Asterixe: Past, Present and Future – Expert Meeting Report 2024

Executive Summary The ‘Asterixe: Past, present and future’ expert meeting in May 2023 involved a series of activities to plug gaps in the history of the project, review ongoing research initiatives, and inform future strategic directions for research on the Asterixe. This report captures the retrospective nature of the meeting, aiming to preserve the institutional memory of this pioneering project, document lessons learned, and outline its relevance as a case study for long-term exposure trials. The event highlighted the innovative aspects of the Asterixe project, such as its complex sample design, and explored how these approaches could inform future research methodologies. The expert meeting evolved around a series of structured yet flexible activities, including individual interviews and collaborative discussions. It brought together some of the people involved in the original project with those working on the Asterixe now. The agenda included introductions, questions about the initial motivation and design of the project, and presentations on recent research activities by teams from the Fraunhofer Institute for Building Physics (IBP), Getty Conservation Institute, and the University of Oxford. Participants also went on a guided tour of the Asterixe test site and the IBP institute to discuss the remaining Asterixe specimens and the methods deployed to investigate them. The day concluded with a recollection and debriefing session, fostering reflections on the event and the project's broader legacy. The key anticipated and planned outputs included the collection of additional historical data and photographs, recording and transcription of senior Asterixe experts’ memories, and the production of this report. Crucially, the meeting also served as a starting point for the formation of a network of interested parties for an international research community focusing on long-term, large-scale exposure trials. By using the Asterixe project as a model, this network aims to draw from past successes and challenges to guide the design and governance of future trials. Overall, the Expert Meeting served as a vital step in both preserving the Asterixe project’s institutional knowledge and memory and providing insights for long-term, large-scale exposure trials. The Asterixe project offers a unique case study that underscores the need to balance innovative designs with practical implementation, making it a valuable reference point for future initiatives. Key take home messages are: • Persistent interest in stone exposure trials • Need for a good balance between ‘too simplified’ and ‘too complex’ designs • Strong collaborative interest in researching the effects of air pollution and microbiology on stone bioprotection • Need to establish a global network for studying the environmental impact on natural stones and their conservation