Indoor air quality in passive-type museum showcases

Air pollution in museum showcases is one main problem within preventive conservation. Applied materials for construction and decoration of showcases are potential emission sources for a broad variety of volatile organics. These might accumulate under those almost static conditions that are set within showcases due to conservation requirements. In particular, the knowledge of the potential hazardous impact of airborne pollutants on cultural assets caused a fundamental shift in material selection for showcase production during the last decades. However, systematic indoor air analyses within those modern-type showcases are missing so far. Hence, there is no knowledge if there has been achieved any improvement of air quality compared to traditional enclosures. In order to make the first move for evaluating the current situation in museum showcases, air analyses within passive-type enclosures of different construction types and ages have been performed. The focus was on concentrations of volatile and semi-volatile organic compounds (VOCs/SVOCs). Formaldehyde and organic acids have also been considered due to their known corrosive impact. All these target compounds have been determined by active and passive sampling and subsequent chemical analysis. It was found that in contrast to old-type showcases main emission sources have shifted from wood-based products and acid curing silicone rubbers to solvent-borne lacquers and neutral curing sealants. Due to secondary reactions, levels of acetic acid are still elevated. Thus, damage on artefact materials can still be suspected. The results reveal that a careful selection of construction materials is often not sufficient to lower air pollution levels. The development of risk assessment strategies and new technologies is therefore recommended. (C) 2010 Elsevier Masson SAS. All rights reserved.