Determining source of odour

For several months we have been experiencing strange odours in a
Conservation lab office, which then gradually make their way into
the lab itself.  We do not know what these odours are or where they
are coming from, although they are frequently described as the smell
of a bus depot when lots of engines are running.  (We are located
below a garage and loading lock but often when the odours occur
there has been no vehicle in the vicinity.)  The odours are
irritating, to say the least.  They occur several times a week.
Sometimes a strong smell seems to waft in from somewhere and takes
1/2 hour or more to disperse.  Often, a slightly "off" smell lingers
all day.

We have been keeping a log of the incidents of odours in hopes that
this will help our Building Management personnel determine the
source of the problem.  Despite their efforts, the mystery remains
unsolved.  We have had a home carbon monoxide monitor in the office
for about a month and it has registered no carbon monoxide.  We have
had the ducts checked and know that they are clean and that the air
pressure is balanced as intended. There is a high rate of air
exchange here--in fact, several years ago we had an environmental
company look at various areas of the building and they found that we
had unusually good air.  But something has changed in this
particular area and we don't know what.

A number of hypotheses has been proposed but none of them seem
logical. This area is under negative pressure so we wonder if there
could be a crack in a wall somewhere which allows outside air to be
sucked in here.  But why is that air so bad?   We are near an
elevator shaft.  Are odours whooshing down it?  But again, where do
the odours come from in the first place?

Now Building Management proposes that they start carrying out tests.
They would like to begin to systematically release a known strong
odour from various points of origin in and outside of the museum, to
see if and when the odours get to us.  If they can establish a
pathway they hope to establish a source of the odours.

Does anyone have experience in detecting the sources of odours?  Any
advice? We have talked about buying gas detection tubes which we
would deploy whenever the odour is noticed, but we have no idea what
gases we are looking for.  Does anyone know of a substance which can
be released to produce an odour without causing any harm to
collections and staff?  Is this a wacky idea?  Could it possibly
work?

Karen Potje
Head, Conservation/Preservation
Canadian Centre for Architecture
1920 Baile Street
Montreal, Quebec H3H 2S6

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                  Conservation DistList Instance 12:51
                Distributed: Tuesday, December 15, 1998
                       Message Id: cdl-12-51-023
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