Detecting asbestos fibers

What kind of equipment is needed to detect asbestos fibers?
I scraped some odd looking grey dust from out basement, put it in a plastic bag
and looked it under a microscope (40x). The particles looked round and were mixed size. Nothing looked like thin needles. Then I dug up an old chemistry set where (lucky me) I found in a sealed plastic bag some asbestos (a heating pad). I crumbled the stuff inside the bag and took a look at it under the microsope (through the plastic). The particles in this sample looked like real thin needles this time, real small even through the microscope.
I thought you need at least 100x microscope and a polarizing lens of sorts.
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If the particles look round, they are probably NOT asbestos. However, there is a small possibility that the particles are clumps of fibers. A higher magnification would help to resolve that question.
Keep in mind that the WORST size range for asbestos dust (in other words, the most dangerous size) is 5 microns to 10 microns. A 100X microscope would have a hard time resolving individual fibers in that size range. EPA uses electron microscopy to look at these fibers.

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What kind of magnification is the bare minimum? A number of sites mention 100x.
snipped-for-privacy@hotmail.com (Quitten McKrappen) wrote:

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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, K๖hler 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 community heating with fuels), from chrysotile-like organic fibres (cellulose=kleenex), etc., etc. This is why your microscope should better be equipped with polarizers.
Sorry to say that: if you are not a well-trained expert, either you will never find asbestos (chances are that you are optimistic, or that you fear the expenses), or you will find it everywhere (if you are pessimistic or paranoiac).
J.J.
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snipped-for-privacy@ulb.ac.be (jacques jedwab) wrote:

Thanks you your comments.
I am not trying to have a second income from asbestos detection! Rest assured. If I can I'll stay away from the stuff. I am looking for a microscope and have other uses for it as well. This is more of a hobby related stuff. I don't want a toy instrument so I might just as well buy a better scope (less than $1000).
From what I gather if I look at a sample at a high magnification (say 100x -1000x) and don't see anything resempbling straight arrow needle looking fibers I can't say for sure if there is asbestos. However if I do see needle-looking fibers there's a much better chance that asbestos might be there.
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me wrote:

I suppose that you are unaware that there are more than a half a dozen minerals that qualify under the term "asbestos".
Only a few of them exhibit the needle morphology and are therefore considered dangerous.
The criterion of "needles" actually fails to detect many forms of asbestos.
Here is some information on this subject.... and you can google up a lot more.
http://www.epa.gov/swerrims/ahec/summary/presentations/day1/addison1.pdf
You are making a very good decision to not buy a "toy" microscope. It will open your eyes to a lot.
Jim
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