Identification of Asbestos in Bulk Samples- Training Course

Identification of Asbestos in Bulk Samples (PLM) - BOHS P401 Training Course

Course Objectives
This module provides theoretical and practical knowledge in the techniques of Asbestos sample identification using
polarised light microscopy (PLM). The module is at a proficiency level which must aim to provide the student with the
practical knowledge and skills to be able to carry out the stated work. To pass the practical assessment for this
module the candidate will normally need to have some practical experience with polarised light microscopy and or asbestos
identification.

COURSE CONTENTS
TOPIC TIME ALLOCATION
1. ASBESTOS FIBRES 5%
2. SET UP AND USE OF A POLARISED LIGHT MICROSCOPE 15%
3. ANALYSIS OF BULK SAMPLES 40%
4. PRACTICAL WORK 40%
Note: Reference is made in this syllabus to HSE guidance or other documentation. This may not
be the most up-to-date relevant publications from HSE/other sources and is intended as
guidance for candidates only.
1. ASBESTOS FIBRES (5%)
1.1 Asbestos
Describe the 6 regulated forms of asbestos in relation to the serpentine and amphibole
groups of minerals. Discuss their characteristic properties, such as flexibility, tensile
strength, combustibility, thermal conductivity and resistance to chemical attack. Describe
the effects of thermal and other forms of degradation on asbestos minerals.
1. ASBESTOS FIBRES (5%)
1.1 Asbestos
Describe the 6 regulated forms of asbestos in relation to the serpentine and amphibole
groups of minerals. Discuss their characteristic properties, such as flexibility, tensile
strength, combustibility, thermal conductivity and resistance to chemical attack. Describe
the effects of thermal and other forms of degradation on asbestos minerals.
1.2 Uses of Asbestos
Explain the physical and chemical properties of asbestos which have determined the use
to which it has been put by industry. Discuss the three types of asbestos which have
found significant commercial use (amosite, chrysotile and crocidolite) and the types of
materials they were added to. Describe the use and occurrence of the other types of
asbestos particularly as possible contaminants in other minerals.
Educational Objectives
The student must have a good knowledge of the types and forms of asbestos fibres and their
industrial
uses.
2. SET UP AND USE OF A POLARISED LIGHT MICROSCOPE (15%)
2.1 Equipment and use
Review the minimum equipment required. Discuss and demonstrate alignment of the
optics and obtaining even or Kohler illumination. Discuss and demonstrate the alignment
and use of the rotating stage, polarisers and cross-hair eyepieces, field and sub-stage
diaphragms, phase and dispersion staining objectives.
2.2 Theory
Discuss the theory of polarised light and the effects produced on crystalline and
amorphous or vitreous materials. Cover the basic physics behind colour, pleochroism,
birefringence (interference colours), sign of elongation and extinction.
2.3 Observations
Demonstrate the occurrence of colour, pleochroism, birefringence (interference colours),
sign of elongation and extinction. Discuss and demonstrate the use and effects of
refractive index oils and the use of Becke line and dispersion observations.
Educational Objectives
The student must know the theory of polarised light and the practicalities involved in setting up
and using
a polarised light microscope.
asbestos types i.e. colour, lustre, elasticity, tenacity, morphology and behaviour in water.
3. ANALYSIS OF BULK SAMPLES (40%)
3.1 Macroscopic examination
Using MDHS 77 (1) as a basis, demonstrate examination by low power stereo
microscope, including the recognition of the basic physical properties of the main
asbestos types i.e. colour, lustre, elasticity, tenacity, morphology and behaviour in water.
3.2 Sample Preparation
Explain and demonstrate the options for sample preparation to segregate the asbestos for
analysis. Using MDHS 77 (1) as a basis, demonstrate sample preparation methods to
remove matrix materials before PLM identification, including acid washing, solvent
extraction and combustion.
3.3 Polarised Light Microscopy
Examine using polarised light microscopy characteristics such as morphology, colour,
pleochroism, birefringence (interference colours), sign of elongation and extinction of
different asbestos types.
3.4 Dispersion Staining
Describe and demonstrate dispersion stain microscopy using R.I. liquids together with a
McCrone dispersion staining objective or phase contrast microscopy with polariser in
relation to the assessment of refractive indices of asbestos and other fibres.
3.5 Safety During Identification
Discuss the safety precautions required when working with asbestos and other fibres e.g.
the use of glove boxes and ventilated cabinets as well as the required precautions when
using acids during sample preparation and when handling R.I. liquids.
3.6 Quality Control
Discuss Quality Control procedures, likely detection limits, problems of cross
contamination during sampling and analysis, together with the handling of homogeneous
and heterogeneous samples. External proficiency schemes such as AIMS.
3.7 Interfering fibres and products
Describe the other types of fibres which may interfere with asbestos identification e.g.
leather swarf, skin cells, polyethylene. Problems with other products such as floor tiles.
The effects of heat on asbestos fibres.
Educational Objectives
The student must be able to describe the approved methods for analysis of bulk fibre samples
and have
an understanding of the exposure controls and quality controls required during this activity.
4. PRACTICAL WORK (40%)
Practical work must be carried out to provide the student with all practical knowledge in carrying
out the following:
microscope set-up
sample preparation
PLM typing of unknown samples
Identification of asbestos using polarised light dispersion staining techniques.
COURSE LENGTH
It is envisaged this course would be run over 2 days with a further ½ day for the examination and
assessment.
REFERENCES
(1) HSE Guidance MDHS 77 (1994) Asbestos in Bulk Materials Sampling and Identification by
Polarised Light Microscopy (PLM)
COURSE EXAMINATION/ASSESSMENT
The students would be assessed as follows:
\uDBC0\uDC00 A 45 minutes MCQ BOHS examination (25 questions).
A practical assessment, which involves the identification of unknown samples derived from
the AIMs scheme and supplied by BOHS as follows:
PRACTICAL ASSESSMENT - ASBESTOS IDENTIFICATION
Assessment must include:
Identification of 6 unknown samplesA full marking schedule based on HSL scoring is used
Successful completion of the above will lead to a:
'PROFICIENCY CERTIFICATE' in IDENTIFICATION OF ASBESTOS IN BULK SAMPLES (PLM)