Giovanni Sturaro

Environmental monitoring in four European museums

In a European multidisciplinary research project concerning environmental diagnostics, museums have been selected, having different climate and pollution conditions, i.e.: Correr Museum, Venice (Italy); Kunsthistorisches Museum, Vienna (Austria); Royal Museum of Fine Arts, Antwerp (Belgium); Sainsbury Centre for Visual Arts, Norwich (UK). Some field tests investigated the microclimate, the gaseous and particulate air pollution and the biological contamination to suggest mitigative techniques that may reduce the potential for damage in the long run. Potential risk factors are generated by imbalance in temperature and humidity, generated by heating, air conditioning or ventilating system (HVAC), or the building structures, exchange of outside air, or large visitor numbers. HVAC may also enhance indoor gaseous pollution. Plants and carpets represent potential niches for bacterial colonisation. Pollutants and particles have been recognised having partly external and partly internal origin. Tourism has a direct negative impact, i.e. transport of external particles, release of heat, vapour and CO2, as well as generation of turbulence, which increases the deposition rate of particulate matter. However, the main problem is that the microclimate has been planned for the well being of visitors during only the visiting time, disregarding the needs of conservation that requires a constant climate by day and by night. In some of these cases, better environmental niches have been obtained with the help of showcases. In other cases, showcases worsened the situation, especially when incandescent lamps were put inside

Indoor air quality at the Correr Museum, Venice, Italy

Two multidisciplinary field surveys, one in winter and the other in summer have monitored the indoor microclimate, air pollution, deposition and origin of the suspended particulate matter and microorganisms of the Correr Museum, Venice. In addition, this study was focused to identify the problems caused by the heating and air conditioning system (HAC) and the effects due to the presence of carpets. Heating and air conditioning systems (HACs), when chiefly designed for human welfare, are not suitable for conservation and can cause dangerous temperature and humidity fluctuations. Improvements at the Correr Museum have been achieved with the assistance of environmental monitoring. The carpet has a negative influence as it retains particles and bacteria which are resuspended each time people walk on it. The indoor/outdoor pollutants ratio is greater in the summertime, when doors and windows are more frequently open to allow for better ventilation, illustrating that this ratio is mainly governed by the free exchange of the air masses. The chemical composition, size and origin of the suspended particulate matter have been identified, as well as the bacteria potentially dangerous to the paintings. Some general suggestions for improving indoor air quality are reported in the conclusions.

The microclimate inside the Pollaiolo and Botticelli rooms in the Uffizi Gallery, Florence

To characterise the evolution of the internal climate in some of the rooms of the Uffizi Gallery (Florence), the main thermo-hygrometric parameters (air temperature, relative humidity, specific humidity, dew point, atmospheric stability) were measured automatically for some years, and also manually, with seasonal measuring surveys. Measurements were started in 1997 and are still continuing. The use of heating, air conditioning, ventilation and lighting and the daily flux of a huge number of visitors produce rapid changes and marked thermo-hygrometric gradients in the rooms. Sharp variations are found when the system is switched on in the morning, and switched off in the evening, instead of operating day and night, which is desirable for the preservation of the paintings. The humidifying system in the Pollaiolo room was found to be much too powerful, so that, instead of mitigating the relative humidity drop that is expected after a daily rise in air temperature, it increases it, forming an undesired excess of moisture. In the long run, all these cycles risk becoming harmful to the exhibits if air-temperature and air-humidity control is not regulated in accordance with the results of this study. These problems and the possible approaches to the installation of a new plant and the mitigation of these negative effects are discussed.

Use of proxy-documentary and instrumental data to assess the risk factors leading to sea flooding in Venice

Abstract Due to its geographical position, and because it was built at sea level, Venice is extremely sensitive to climate changes and, in the future, risks being submerged as a consequence of the expansion of oceanic water in response to global warming. A key problem is the increasing frequency of storm surges with the sea flooding the city (locally named acqua alta ) that has reached an unsustainable level. After careful examination of both proxy documentary and instrumental data, it has been possible to reconstruct the extreme weather conditions and natural hazards, which have taken place in the last two millennia, with particular reference to surges. A key problem with proxy data from written sources is that periods with missing data may be misinterpreted as ‘normal’, or that inaccurate reporting may lead to duplication or even multiplication of events. For this reason, the accuracy of the proxy data has been checked by comparing it with other known events. An accurate series of the flood surges has been obtained combining instrumental observations (1872–2000) with documentary data for the previous period. The period of minimum solar activity of Sporer (1416–1534) was anomalous for surges. Not only have meteorologically perturbed periods been identified, but also the effects of the accelerated subsidence of the city and of certain works undertaken in the lagoon that varied the exchanges between the sea and the lagoon. The impact of subsidence and of the modified dynamical exchanges of the lagoon on the change in flooding frequency has been established. During the instrumental period, the tide gauge measured a 31-cm rise. The frequency of surges has dramatically increased since the 1960s, reaching about two flooding events per year, the greatest value since 792 AD.

Showcases: a really effective mean for protecting artworks?

Abstract Field and laboratory tests have been performed to analyse the response of showcases to environmental factors. The following properties have been tested. Thermal damping. Greenhouse effect and IR absorption of the materials most commonly used for panes. Impact of different types of light sources. Humidity buffering capacity and rate. Inside/outside exchanges and leakage. Penetration and deposition of airborne particles. Advantages and disadvantages of airtight and non-airtight showcases in view of protection against dust, corrosive self-outgassing of VOC and microbiological infection and growth. A proposal is made to indicate all of the case characteristics, and their response to the ambient, with appropriate indexes, which represent the level of quality in view of the specific problems of the user. A quantitative evaluation of each index quality level is also discussed.

Thermodynamic exchanges between the external boundary layer and the indoor microclimate at the Basilica of Santa Maria Maggiore, Rome, Italy: the problem of conservation of ancient works of art

The Basilica of Santa Maria Maggiore, Rome, is an example of how ancient buildings with thick walls lessen the impact of the external temperature and humidity variations. The external influence on the internal microclimate is studied in order to gather information on how the building exchanges heat and moisture. Correlations between outdoor and indoor values are found. The results are applied to the calculation of the condensation-evaporation cycles inside micropores due to the Kelvin effect, to assess their impact on works of arts placed inside and outside the Basilica. It was found that the building attenuation is not sufficient to avoid damage due to condensation-evaporation cycles on stones and plasters. Some suggestions are made in order to mitigate the temperature variations during the liturgical offices.

Multidisciplinary Environmental Monitoring at the Kunsthistorisches Museum, Vienna

Abstract Two multidisciplinary field surveys, one in winter and the other in summer, have monitored the indoor microclimate, the air pollution, the deposition and origin of the suspended particulate matter and the microorganisms of the Kunsthistorisches Museum, Vienna. These surveys were part of a European project aimed at identifying potential environmental risks for conservation in museums. Experimental methodologies were refined within this study. The project underscores pros and cons of the heating ventilating and air conditioning system, proposing a more effective filtration, since the system seemed to worsen indoor pollution. The impact of mass tourism during a special exhibition was investigated, showing that even a good ventilation is unable to deal with the heat and moisture released by huge crowds. The sources of gaseous and particulate pollution were discussed. Microbiological investigations identified a considerable load of bacteria. The cleaning of paintings by brush is shown to resuspend a considerable amount of particles, which are free to deposit again on the paintings.