Nitrate

You might take a look at Z39.54-198x: Standard Practice for Storage of
Paper-Based Library and Archival Documents Section 3 (Environmental
Conditions) Subsection 3 (Air Quality) which, when you look it up, under
Table 2, "Oxides of Nitrogen" advises you to see Appendix C., where we
are told

    Oxides of nitrogen (NOx), which can act as either oxidant or acidic
    gases, can be assumed to be detrimental to records materials
    (although there is less laboratory evidence to substantiate this
    assumption than there is for the effects of sulfur dioxide) and
    recommended maximum levels have been recommended in two recent works
    (5,6).

    However, contrary to the assumption that sorption devices are
    effective for removal of SO2 are probably also effective for NOx, a
    recent study of pollutant levels inside buildings having in one case
    permanganate-impregnated activated alumina and in the other alkaline
    wash sorbent systems have shown that both systems have limited
    effectiveness in removing NOx (7).

    Thus it seems inappropriate to provide a standard for NOx levels
    until an effective means for removing this pollutant can be
    demonstrated.

Notes:
    (5): Thomson
    (6): Mathey et al.  Air Quality Criteria for Storage of Paper-based
            etc
    (7): Hughes and Myers.  Measurement of the Concentration of Sulfur
            Dioxide etc.

Or in other words, don't ask.

Also the getty has a book on ozone that might be useful as some of it
deals with nitrogen dioxide). [Cass, et al. Protection of Works of Art
from Atmospheric Ozone. Research in Conservation Number 5, 1989.  The
Getty Conservation Institute].  See especially the appendix
"Mathematical Modelling of Chemically Reactive Pollutants in Indoor Air"
(no I havent read it yet.  who has time to read?).

Or, you could phone Jim Druzik (one of the "al" in the above "et al") at
the GCI.  I think I met him once and he is very friendly.

hope this helps a little.
w

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                   Conservation DistList Instance 4:9
                  Distributed: Tuesday, August 7, 1990
                        Message Id: cdl-4-9-003
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