A prevention strategy against fungal attack for the conservation of cultural assets using a fungal index

• A prevention strategy against fungal attack was developed for the conservation of cultural assets.
• The strategy consists of fungal-index assessment at each point in a given room.
• The fungal index assesses conditions critical for fungal growth.
• Systematic selection and evaluation of countermeasures are included in the strategy.
• The strategy is applicable to IPM (Integrated Pest Management) in museums.

The present study aimed to establish a prevention strategy to protect cultural assets from fungal attack. A fungal index that assesses conditions critical for fungal growth was determined using a fungal detector in the storerooms of historical buildings in Higashiomi area, Japan. The index measurements were repeated after 4 weeks' exposure of the detectors during the seasons when relative humidity outdoors and/or indoors was high. The index values obtained were from below the measurable lower limit to above the upper limit. The prevention strategy proposed was as follows. Each microclimate was categorized into three levels, A, B, or C, depending on the index values, <1.8, 1.8–18 or >18, respectively. If all microclimates in a room maintain level A continuously, the room is considered free of contamination. If some microclimates maintain level B, fungal contamination might occur. If microclimates maintain level C, fungal contamination is unavoidable, and countermeasures should be taken promptly. Finally, fungal indices are measured for evaluation of the countermeasures and for level-A confirmation. The systematic use of fungal indices will provide practically useful information for conservation and must be applicable to IPM (Integrated Pest Management) in museums and libraries.