Since January 2025, the ‘low-oxygen’ treatment for combating insects in cultural heritage has been permitted again. The Netherlands is one of the first countries in Europe where ‘in-situ generated nitrogen’ has been approved as a biocide for cultural heritage. This is good news for museums and other collection managers who want to use this environmentally friendly pest control method to protect their collections from unwanted creatures.
This success was achieved thanks to close cooperation between European heritage organizations. On behalf of the Netherlands, the Cultural Heritage Agency (RCE), the Ministry of Infrastructure and Water Management (Environmental Protection and Transport Inspection), and the Board for the Registration of Plant Protection Products and Biocides (Ctgb) joined forces to make this happen.
Safe and Yet Forbidden?
In-situ generated nitrogen is ordinary air from which oxygen has been filtered. It is lethal to organisms that need oxygen to survive while being harmless to the environment and the materials being treated. Therefore, this safe and clean pest control method has been used since the end of the last century against pests in cultural heritage. However, in 2012, this method was classified as a biocide at the European level and came under the Biocide Regulation. This means it could only be used with a permit, and nobody applied for this harmless substance. It suddenly became a forbidden substance.
Tolerated
There was certainly interest from the industry to get the method approved, but no one wanted to take on the work and high costs. It was not commercially interesting enough, but for the heritage world, there was a great necessity to continue using the substance. In the Netherlands, several museums have a ‘low-oxygen chamber’ to treat incoming and affected objects.
Thanks to a legislative article in the Biocide Regulation, a derogation was requested so that the substance was tolerated for a number of years, provided an application for approval was made.
European Cooperation
To that end, European heritage organizations joined forces. After preparatory work from Austria in 2019, German colleagues from the Stiftung Preussischer Kulturbesitz in Berlin took over and submitted the dossier to the European Chemicals Agency (ECHA) to demonstrate the efficacy of nitrogen as a pesticide against insects in heritage. With scientific input from the Netherlands and Denmark, it succeeded in getting ‘in-situ generated nitrogen’ classified as an active substance on the so-called Annex I list of low-risk biocides. This opened the way for the Germans to obtain a permit for use in closed spaces such as treatment rooms and tents. They can now notify other European countries so that the method can also be applied there. The Netherlands is one of the first countries.
Cultural Heritage at the Forefront Against Poison
This is truly remarkable
, says Agnes Brokerhof, a researcher at the National Heritage Laboratory of the RCE. Cultural heritage has taken the lead in obtaining a clean and safe pest control method that other ‘industries’ can also use. Moreover, the approval is available to anyone who wants to use it, without commercial interests being a limitation.
The current approval only applies to use on cultural heritage. But because the substance is on the Annex I list, any company can apply for approval for its own application at relatively low costs. The Board for the Registration of Plant Protection Products and Biocides (Ctgb) has never seen anything like this before with biocides (though with plant protection products it has). Cultural heritage has paved the way for humane and environmentally friendly pest control of insects.
Brokerhof: In a time of pollution, poison, and misery, it is fantastic that this clean pest control method is back. The Collection Center Netherlands (CCNL) also has two treatment rooms that operate on nitrogen, so it was in our own interest. But it was also a principled matter. We introduced the method 25 years ago as a safe and clean alternative to all toxic gases in the museum world, and it was embraced then. The news that nitrogen was classified as a biocide and was not on the EU biocide list, and thus still a forbidden substance, hit like a bomb in 2019. The reason it was on the forbidden substances list has to do with politics. But we have gone full steam ahead to first get our substance on the biocide list and then obtain a permit. Now, 5 years later, we are there. We are proud of this result that we have achieved together with the Ministry of Infrastructure and Water Management (Environmental Protection and Transport Inspection) and the Board for the Registration of Plant Protection Products and Biocides (Ctgb), and thanks to the generous efforts of our German colleagues.