RE: UV protective material

["Levin, Robert" <levin@OSI.SYLVANIA.com>]

Both acrylic and polycarbonate will attenuate in the UV.  This
attenuation is a function of both wavelength and thickness and depends
on the specific type/grade of the material.  Such information can best
be obtained from the manufacturer of the plastic. 

Because there is radiation below 320 nm, the ACGIH TLV based on
S(lambda) weighted power must be considered (radiation above 320 nm is
unlikely to make a significant contribution to the S(lambda) TLV for
this type system).  For this evaluation you will need the spectral
irradiance at the exposure location.  It may be available from the
manufacturer of the light box.  Alternately, it can be estimated using
the spectral power of the lamp (from the lamp manufacturer) together
with light box characteristics.  A worst case estimate eliminates the
need to make spectral irradiance measurements in situ.  The ACGIH TLV
based on total power in the 320-400 nm band should be reviewed, but most
cases with a few low power lamps, it is difficult to approach this TLV.

Note that any attempt to use a radiometer requires that its spectral
response matches the S(lambda) function or an equivalent calibration for
the specific spectrum at the point of measurement must be known.

Robert E. Levin
Corporate Scientist
OSRAM SYLVANIA Inc..
levin@OSI.SYLVANIA.com

>----------
>From: 	George Rawls[SMTP:george@pliny.ehs.ufl.edu]
>Sent: 	Tuesday, December 02, 1997 11:16 AM
>To: 	Multiple recipients of list
>Subject: 	UV protective material
>
>I have a question from a lab and have been unable to find an answer 
>in my texts and manuals.
>
>The question: We have a UV light box which produces a 312nm 
>wavelength for viewing ethidium bromide agarose gels.  It uses 6, 15 
>watt bulbs.  We need to buy a shield and the catalog offers a 
>polycarbonate or an acrylic material.  Which is sufficient for this 
>wavelength?  Both?  Is the only difference one of strength?  
>
>I have no text which discusses materials except in a general way and 
>I view this as a chance to broaden my knowledge of UV....so if anyone 
>can answer the question(s) AND offer advice on text, I would 
>certainly appreciate it.
>
>If you don't think the list needs the info, please respond directly 
>to me.
>
>george@pliny.ehs.ufl.edu
>George Rawls
>University of Florida
>Health Physicist
>george@pliny.ehs.ufl.edu
>