Re: Using microscope to test for asbestos fibers

From: jacques jedwab (jjedwab_at_ulb.ac.be)
Date: 07/19/04 

Date: 19 Jul 2004 08:12:19 GMT

Asbestos business is a serious one: one is playing with human
lives!...Downplaying the difficulty and expertise is foolish.

You need a good prep: clean glass slide, clean cover glass, immersion oil,
good dispersion of all particles and clumps.

You need a good light microscope: good adjustable light source (filament
alignment and variable intensity), double diaphragm, Köhler illumination.
Binocular viewing is best for avoiding eye strain.

You need a good 40x objective, a 10x ocular eyepiece. You can do without a
phase constrast device, but then your expertise should be at a very high
level.

You need some expertise to recognize each of the different asbestos
fibres: crocidolite, amosite, chrysotile, which look quite different.
Morbidity and regulations are widely different for the various asbestos
-types.

You need even more expertise to distinguish asbestos fibers from other
fibrous silicates (fibrous talc, wollastonite,...which are also found in
indoor households), from asbestos-looking Ca-sulfates (bassanite, gypsum,
which are widely released in the outdoors by heating with sulfurous
fuels), from chrysotile-like organic fibres (cellulose=kleenex), etc.,
etc. This is why your microscope should better be equipped with
polarizers.

J.J.

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