Report on the Forum, “Considering the Conservation of the Museum Collections After the Suspension of the Major Fumigation Gas Sales”

The general discussion

Research introduction by organizations related to Museum IPM

　On February 21, 2025, the Center for Conservation Science (CCS) hosted a forum titled “Considering the Conservation of the Museum Collections After the Suspension of Major Fumigation Gas Sales.” This event was co-hosted by the Agency for Cultural Affairs, the Japan Society for the Conservation of Cultural Properties, and the Japan Society for Scientific Studies on Cultural Properties.

　In cases of extensive insect and mold damage, gas fumigation is used to mitigate the damage. Alternatively, gas fumigation may be utilized to prevent insects and molds from infesting incoming collections. This method has also been applied to museum collections that have suffered fungal damage due to disasters. Gas fumigation is a crucial technology for preventing biological deterioration in the conservation of museum collections in Japan. However, the sale of one of the primary fumigation gases was scheduled to cease at the end of March 2025. This decision stems from the growing awareness of the negative impact of fumigation gases on human health and the global environment.

　At the forum, experts and organizations in this field were invited to discuss alternative methods for conserving museum collections without the use of gas fumigation, in response to the contemporary societal demand for sustainable practices.

　In the keynote speeches, Mr. YONEMURA Sachio (Agency for Cultural Affairs) and Ms. KIGAWA Rika (Kyushu National Museum) spoke about the future of conservation in museum collections, focusing on Integrated Pest Management in museums (Museum IPM). Additionally, during the lunch break, Mr. WATANABE Hiroki (Kyushu National Museum) and Mr. SHIMADA Megumi (Tokyo National Research Institute for Cultural Properties) reported on international research topics related to Museum IPM. This was followed by lectures from Mr. HIDAKA Shingo (National Museum of Ethnology), Mr. IWATA Yasuyuki (Japan Institute of Insect and Fungal Damage to Cultural Properties), and Mr. MABUCHI Hajime (The National Center for the Promotion of Cultural Properties) on the practical applications of Museum IPM, the qualifications associated with it, and the theory and practice of mold control.

　The general discussion was moderated by Mr. TATEISHI Toru (The Museum of the Imperial Collections, Sannomaru Shozokan. Each speaker, including Mr. KODANI Ryusuke (Cultural Heritage Disaster Risk Management Center), Mr. WADA Hiroshi (Tokyo National Museum), Ms. FURIHATA Junko (Kyoto National Museum), Mr. WAKIYA Soichiro (Nara National Research Institute for Cultural Properties), and Mr. TAKAHATA Makoto (Imperial Household Agency) took to the stage to discuss methods for conserving museum collections without relying on gas fumigation.

　The venues were the seminar room and conference room (satellite venue) on the basement floor, and in the foyer, organizations related to Museum IPM showcased booths highlighting their recent research. Approximately 170 individuals attended in person, while around 750 accounts were registered for a simultaneous online broadcast, resulting in a substantial audience. The CCS hopes that this forum provided an opportunity to foster more dynamic discussions and enable those concerned to take meaningful steps toward addressing these issues.

On-Site Inspection of the Humidity-Controlled Warm-Air Treatment Facilities for the Bell Tower of Okariden Hall

Conducting an on-site inspection.

The bell tower of Okariden Hall.

　On May 15, 2024, we visited Nikko Toshogu Shrine to inspect the “humidity-controlled warm-air treatment” facilities for the bell tower of Okariden Hall. Traditional gas fumigation for insect extermination has become difficult to continue due to safety and environmental concerns. This new treatment is a method to exterminate insects that damage the wood of structures, such as pillars and beams, by heating the wood to high temperatures (around 60℃). By controlling the humidity during the treatment to maintain a constant moisture content in the wood, it is possible to raise the temperature inside the wood without significantly affecting its physical properties. The new method is therefore expected to be a means to replace gas fumigation.
　To date, the research team, consisting of the Association for the Preservation of the Nikko World Heritage Site Shrines and Temples, Kyoto University, Total System Laboratory, Kansai Electric Power Co., Inc., KANSO Technos Co., Ltd., and the Tokyo National Research Institute for Cultural Properties (TOBUNKEN), has conducted three verification treatments on actual buildings. In addition to evaluating the insecticidal effects and impact on the structures, considerations were also given to environmental impacts such as noise and energy consumption. As a result, the humidity-controlled warm-air treatment was established as a practicable new method for insect extermination in wooden structures.
　Last year, for the first time on a designated cultural property, the treatment was carried out at the Gohotendo Hall of Rinnoji Temple. This time, it was conducted at the bell tower of Okariden Hall, marking the second case for a designated cultural property. Going forward, we aim to promote this method as the new standard for insect extermination in wooden structures.