IAP 2001, Presentation 8 - PART 2:


Janet Hughes and Steve Hennessy

National Gallery of Australia


Slide 1

A recent journal article mused that one day in the future, the current Director of the National Gallery of Australia, an Irishman, will look back on his time in Australia and recall one of the idiosyncrasies of the Australian arts scene, and will surely reply:
"You have to understand Australians are passionate about their air-conditioning"
Indeed this would be a reasonable prediction based on the numerous questions asked in Parliament and countless media articles written on the recent air conditioning problems of the NGA building (Ford 2000). Australians could be expected to be passionate about air conditioning in the variable climate of the national capital, Canberra which is cold (often below -5C) in winter and often over +35C in summer. Air conditioning is vital for visitor comfort and to protect the collections - but what happens when a former conservator alleges that HVAC operations & maintenance were putting the collections at risk.

This paper describes briefly the methodology and conclusions of the investigation of IAP issues at NGA and discusses the difficulties of communicating the risks to collections in the absence of comprehensive, agreed, evidence-based standards.

Slide 2

There were 2 classes of allegations concerning the NGA HVAC: Health/safety and threats to collections.

The health allegations were wide-ranging including poor standards of hygiene, inadequate training, improper handling of chemicals and lack of response to reported building problems.

This paper focusses on the theats to collections. The NGA collections cover a wide range of materials including works on paper, paintings on canvas and panels using various media, textiles modern and ancient from around the world, glass, metals and a large collection of Aboriginal & Torres Strait Islander art of diverse materials including bark, wood, feathers, leather, and other plant materials.

Slide 3

The consequences of the allegations have been 18 months of adverse TV, radio reports with many articles in the press, including some on the front page of national newspapers. Senior NGA staff were called to answer detailed questions at Senate Estimates hearings in the Australian Parliament and there were two statutory investigations by the Australian Government Occupational Health and Safety agency (Comcare), as well as an enquiry by the Commonwealth Ombudsman.

This situation caused considerable staff anxiety and disruption because of the time required to address the allegations.

In the preparing this paper we formed the impression that this media and Parliamentary interest in IAP issues in museums was unusual. This experience highlighted the problems of investigating and communicating these issues when, at the time of the investigation, there were no agreed IAP standards giving specific guidances for museums.

Slide 4

This is but one example of the media coverage in national newspapers.

The serious nature of the allegations necessitated an independent enquiry. Following discussions with the Institution of Engineers, Steve Hennessy, a mechanical engineer, was selected to conduct the enquiry to produce a comprehensive report for the NGA Director.

The enquiry commenced in June 2000 and proceeded over several months due to complex microbiological testing requirements and additional information produced during the investigation. At the initial investigation meeting with NGA staff it was apparent that health allegations could readily be dealt with by reference to comprehensive, detailed standards (eg risk-based standards for Legionella). This could not be done for allegations regarding the collections, particularly concerning the H2O2 concentrations. The investigation could not be extended for the years that would be necessary to develop such standards! NGA Conservators supported the investigation to determine whether some problems observed during collection surveys were due to HVAC or other causes.

Slide 5

The history of development of IAP standards is well known to this audience but a brief review is given here to provide some context of the approach to the NGA issues. Thomson provides longstanding standards on NOx, SO2, ozone and particulates. More recent investigations have focussed attention on the impact of carbonyl pollutants on enclosed spaces and it is excellent to have this information collated on a website thanks to Morten Ryhl-Svendsen.
Tetreault provides an excellent overview of the types of standards that should be considered:

  1. Acceptable risk concentration
  2. Background level (cf with external concentrations)
  3. Dosage (concn x time)- but problematic where deterioration is not linear with time.
  4. No-Observed Adverse Effect Level (NOAEL)- requires knowledge of concn, T, RH, time, property measured.
  5. Threshold level (reaction kinetics and thermodynamics)

Padfield provides thought-provoking comment in several papers and letters (in references) on perils of reliance on numbers at the risk of understanding the effects.
Cassar et al compared IAP in HVAC and non-HVAC buildings in London concluding that HVAC did not significantly improve control of IAP except for NOx and particulates.
The NGA case study examines role of HVAC in controlling IAP in a 'clean' city.

Slide 6

Building commenced in 1978 and it was opened in 1982. It is typical of many large modern art galleries of the period built extensively of concrete.

Lower levels have art storage, workshops, loading dock. There are two levels of galleries and top floor contains administration area including Conservation lab.

The building has a history of problems including roof membrane leakage, condensation especially in winter, dust from bush-hammered concrete. These problems have been progressively fixed over the past few years, but this has been expensive.

NGA frequently attracts media attention, being located in the maligned national capital unloved by the competing major cities of Sydney and Melbourne.

Slide 7

The HVAC system is quite complex due to needs for RH control. Being an inland city with prevailing low RH means dehumidifiers are not standard equipment, but humidifiers of varying types have been used throughout the building's history. Of the 9 AHUs in the original part of the building, 4 have spray humidifiers and 1 AHU has a steam humidifier. Filtration varies according to the type of space, being highest for spaces with works of art.

A new 1,600 m2 extension gallery has 9 additional AHUs, each with its own chillers, filters and steam humidifiers to enable close control of conditions for blockbuster exhibitions.

HVAC costs are considerable. A major building refurbishment and enhancement project costing USD 21 million over 3 yrs will include extensive work on the HVAC system.

Slide 8

The crucial issues arising from the allegations are whether H2O2 aerosols are carried from the humidifiers via the ducts to areas where works of art are displayed or stored.

H2O2 is used monthly to clean microbial growths from the humidifiers, particularly the cooling coils, as these can be expected to grow in continuously wet conditions. A biocide is used to kill the organisms and H2O2 breaks up the organic matter. A 50% solution is diluted to 1%v/v in the trough and circulated through the sprayers for 2 hours, then drained and cleaned off with pressure sprayers. The fans are turned off.

There are no museum standards available for max permitted concentration of H2O2 so the approach was to measure air movement and concentrations throughout the dosing and cleaning process. Air movement was found to be insignificant using standardised sensor measurements. Peroxide concentrations were measured in air and water samples from 2 AHUs subject to detailed testing. Test methods were colourimetric (for water) and Draeger tubes used calibrated measurements of reaction with potassium iodide.

Despite this extensive testing, those making the allegations have not been satisfied and it remains difficult to refute the allegations absolutely without evidence-based standards although it is also unrealistic to expect these could be developed without several years of research.

Slide 9

This shows the pressure spraying underway to rinse off peroxide used in the monthly cleaning of the humidifiers. Note the sprayers at left and troughs at lower left, where the peroxide solution is poured in and diluted for circulation.

Note: without the use of peroxide the cleaning process would not be as efficient in killing microorganisms in the humidifiers, ie the peroxide supplements the use of biocides. Without such cleaning there could be an enhanced risk to public health, so there is an issue of balancing concern about the use of any chemicals (especially an oxidising agent) against the assurance of public safety.

Slide 10

A lighter moment during the investigation (from Ford 2000).

Slide 11

Broad scale surveys of collections are done regularly at NGA and three significant problems were identified over recent years where the cause could possibly be due to IAP.

Fatty acid blooms on some 100 paintings could be due to the known previous problems with alkaline particulates due to the use of bush-hammered concrete walls, but instances have arisen in other paintings by the same artists due to pigment-binder interactions.

Weeping glass on some 10% of the collection stored in the building could also be due to alkaline particulates distributed by HVAC, but could also be due to unstable composition or other causes.

Silver tarnishing was another known long term problem in the Small Object Store with approx 2/3 of the silver items in this area affected. This could be due to air quality from HVAC or from the cabinets.

Slide 12

A central issue of the investigation is whether agreed risk factors are actually causing the observed problems.

Apart from the H2O2 tests, particulate measurements were made throughout the building using Grimm particle analyser.
In addition a series of alkalinity, fatty acid and greasy film tests were used to determine whether this is the cause of the fatty acid blooms in the painting store. A 'grab sampling' method using a sealed vacuum cannister with absorbents was used to collect gaseous pollutants for GC-MS analysis.

Various water samples from humidifiers were analysed, particularly 'dissolved sulphide' and 'easily released sulphide' to determine whether the HVAC is a source affecting the silver collection.

(Results are available from the authors and a paper discussing the methodology and results has been submitted for ICOM CC Rio 2002)

Slide 13

This shows air sampling undertaken in the Paintings Store, which is located on the lowest floor close to the loading dock.

Slide 14

Sampling of supply air in the Small Object Store, the room where the problems with the silver and glass items were observed during collection surveys.

Slide 15

Sampling in the silver cabinet in the Small Object Store. Note the wood and plywood construction of the cabinets, which are over 20 years old and were lacquered with Paraloid B72. The silver items are placed on archival paper.

Slide 16

There is a need to balance health requirements to effectively clean the humidifiers against the very low risk that H2O2 might cause damage below the detection limit.
Nevertheless, the high labour costs of this cleaning method are such that alternative humidification methods have been sought: an atomising system has been successfully installed in one AHU and ultrasonic methods are being considered which are easier to maintain and offer energy savings.

Gaseous pollutants complied with the existing standards except in 3 samples from the Paintings Store, Silver Cabinet and in one gallery.

Alkalinity and fatty acid results showed that alkaline particulates were not the source of the fatty acid blooms.

Failure of pressurisation control was a concern on the lower floor that is believed responsible for the high results for SO2 and greasy films. This is being addressed in ongoing upgrading of the HVAC system and further tests will identify if this has been successful. Any changes in 'gas scrubbing' efficiency will also be monitored as the old spray and steam humidifiers are replaced by ultrasonic ones.

Slide 17

The NGA HVAC system is a significant operating expense, one of many that must be considered by the Director in managing the budget. To communicate the priorities for achieving good control of IAP in museums it is necessary to be able to relate conditions in one's own institution with some form of accepted standards. Without these standards or accepted best practice guidelines it is difficult to defend one's position when challenged.
For chemicals known to cause significant damage to collections, conservators require some form of evidence-based standard, either NOAEL, although working towards threshold data would be useful. Where unusual chemicals are questioned, such as hydrogen peroxide, then perhaps comparison with background levels or some acceptable magnitude lower than OH&S standards may be the only option given that research resources required to establish standards are unlikely to ever be available.
A further concern is whether the low IAP levels required to prevent damage to collections are achievable/affordable. This drives the 'acceptable risk' approach to standards and may be suitable as an interim measure if the consequences of the risk can be defined.
Acceptance ofa best practice methodology and guidelines such as those of the Museums Association in UK would make it easier to present a case for resources to address IAP issues in museums, especially since this guide also specifically addresses energy efficiency.

Slide 18

The investigation refuted the allegations that the HVAC system was causing damage to collections.

The NGA case study provides some analytical data suggesting practical bounds for IAP in a modern air conditioned building in a 'clean' city.

The investigation focussed attention on IAP issues at a high level- suggesting both standards for maximum concentration and guidelines for approaching the problems are required to provide some measure of authority for comparing the performance of individual institutions against some form of 'best practice'.

Guides to best practice, even allowing for lack of established IAP standards will help conservators to communicate priorities for dealing with IAP issues in museums.

Slide 19


Cassar, M; Blades, N; Oreszczyn, T 1999
Air pollution levels in air-conditioned and naturally ventilated museums: a pilot study. ICOM-CC Triennial Conference, Lyon 29 August- 3 September 1999, 31-37

Ford, B. 2000
The Great NGA Air Con- Unpublished CD ROM compilation of Hansard, letters, media articles and images sent to NGA staff.

Hennessy, S. 2000
Investigation of Issues Related to the Operation and Maintenance of the Air Conditioning Systems at the National Gallery of Australia. Unpublished report by AHA Management Pty Ltd to National Gallery of Australia

Hughes, J. and Hennessy, S. 2001
Clearing the air: issues concerning the need for museum air quality standards in responding to external allegations at the National Gallery of Australia. Indoor Air Pollution conference, Copenhagen 8-9 November 2001

Padfield, T. 1994
The Role of Standards and Guidelines: Are They a Substitute for Understanding a Problem or a Protection against the Consequences of Ignorance?. In (Eds: Krumbein, Brimblecombe, Cosgrove & Staniforth) Durability and Change: The Science, Responsibility, and Cost of Sustaining Cultural Heritage, John Wiley & Sons Ltd, pp. 191-199.

Ryhl-Svendsen, M., (ed.)
The Website of Indoor Air Quality in Museums and Archives (http://IAQ.dk)

Tétreault, J. 1999
Standards for Levels of Pollutants in Museums: Part II. Indoor Air Pollution conference, ICN Amsterdam, (http://iaq.dk/iap/iap1999/1999_05.htm)

Thomson, G. 1986
The Museum Environment (2nd Edition) Butterworths, London

Back to Part 1: Abstract

Janet Hughes
National Gallery of Australia
GPO Box 1150
Canberra ACT 2600
E-mail: janet.hughes@nga.gov.au

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