Dear Bruno, Jerry, Cecily,
Thanks to all of you for your interesting comments.
As Cecily points out, also outdoor pollutants are of great concern in the indoor museum environment (I speak now from a material/object deterioration point of view, not human comfort). For example NO2 causes decay of textiles, photographs, fading of dyes, etc. Typical recommendations suggest exposure values of not more than 10 ug/m3 for NO2 in collection environments.
Buildings located in urban areas may be exposed to quite high outdoor NO2 concentrations, due to car traffic in the surrounding areas. As an example I'll use my own workplace, the National Museum of Denmark: Located in the city centre of Copenhagen, with approximately 18,000 vehicles passing just outside each working day, the average outdoor concentration of NO2 at street level is around 30-50 ug/m3 (NOx around 150 ug/m3). Peak concentrations during rush hour can be much higher (NO2: 150 ug/m3 or more).
Many historic houses, or museums in older buildings are without mechanical ventilation system, at the National Museum only selected areas (about half of the building) has HVAC. Typical indoor/outdoor concentration ratio (I/O) of NO2 for a naturally ventilated building is in the order of 0.6 - 0.8.
From measurements performed at the National Museum we have found the NO2 I/O rate in a gallery located in the non-mechanical ventilated part of the building to be 0.66. This means that the average indoor level is somewhat reduced compared to outdoors, but still well above the 10 ug/m3 recommendation.
The reason that the level is reduced at all, is probably due to surface reactions between the nitrogen oxides and the building materials in the walls, windows, etc., which the air passes over on its way into the building. Pollution removal by the fabric of the building could, if exploited right, be a big help in reducing the indoor levels. Maybe by applying this new paint type at typical entry ways for air (window frames, air grills etc.) this could help lowering the level of air pollution indoors.
- Morten
PS: For those interested in natural ventilated houses, I co-authored a conference paper last year, which, among other things, contains the I/O measurements I mention above:
Ryhl-Svendsen, Padfield, Smith, De Santis (2003): "The indoor climate in historic buildings without mechanical ventilation". Healthy Buildings 2003, Preprints: Singapore 7-11 December (Vol. 2), ISIAQ, p. 278-283.
* * * * * * * * * * * * * * * * * * * * * * *
Morten Ryhl-Svendsen
Cand.Scient.Cons
National Museum of Denmark
Conservation Dept., The Laboratory
Postbox 260, Brede, DK-2800 Kgs. Lyngby, Denmark
Phone: (+45) 33 47 35 35 Fax: (+45) 33 47 33 27
Web: http://www.natmus.dk/sw1592.asp
-----Oprindelig meddelelse-----
Fra: Cecily Grzywacz [mailto:[log in to unmask]]
Sendt: 11 February 2004 00:14
Til: [log in to unmask]
Emne: Re: Smog-busting paint
oops I forgot the not.
>>> [log in to unmask] 2/10/04 12:57:45 PM >>>
Bruno,
Yes, indoor-generated pollutants are a problem, especially the persistent organic pollutants you discuss in your first email. However, we should NOT forget that outdoor-generated pollutants also pose a risk to collections, especially those not in micro climates. NO2 and NO are still relevant pollutants in all buildings and museums. Anything that can be done to reduce or eliminate them from the museum environment is beneficial for the collection.
Regards,
Cecily
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Cecily M. Grzywacz
Scientist
Analytical Research Team
The Getty Conservation Institute
www.getty.edu/gci
1200 Getty Center Drive, Suite 700
Los Angeles, CA 90049-1684
voice: + 310 440-6260
fax: + 310 440-7711
email: [log in to unmask]
"I think scientists and artists are doing the same thing, which is exploring the world, discovering new ways of looking at the world, and using nature as inspiration." -- Scott Lesh, artist."
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>>> [log in to unmask] 2/10/04 3:22:40 AM >>>
Dear Morten,
thank you very much for this interesting information that could be usefull
in reducing outdoor airborne pollutants. However, this inovative technology
seems to be well adapted to airborne pollutants of Nitrogen-oxides (NOx)
type, wich are not specifically the type of airborne contaminant found in
Museums : aging preservative chemical residues ranging from mercury
dichloride and arseniates for the most ancients to polyaromatic chlorinated
molecules that have to be taken into account together with "usual" indoor
air contaminants such as PBDE flame retardant degradation by-products, DEHP
diethylhydrophtalates from paints and plastics, SCCP small chain
chlorinated paraffins and sometimes organotins in paints, foams and rubbers
as fungicide and preservative.
All these compounds (considering that the HgCl2 and Arseniate exposure risk
has been correctly reduced to acceptable levels in case of ancient
museological collections in natural history, anthropology, wooden objects
etc.) are persistant organic pollutants or endocrin disruptive compounds,
which, eventhough they are rather large molecular weight compounds (with low
vapor pressure at room temperature) can have fragments cleaved by oxydative
degradation (with oxygen, ozone, organic acids, nitrogen oxides) or
hydrolytic degradation (with water from relative humidity). The chemicals
formed from this degradation are necessarily of lower molecular weight and
therefore of much higher vapor pressure (more volatile). They hence may
persistantly contaminate the indoor air both by micro & nanoparticulate
matter and by molecular elements for the most volatile species.
Therefore, eventhough this new technology seem promizing for many potential
applications, specific reduction of the indoor air persistant organic
pollutants (POP's) and endocrin disruptive compounds (EDC's) can be acheived
with other methods that seem to be much more adapted to Museum IAQ concerns.
If some of the Museum IAQ discussion list participants are interested in
data on specific ways to monitor and control the breathing exposure levels
for museums and cultural heritage building staff, please ask.
Best regards,
Bruno G. Bordenave
Researcher in Botany
PhD of the Museum National d'Histoire Naturelle (Paris)
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----- Original Message -----
From: "Ryhl-Svendsen, Morten" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 09, 2004 12:59 PM
Subject: Smog-busting paint
Dear List,
In the latest issue of New Scientist (7 Feb 04) there is a story on a new
air pollution reducing type of paint. Maybe this could be useful also for
museum applications.
I have copied the text from the NS website (below)
regards
Morten ryhl-Svendsen
List-owner, IAQ.dk web master
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