Fluorescent tubes and UV

I have been taking light and UV readings in the libraries and
archives where we have been placing dataloggers for 5-month periods.
Most of these institutions are lit with fluorescent tubes.  Most
also do not have UV-filtering sleeves on these tubes.  However, many
of them, the tubes that is, are located above the plastic shields
that cover the bottom of the "boxes" in which the tubes are housed.
Even so, I expected to get high UV readings below these lights. Much
to my surprise, the readings are low - around 10uM/lumen or 2-3
uM/M2.  Stefan Michalski responded that he thought that the
manufacturers of the shields put a UV inhibitor in them because they
UV was breaking down the plastic rapidly.

Can anyone confirm what I am finding?  Does anyone have any
confirmed explanation of why this is so?  If this can be confirmed,
does anyone know what the life of these shields is?  This could have
important implications for lights in libraries, archives, and
museums.

Gregor Trinkaus-Randall
Collection Management/Preservation Specialist
Massachusetts Board of Library Commissioners
648 Beacon Street
Boston, MA 02215-2070
(617) 267-9400, (800) 952-7403 (in-state)
Fax: (617) 421-9833
gtrinkaus-randall<-a t->state< . >ma< . >us

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                  Conservation DistList Instance 10:61
                 Distributed: Tuesday, January 7, 1997
                       Message Id: cdl-10-61-005
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