Rebecca -

Have a read at two recent Commission on Preservation & Access
publications, Donald K. Sebera, _Isoperms: An Environmental
Management Tool_, June 1994, followed by James M. Reilly,
Douglas W. Nishamura, and Edward Zinn, _New Tools for
Preservation: Assessing Long-Term Environmental Effects on
Library and Archives Collections_, November 1995. I believe
that the texts of both are available at the CoOL Web site. The
address of the Commission is 1400 i6th St., NW, Suite 740,
Washington DC 20036-2217. As I have remarked elsewhere, the
"data-logger vs. hygrothermograph" debate sometimes resembles
the "latke vs. hamantash" debate, so these two publications may
not definitively resolve your quandary. But they might help.

"Hop Schweiz"