LEV on rotating saws and other equipment is rarely 100% effective because
the velocity of the entrained air around saw blade is high enough to
overcome the capture velocity from the extraction system. Additionally the
saw may produce very fine dust that remains airborne for a long time,
creating an exposure risk for longer than the cutting process. It is
possible to visualise the dust coming from a saw using a Tyndall Lamp, this
is a much cheaper device than pumped samplers, and would allow you to see
how changes in sawing technique produced more or less dust.
Have you considered using a wet cutting technique, which will very
effectively control dust? It may be a bit messy but it should be fairly easy
to construct a suitable device to catch the run off water and protect the
patient. Or are there powered cutters that can snip the plaster instead of
saw it?
Conversely controlling dust exposure during the mixing of the plaster may be
much easier, either by the use of a fume cupboard or by using lip extraction
at the edge of the bowl during mechanical mixing. The low velocity of dust
particles created during mixing makes them much easier to capture with LEV
systems. Once the powder is fully wetted then dust generation will stop.
Although I have not seen plaster being mixed I have observed a similar
process in a bakery and dust production ceased very quickly once the mixing
began.
Regards
Richard Brown
Occupational Hygienist
Health, Safety & Environment Division
Abu Dhabi Marine Operating Company
PO Box 303, Abu Dhabi, United Arab Emirates
Tel: +971-260-65325
Fax: +971-260-64997
-----Original Message-----
From: Glenn Raybone [mailto:[log in to unmask]]
Sent: Monday, December 02, 2002 1:52 AM
To: [log in to unmask]
Subject: Plaster dust
Hello all,
a quick question for those in the NHS. Does anyone undertake health
surveillance for those exposed to plaster dust??
I have been asked to do this but with the use of LEV by the saw it seems a
strange request. I would have thought there's more respiratory problems
when the plaster is mixed as powder dust is released into the atmosphere.
Any thoughts or ideas would be gratefully received!!
Oh and can I be the first to wish you all a Merry Christmas, a good rest
over the festive season, and a peaceful and prosperous new year.
Glenn
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