Preservation efforts of Japanese museums threatened as manufacturer stops selling effective fumigation gas

Museums and other facilities may have trouble removing insects and mold from cultural assets in the future because a company that produces gas for fumigation has decided to stop selling the product most commonly used in museums across the country.

There are other gases available, but they can only be used in certain parts of the country or are not as effective. The situation has led to increasing concern among the parties involved.

Nippon Ekitan Corp. is a Tokyo-based company that has been selling gas for disinfecting cultural property longer than any other company in Japan. It has been selling the Ekihyumu S-gas in question since the 1970s.

The company recently decided to stop selling Ekihyumu S in March 2025. This gas is effective against both insects and fungi and is widely used in museums.

Nippon Ekitan’s decision was partly prompted by a drastic increase in the price of the materials needed to produce the gas. It also contains ethylene oxide, which can be harmful to the natural environment, and the Ministry of the Environment is calling for a reduction in ethylene oxide emissions.

“We cannot continue production, also for the safety of the people working on the work. Developing an alternative product is also difficult. We are very sorry, but we want the people involved to understand the situation,” a company official said.

Fumigation is used to kill harmful insects and fungi that cling to the inside of Buddhist statues, ancient documents and other cultural properties. The procedure is performed by filling a closed space with gas.

Such work is usually done on a regular basis, but there are now moves to reduce the frequency due to limited budgets or safety concerns.

However, there are still many cases where fumigation is necessary, for example when harmful insects appear in large numbers and when cultural properties are brought from elsewhere to museums.

Bunkazai Chukingai Kenkyujo, a public interest foundation that aims to prevent damage to cultural properties by insects and fungi, certifies three types of gas currently available as having a low negative impact on cultural properties.

One of them is Ekihyumu S. The company that processes one of the other gases only serves the Kanto region and nearby areas, while the other gas is effective against insects, but not against fungi. Moreover, the latter gas is only handled by a few service providers.

Museum officials and other stakeholders are becoming increasingly concerned.

At the Kyoto National Museum in Kyoto, the fumigation chamber is exclusively for Ekihyumu S-gas. The chamber would have to be modified to accommodate other types of gases. In addition, the alternative gas machine, which is effective against both insects and mold, generates air currents, which can lead to problems such as gold leaf peeling off sculptures.

There are many fragile cultural assets from which mold cannot be easily removed, so it is important that fumigation gas can kill mold.

“We cannot find an alternative measure,” said Junko Furihata, chairman of the museum’s Conservation Science Department.

Yukio Komine, a research officer from the conservation and repair instruction bureau of Nara National Museum in Nara, said: “From the point of view of cost, it is not realistic to involve service providers from the Kanto region.”

Fumigation is effective in small spaces where human hands cannot reach.

Yoshinori Sato, head of the Department of Biological Sciences at the Tokyo National Research Institute for Cultural Properties, said: “If we cannot decontaminate, many problems may occur at once in several years.”