John,

    When I worked at a museum we housed an enormous collection of photo
negatives from the mid-1800s through the 1930s.  If memory serves, the
negatives had to be stored in a bomb locker because of the risk of sponaneous
ignition of the nitrogen based compounds which outgassed from the materials
over time.  Obviously, we needed to keep the collection cool, but the
overriding concern was to ventilate the larger area that the bomb lockers
were in with a spark and static free apparatus.  We may have been avoiding
the larger issue of preventing the decay of the materials for lack of
funding.  We settled for trying to make the area safer for people than for
the collection.

David J. Dauerty
To The Line Timber Frames