Agnes Brokerhof, Netherlands Institute for Cultural Heritage (ICN)

FOREWORD

The first IAP meeting in Glasgow in 1998 was a great success and the enthusiasm of the participants has proved to be not just a fling, but a serious commitment to research and finding practical solutions for the problems related with indoor air pollution in museums. The initiative to have the 1998 meeting resulted in setting up a working group and the momentum that was gained has been consolidated by this second meeting in 1999. Again, in an informal, yet serious, atmosphere the developments in research into indoor air pollution and conservation were discussed.

Indoor air pollution is a topic that is increasingly getting attention. Where temperature, relative humidity and light have long been the major concern in preventive conservation, indoor air pollution has now become another recognized actor on the scene. This was obvious at the 12^th ICOM-CC meeting in Lyon, a week after the IAP meeting. Quite a few of the papers presented in the Preventive Conservation session dealt with indoor air pollution and the discussions focussed on the relationship between concentration, dose, exposure and damage. The arguments that are raised when studying the effects of light exposure on sensitive materials also apply for indoor air pollution. The so called '50 lux problem' has an equivalent in air pollutants. Now that the world has accepted the 50 lux standard we are beginning to agree that the maximum exposure should be expressed in luxhours. Before perhaps setting off on the wrong track by defining 'no observable effect levels', maximum pollutant concentrations allowed in museum air, we want to be certain that we understand the relationship between exposure and damage. If one of the results from the working group meetings is that we arrive at a common standard for pollutant exposure, then we have achieved something worthwhile.

It was an honour for the Netherlands Institute for Cultural Heritage to host the second meeting in Amsterdam. For two days there was a special air in the house, not polluted at all, rather thrilled and mixed with the smell of Mario's cooking. It is encouraging to see how a group of motivated people manage to get together each year, without sponsoring, just thriving on a shared interest. Although there is another thriving force behind the working group activities: the organizer of the meeting, who did a wonderful job, like she did last year. A special word of thanks to Lorraine Gibson!

These abstracts again give an idea of what the working group is about, it is a refresher for those who attended the meeting and for everyone who was unable to be in Amsterdam it may be an incentive to come to Oxford in 2000. See you there!

Lorraine Gibson, Netherlands Institute for Cultural Heritage (ICN)

INTRODUCTION

Following the international symposium on 'Indoor Air Pollution: Detection and Mitigation of Carbonyls' held at Strathclyde University in June 1998, a second symposium was organised by the Netherlands Institute for Cultural Heritage on 26 and 27 August 1999. The symposium was run by the Indoor Air Pollution Working Group (IAP), which was initiated at the 1998 meeting by the University of Strathclyde, the Netherlands Institute for Cultural Heritage, The Getty Conservation Institute, The Canadian Conservation Institute and Oxford Brookes University.

The two day programme focussed on an integrated approach to indoor air pollution. As such, the programme included presentations from the working group members on the holistic approach to pollution management and did not only outline the problems encountered, but reviewed air sampling, materials testing and mitigation methodologies currently implemented in the museum environment.

The presentations and discussion sessions concentrated on four topics.

1. Air Sampling Techniques: where the usefulness of a universal sampling operating protocol for acetic acid, formic acid and formaldehyde vapours in museum air, and the value and limitations of simple test methods were dealt with.

2. Understanding Pollution - Artefact Interactions: which focussed on the use of 'threshold' values, or 'no observable effect levels' and the understanding of the interaction between pollutants and artefacts with respect to concentration, dose, and material type. Development of a central database that will be used to collate information on measured concentrations and observed damage was further discussed.

3. Materials Testing: which focussed on the efficacy and drawbacks of tests currently used, and tried to determine whether a more applicable international quantitative standard is necessary, how it could be developed and what form it should take. Also the development of an international database to collate results of previous, and future, material testing experiments that have been performed by various museums and institutes was raised again.

4. Mitigation of Indoor-Generated Pollutants: where pros and cons of the different types of sorbents currently used, and possible new sorbents designed to target the more reactive, problematic, indoor generated pollutants such as acetic acid, formic acid and formaldehyde were discussed, as well as drawing up guidelines for application of available sorbents.

Agnes Brokerhof, Netherlands Institute for Cultural Heritage (ICN)

AIMS AND SUMMARY OF CONCLUSIONS

AIMS

The primary objectives of this year's meeting were to exchange information and discuss the results of current research on indoor air pollution related problems. Specifically, our main aims were to (i) discuss standard protocols for air sampling and materials testing in the museum environment (ii) better understand the correlation between pollutant concentration or dose and artefact damage, and (iii) discuss and generate development of mitigation methods.

SUMMARY OF CONCLUSIONS

1. Air Sampling Techniques

The various laboratories that perform air sampling and analyses for museums, often use the same type of sampler but follow their own sampling and analysis protocol. There is a general concern among users that different placement, and exposure times, may give rise to different measurements. It is suggested, therefore, that these laboratories compare their protocols, identify differences, discuss the rationale behind choices and develop a common protocol.

Attention should be paid to issues such as: exposure time, opening and closing of display case, re-establishment of equilibrium, thermal effects and laminar flows inside the case, distance to source, and the influence of RH. Consideration should also be given to the importance of information obtained from time-weighted average measurements. Would sensors providing real time data, such as the Purafil 'On Guard' monitor or IR gas cells, be moreappropriate? More study into the possible application of these principles is needed.

2. Understanding Pollution - Artefact Interactions

When providing air analysis as a service to museums, it is not sufficient to simply supply a list of 'numbers' without further interpretation, or advice, by the analyst to place the measured concentrations in context. At present, the analyst draws on his/her own experience to compare the results with their knowledge of previous sampling results and laboratory experiments. This of course, is a subjective interpretation, often not based on validated information, but on an extrapolation of scientific data. After sampling, one is often asked to provide standards, however, there is not enough data yet to define 'no observable effect levels'. Moreover, as is the case with light exposure, defining concentrations (intensities) may be too limited an approach and instead, a maximum dose or flux (total exposure) should be defined. The values obtained should also be related to the sensitivity of materials in the polluted environment.

The participants agreed to use Jean Tétreault's table of pollutant specifications as a starting point to further discuss the feasibility of setting standards for air pollutants. The first step will involve discussions between analysts currently involved in air sampling who will be asked to explain how they interpret their sampling results, and to justify their subsequent conclusions and advice. The hope is that a consensus of opinion will be established with respect to pollution levels and material damage. As the group collectively gains more experience in the laboratory and in phenomenological studies, the values will continue to be discussed and refined within the confines of the group until a clearer understanding of pollutant-artefact interaction is achieved. At that time (which may be years rather than months) values based on scientific data can be proposed to the conservation world without the risk of having to rectify them shortly afterwards.

The Getty Conservation Centre is willing to fund the construction of a database which will be used to compile sampling data from field and laboratory measurements to date. The aim is to gain insight into values commonly measured in museums, and to explore relationships between exposure and damage in real life situations as well as laboratory studies, of which more need to be carried out.

Another question is what happens when we see corrosion? Is what we see actually representative of what happens? How does corrosion, or crystallisation, take place? Is the formation of corrosion dependent on the probability of nucleation or on the rate of growth after nucleation and what is the relationship with pollutant concentration in these two cases?

Research into the relationship between concentration and damage might well be funded by the European Community. The network for cooperation already exists in the working group.

3. Materials Testing

There are four types of materials tests commonly used:

A. Qualitative Total Corrosivity: tests such as the Oddy test and its various adaptations, which give a good general impression of the suitability of materials for use in museums. These tests are useful pre-construction tests but generally require a long time and it is difficult to compare results from one test with others.

B. Qualitative Specific Corrosivity: tests such as silver coupons, which give a real time indication of the risk in display cases; when using materials that are more sensitive to a specific pollutant than the objects on display, they can function well as early warning system on site.

C. Quantitative Total Corrosivity: gravimetric detection systems such as the Purafil 'On Guard' monitor which has a certain resistance which corresponds to the thickness of the corrosion layer on the exposed metal sensor. The monitors can be used either on site as early warning system, or in pre-construction tests. The problem is that the museum community has little to no experience with these types of monitor, let alone knows how to interpret the results.

D. Quantitative Specific Corrosivity: tests which measure emission of specific gases. Useful for pre-construction and on site tests. These tests are much faster than "Oddy tests" but we still need to find out which parameters give the best insight in the properties which make materials suitable for museum use or not.

Meanwhile the museum community needs lists of available, tested, materials that are suitable for use. And if they want to do their own tests they need protocols for quick, simple yet reliable tests. Existing lists of recommended materials should be combined and published. Easy guidelines for uniform test methods should be published so that the recommended materials list can be expanded with new results which meet the standards of testing.

Kath Eremin will propose a format for the materials list based on the experience of the National Museum of Scotland. The group will comment so that the modified version can be discussed at the 2000 meeting of the working group.

4. Dissemination of information

To raise awareness for indoor air pollution problems in conservation the discussions in the working group should be disseminated. This is achieved by publishing the postprints with abstracts in hard copy to participants and on request. Digital versions of the postprints are available from the IAP website, http://iaq.dk/iap.htm.