341 265 155254 187 107
176 46 10172 68 28
558 515 464
157 152 137164 157 103
290 90 44198 68 24
321 290 237
317 283 192208 185 119
154 144 2798 69 25
108 95 64124 105 54
133 117 89145 124 90
525 497 439536 536 505
560 469 83663 594 H2460 4H 288486 436 290
867 743 596743 673 546
575 499 383573 479 397
345 327 254358 321 249
129 112 34125 94 38520 489 440528 512 418
480 407 301362 311 255239 200 55192 136 55540 513 455617 587 502
307 295 187273 268 103
175 162 99164 154 78
CHS - Modified
>3:1 ?5:1 ?10:1
252 225 175268 222 175
192 183 162185 174 158
175 228 151129 102 62
420 283 187403 293 197463 440 393417 391 375360 284 173240 193 113
208 62 10194 84 40
577 538 487212 199 186170 160 126
346 130 62272 128 82
350 321 268
358 327 253264 243 175
227 200 25165 UO 25113 100 68125 106 56
140 125 89157 132 96
546 518 460540 540 509
1006 896 1191065 985 267500 454 326520 470 316
906 789 650811 741 624
590 5U 404585 491 409
361 342 270361 324 253
143 • 120 38135 95 31
707 665 612753 738 562
503 431 317365 314 258243 186 80197 139 47580 563 506862 853 759
282 242 208235 203 184
182 154 127179 153 144
CRS
>3:1 >5:1 >10:1
283 253 190287 233 183218 209 185206 194 178296 248 168131 104 62
423 293 197417 300 207
502 479 432474 446 424
376 300 183248 201 122
264 76 16228 112 52
605 566 515190 180 169219 208 164
456 208 100356 192 124
370 338 285
292 265 ' 199246 236 173
242 215 35188 158 35
129 '114 82141 120 60
171 153 108190 162 120
569 541 483544 544 513
1100 1031 1121173 1081 338556 512 372584 528 364
1076 941 783973 895 771
625 549 430597 503 421
373 355 282363 325 254
139 111 39106 79 36
573 556 506752 710 621
533 460 342365 314 258275 227 73253 196 69802 770 7U996 939 814
405 378 356255 232 209
222 208 193250 236 229
LOCAL
73:1 >5:1 >IO:1
250 223 177272 233 183191 182 160209 197 170
420 283 187403 293 197500 475 421454 431 412
182 46 10184 68 28
342 104 48234 72 28
165 152 25104 71 25114 96 64128 104 54
134 118 90146 124 90
585 471 83706 610 154492 422 290528 440 290
916 771 610783 . 696 560
104 85 22108 80 24
637 585 475528 473 402
210 149 48205 144 57
1019 948 761680 653 564
See footnotes on Sheet 1.
TABLE 3Sheet 2
25,
TABLE } ' . < ' "
Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Textile Chrysotilo
Sample No.
Lab . Code
301 B*
L«
a
K.
302 B*
L*
H
K
31 1 M
312 K
321 N
322 V
331 P
332- p
341 Q
342 Q
Observed Fibre Density (f/om2)
AIA
>3:1 >5:1 >10:1
148 96 66162 100 76
565 538 479853 822 794
146 146 115164 162 119
250 243 222226 222 195
368 230 152416 246 172
630 567 462453 363 297423 410 350402 369 31 1
990 951 793697 634 507
406 398 301356 346 244
45 45 3754 49 41
339 255 163307 231 139
133 124 102132 107 83
120 118 94115 109 89
338 311 266376 283 250
83 80 6871 70 44
239 236 199164 159 122
CRS - Modified
>3:1 >5:1 >10:1
146 94 68166 104 60
584 557 498857 826 798
164 158 132164 157 117302 290 260355 345 305
368 230 156438 266 184
691 627 511458 368 302
373 360 317460 436 382
1190 1073 879985 975 862
427 417 310430 418 295
55 55 4358 54 45
384 359 225343 274 1 61
171 145 117131 111 87
131 124 113143 123 106
339 31 1 285311 289 265
80 78 5982 82 68
199 199 184182 182 157
CRS
>3:1 >5:1 >10:1
160 108 72220 132 100603 581 522861 830 802
185 181 146200 197 163
424 407 372387 384 349
496 320 216540 332 232
738 674 558467 377 310
437 423 361571 558 487
1272 1201 10341232 1195 1096
535 530 428473 464 332
56 56 5752 50 41
390 282 180406 302 210
194 169 122184 157 133
118 112 108101 99 94
326 306 288349 334 324
164 162 12788 82 71
219 208 174244 239 200
LOCAL
>3:1 >5:1 >10:1
154 98 68166 100 76
279 264 210262 236 205
380 238 156432 254 180
1227 1146 8921207 1139 935
489441
210227
10066
156168
See footnotes on Sheet 1.
TABLE 3
Sheet 3
26.
TABLE 3 . .
Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Anbestos Cement
Sample .No.
tab. Code
401 B*
K
402 B*
K
411 L*
K
412 I,
H
421 M
422 M
423. H
424 H
425 M
431 P
432 p
441 Q
451 Q
452 Q
Observed Fibre Density (f/nm )
AIA
>3:1 >5:1 »0:1
164 142 86182 158 102
60 60 5357 53 53
92 74 4668 58 38
100 86 8376 69 66
1019 861 826929 886 861
39 38 3746 46 45
818 801 788
78 76 7362 62 56
138 133 117126 118 101
36 30 2050 43 27
22 19 1346 39 25
68 64 4380 77 54
30 18 1027 18 8
116 110 77139 128 100
405 386 288346 342 237
218 205 149129 117 85
66 59 4452 48 40
26 22 1636 34 22
CHS - Modified
>3:1 >5:1 >10:1
164 146 96182 158 102
145 U3 131122 116 111
92 74 4872 58 38
271 260 243198 195 191
1019 861 826937 895 869
66 65 6248 46 42
844 827 814
132 132 125104 104 96
219 217 196186 177 154
71 57 4359 51 41
54 50 3357 54 42
107 98 79101 94 78
47 38 2939 32 21
158 154 148171 159 H3
392 380 370368 363 343
168 ' 165 120156 148 114
87 85 5573 73 51
44 41 2548 45 32
CRS
;>3:1 >5:1 >10:1
248 220 136244 212 136221 210 203217 210 186
120 96 64108 88 60
266 266 248234 224 214
1026 869 834988 946 920
36 36 3664 61 55
878 861 848
171 167 161136 134 120
248 243 214227 212 193
80 71 5084 71 54
51 47 2855 48 38
104 97 71134 125 101
50 41 3466 56 33
159 155 145155 H9 146
526 518 497535 525 515
250 243 179179 165 94
104 97 7292 88 57
45 39 2747 42 33
LOCAL
>3t1 >5:1 >10:1
170 148 90182 158 102
157 148 136153 141 119
92 74 4672 58 38
243 240 236. 207 207 197
228 220 171219 209 178
78 69 5580 71 56
57 51 2955 48 32
116 106 84102 98 74
57 47 4243 32 22
163133
5364
4533
TABLE 3
See footnotes on Sheet 1.
Sheet 4
27«
TABLE 3
Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSmnnlp 1'vnp - tf.-trioua
Sample TypeSample No.+
Lab . Code
FrictionMaterials
501 B*
502 B»
5" • H .
K
512 ^
K
521 „
522 H
531 s
532 S
541 s
542 s
inavOationRemoval
601 I»
H
611 I*
621 K
Amosite701 H
702 H
Other
801 H
Observed Fibre Density (f/mm^)
AIA
>3:1 >5:1 >10:1
208 112 70224 1H 72
76 52 1694 53 20
59 57 5364 58 46
162 155 131195 191 164
389 370 352362 349 340536 517 468601 582 522
179 171 138176 159 139
316 285 232292 292 279
176 167 154190 172 140
40 32 2152 47 39
74 74 6282 72 59
210 191 169263 230 194
292 285 278280 277 274122 122 112119 117 87
713 671 618784 704 651
1400 1400 13171931 1879 1707
105 101 8994 94 83
596 591 567608 602 579
103 67 2099 57 22
CRS - Modified
>3:1 >5:1 >10:1
216 116 70224 114 72
76 52 16100 64 22
136 134 120109 105 82
195 179 H3212 209 178
482 463 446396 383 373792 748 666741 708 668
227 220 211236 227 209
500 477 444349 342 330
354 346 240332 329 326
255 255 247237 232 1 97
878 836 783855 778 707
1277 1239 11561272 1237 1213
139 139 135132 • 129 123
739 739 739637 637 637
121 85 38120 63 25
CRS
>3:1 >5:1 >10:1
260 140 92268 136 88
96 64 24140 96 32
127 125 113131 129 97
245 217 190197 193 162
578 558 541429 413 404
1189 1118 987996 967 862
252 234 213346 327 294
71 3 688 669655 619 601
—
415 406 400397 394 391320 317 307298 297 269
1041 996 940982 899 822
1161 1149 11152069 1017 1879
171 169 164130 130 124
822 822 822949 949 949
148 106 47158 102 41
LOCAL
^3:1 >5:1 >10:1
212 116 70230 114 72
80 52 1694 58 20
.
167 166 122188 181 172
499 480 462447 431 421
1099 1034 862803 760 662
175 152 130207 185 161
37 29 2247 39 30
75 62 56102 93 82
232 198 180239 215 186
394 386 380398 395 392
979 934 881970 891 837
1359 1333 12401473 1437 1207
.
See footnotes on Sheet 1,
TABLE 3Sheet 5
§t-1ts
TABLE 4
Effects of Aspect Ratio Changes on count level*
._\ -••Sample Type
Mining
Milling
Asbestos Cement
Textile Chrysotile
Friction Material
Others (insulation,
Amosite)
Number ofSamples
10
10
14
10
10
6
a*100
100
100
100
100
100
AIA
74
84
90
8987
92
CRS-Mod.
42
56
71
7172
80
100
100
100
100
100
100
74
84
9190
87
93
4460
777472
84
100100
100
100
100
100
CRS
75
86
93
9086
94
>10,1
4561767572
85
Mean 100 86 65 100 86 68 100 87 69
(V)CD
* Arithmetic means of counts made by different laboratories relative tothe >3s1 aspect ratio counts.
Cdtr1M\J\
TABLE 5
Relative Levels -of Count by Different Counting Rule Packages'*
Sample Type
Mining
Milling
Asbestos Cement
Textile Chrysotile
Friction Material
Others (insulation,
Amosite)
Mean
Number of
Samples
10
10
U
10
10
6
Aspect Ratio >*>:'
AIA
100
100
100
100
100
100
100
CRS-Mbd.
127112
146
109130
127
125
CRS
141
124
175125165
147
146
I
Local
117107156
121
112
118
122
Aspect Ratio >5*1
AIA
748490
8987
92
86
CRS-Mod.
92 '
95
13799116
118
110
CRS
106
107
163112
142
138
128
Aspect Ratio >10:1
AIA
4256
71
7172
80
65
CRS-Mod.
56
6711281
94
107
86
CRS
63
76
133
94119
125
102
rovo
* Arithmetic means of counts made by different laboratories relative tothe AIA (>3:1) counts.
H-<m
3 MH- H,
H-OP d-
0>J
w aE 93
*d CQ
<D rou o_ 201
1 2- 10CHO'H-CD O
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Sample No
DAY
LABORATORY
8,
32.
1200-
^E 1000
I
CO
A
r 800-
ena:o
600-UJQ
UJCCmLL
400-
200-
1 - MINING2 - MILLING3 - TEXTILE CHRYSOTILEU - ASBESTOS CEMENT5 - FRICTION MATERIALS6- INSULATION REMOVAL7- AMOSITEX- CLUSTER OF POINTS
1:1 RELATIONSHIP
200 400 600 800FIBRE DENSITY -AlA (A.R>3:1) f/mm2
Pig. 2 Comparison of fibre densities evaluated using the modifiedCRS (AR>3:1) and AIA (A.R. >3:1) rules
FIGURE 2
33.
UOOH
1200-
(N
I 1000
inAoL
QO
toccO
CozUJQ
LUCC00
800
600-
400-
200
1 - MINING
2 - MILLING3 - TEXTILE CHRYSOTILEt* - ASBESTOS CEMENT5 - FRICTION MATERIALS6 - INSULATION REMOVAL7 - AMOSITE
X - CLUSTER OF POINTS
2 3
0
1:1 RELATIONSHIP
200 400 600
FIBRE DENSITY- AIA (A.R.>3:11
800
Pig. 3 Comparison of fibre densities evaluation using the modified CRS
( A . R . > 5 : 1 ) and AIA (A.R. >3:1) rules
FIGURE 3
34.
1200-
& INDICATES AIA METHOD (A.R.>3:1) USED AS LOCAL RULES
a INDICATES CRS METHOD (A.R.>3:1)
A INDICATES OTHER METHOD USED LOCALLY
@—>
/1:1 RELATIONSHIP
200 400 600FIBRE DENSITY-LOCAL RULES (A.R>3:1) f/mm2
Pig* 4 Relationship between fibre densities obtained using the modifiedCRS (A.R. >5:1) and local (A.R. >3:1) rules
FIGURE 4
1200-
1000-
CM
.1
. - 800-riA
b 600 H.
UJQ
LLlCCmLL
400-
200-
35.
INDICATES AIA METHOD (A.R.>3:1) USED AS LOCAL RULES
INDICATES CRS METHOD (A.R>3:1)INDCATES OTHER METHOD USED LOCALLY
1:1 RELATIONSHIP
200 400 600FIBRE DENSITY-LOCAL RULES (A.R>3:1) f/mm^
Fig. 5 Relationship between fibre densities obtained using theAIA (A.R. >3:1) and local (A.R. >3:1) rules
0 — >
FIGURE 5
36.
1 INDICATES COUNTS ON DAT 1
SAMPLE NO.
LABORATORY
25-
<
20
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H-
1-2-
1-0 •1 w
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5 3R
Fig. 6a Comparison of fibre densities obtained from milling-samplesby use of modified - CRS and AIA rules at aspect ratio >3:1illustrating day-to-day and between-sample variations withinlaboratori-es.
FIGURE
37.
ACC
Aof
10CEO
to
SLL
o
*
2-5 -
<
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V8 -
1-6 -
1-4 -
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Fig. 6b Comparison of fibre densities obtained from milling samples by useof modified - CRS and ASIA rules a aspect ratio >3:1 illustratingday-to-day and between-laboratory variations within samples.
FIGURE 6B
38.
APPENDIX 1
List of Participating Laboratories
Europe
Asbest-Institut f-ur Arbeits4,inxL' Umweltschutz e.V., Neuss, W. Germany.
IMG-TNO, Delft, The Netherlands.
IMS, Nancy, France.
Institute of Occupational Medicine, Edinburgh, Scotland, U.K.
Institute Superiore Di Santa, Rome, Italy.
Laboratorium voor Industriele Toxicologie, Ministerie van Tewerkstellingen Arbeid, Brussels, Belgium.
TEA Industrial Products Ltd., Rochdale, Lancashire, England, U.K.
Canada
Carey Canada Inc., Quebec,
Johns - Manville Canada Ltd., Quebec.
Lac d'Amiante du Quebec Ltee, Quebec.
Les Mines d'Amiante Bell Ltee, Quebec.
Societe Asbestos Limitee, Thetford Mines, Quebec.
Institut de Recherche en Sante' et en Securite du Travail du Quebec(IRSST), Montreal.
Institut de Recherche et de Developpement sur I'Amiante (iRDA),University of Sherbrooke, Quebec.
Health and Welfare Canada, Ottawa.
Labour Canada, Ottawa.
Alberta Workers' Health, Safety and Compensation, Edmonton.
Ontario Research Foundation, Dept. of Materials Chemistry,Sheridan Park, Mississauga.
Dept. of Energy, Mines and Resources, Canada Centre for Mineral andEnergy Technology (CANMET), Elliot Lake, Ontario.
A2(1)
APPENDIX 2
Wbrkplan for determining the effects of various
counting rules on counting level
The purpose of stage 1 is to determine the relative counting levels
obtained using a variety of counting rules. Within the experimental
design, the results should give an estimation of the variance from:
- methods
- fibre density
- dust sources
- aspect ratio
- duplicate counting
A minimum number of ten laboratories should participate. However,
as many laboratories as possible, with different experience, should
be encouraged to take part.
It is expected that the samples selected by the laboratories for
counting will cover:
- mining
- milling
- asbestos cement
- brake lining
- textile
- insulation removal
Slides
A pair of slides is defined as two slides from their stock with the
following fibre densities:
20-40 fields/100 fibres
70-100 fields/100 fibres
Each participating laboratory selects pairs of slides from 1-4
different types of dust sources. The pairs of slides are required
to determine density effects. Single samples will only be included
in effect on counting level.
A2(2)
Counter
•(All count's were performed by one countei; in each laboratory.
List of Counting Rules
1. AIA
2. CRS
3. Mbdified-CRS
4. Local method, i.e. that is routinely used at the
laboratory (to be described by laboratory)
Counting Procedure
a. Each slide is counted once on two separate days.
Day 1 2 (NB Day 1 and Day 2
Slide 1 Slide 2 need not be
p.m. Slide 2 Slide 1 consecutive)
b. The slides are to be counted in succession according to
counting rules 1, 2, .. N. When counting the slides the
second time the counting rules are applied in reverse order.
Day 1 Day 2
AIA (3) LOCAL
CRS (3) MDD-CRS (3)
MDD-CRS (3) CRS (3)
LOCAL AIA (3)
AIA (3) represents application of the three different aspect
ratios using the AIA rules. Identify separately
those fibres in the same field of view with A.R. >10:1,
>5s1 and >3s1 and record the numbers of such fibices on
the proforma. Continue until 100 fibres with >5:1
aspect ratio are counted or 100 fields (minimum 20
fields).
Similarly with CRS (3) and MDD-CRS (3).
Local rules only require application of that laboratory's
normal aspect ratio (probably >3s1).
A2(3)
Record AIA (j results on first form
" CRS (5) results on second form
" MDD-CRS (3) results on third form
Local rule results on fourth form
(in >J:1 row) .
for each
slide
Microscope Calibration
In particular the test slides developed by HSE (lines) and AIA (latex
spheres) must be used by each laboratory.
Retention of Samples
The slides should be kept for possible further investigations.
A3(1)
APPENDIX 3
Description of Counting Rules
AIA
Rejection of Fields
Modified-CRS CRS
If more than one-eighth of the graticule area contains an agglomerate
of fibres and/or dust, reject the field and select another.
Always record such occurences.
Definition of Fibre
Each object with a maximum diameter less than 3 urn, maximum length
greater than 5 urn. and length:diameter ratio greater than A shall
be counted as a fibre. Three values of A were considered, viz.
3:1, 5:1 and 10:1.
c. Definition of "Within Graticule Area"
A fibre with both ends within the graticule
area shall be counted as one fibre; a
fibre with only one end within the area
shall count as a half.
d. "Split" and Grouped Fibres
Split fibres are
counted as one fibre
if they meet the
definition in b.
The diameter of a
split fibre is
measured across the
compact part of the
fibre, not across
the split part.
Grouped fibres are
counted individually
where individual
fibres can be
di stingui shed.
Where/
Ends of components
of split fibres or
groups of fibres
shall be counted
provided the
component meets the
definition in b,
and the end being
counted lies within
the graticule area,
and the end is
visibly free. Each
visibly free end
shall count as half
a fibre. If the
number/
A fibre with the
'lowest point' within
the graticule area is
counted as one fibre.
Each component~of a
split fibre or group
of fibres shall count
as one fibre provided
that the component
meets the definition
in b and its lowest
point is within the
graticule area, up to
a maximum of eight
fibres. If the
components cannot be
clearly distinguished,
that group or split
fibre shall count as
eight/
A3(2)
Modified-CRS
number of these
ends exceeds ten,
the group or split
fibre shall count
as five fibres.
AIA
Where they cannot
be distinguished as
individual fibres
they are counted as
one fibre if the
bundle as a whole
meets the definition
in b. Occasionally
groups of fibres are
seen as an indeter-
minate number of
fibre entranglements
which appear to
originate from the
same fibrous bundle.
These should not be
counted as fibres.
e. Fibres in Contact with Other Particles
Fibres appearing to
touch a particle are
counted as one fibre
if they meet the
definition in b and
the diameter of the
particle is less than
three micrometres.
Otherwise they are
not counted.
The visibly free
ends of fibres
defined in b which
appear to be
attached to non-
fibrous particles
shall be counted
whatever the size
of the particle.
Each visibly-free
and shall count as r
half a fibre.
Only ends lying
inside the
graticule area shall
be counted.
CRS
eight fibres.
(The simplest split
fibre comprises two
components, viz. a
main trunk and
branch which are
resolved by an
assessment of
continuity. Grouped
fibres are resolved
similarly, as are
fibres in contact
with particles).
A fibre as defined
in b and c which
appears to be
attached to a non-
fibrous particle
shall be counted
whatever the size
of the particle.
A3(3)
AIA Mbdif ied-CRS .. CRS
f. Number to be Counted
Enough graticule areas must be included to give a total fibre
count of 100. A minimum of 20 graticule areas must be includedf ^> even if more than 100 fibres are counted. It is not necessary
to include more than 100 graticule areas.
APPENDIX 4
Differences occurring between laboratories in
their implementation of the planned programme
Laboratories A-C, I and L applied all counting rule packages to the
same fields of view.
Laboratories D, E, P and H generally evaluated 100 fields, irrespective
of fibre density. Laboratories E and P additionally evaluated 200 or
400 fields on some low density samples.
Laboratory D evaluated two sample pairs; one pair was evaluated by
one observer using one microscope, the second pair being evaluated
by a colleague using a different microscope.
Laboratory N. The BSJ625 graticule was used for evaluations with
this laboratory's local procedures (at only >5*1 aspect ratio).
Counts with the other procedures were made using the Walton-Beckett
graticule.
Laboratory S. Samples were evaluated for the three aspect ratios
under consideration only using this laboratory1s local method and the
AIA method. The Walton-Beckett graticule was used with the AIA rules
(at all aspect ratios) and the laboratory's routine graticule with
its local rules (again at all aspect ratios).
Laboratory T. One microscopist examined each slide field by field,
measured the fibres and recorded each field on a card with the
graticule outline. Subsequently, that microscopist and a colleague
independently evaluated the count from the card.
Some laboratories applied their local rules at all three aspect
ratios. (see Table 2)
Some samples in the study were evaluated by more than one laboratory,
(see Table 3)
Some samples had fibre densities outside the specified range and in
some cases the difference in density between samples within a pair
were small.
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