(In)visible and (in)vincible? Designing theory-based, evidence-based, and strategic communication materials to increase radon detection intentions

Radon, a naturally occurring radioactive gas, is the second leading cause of lung cancer worldwide. Despite the severe health risks, radon testing and mitigation remain insufficient. This issue is situated on multiple levels, ranging from the individual to the political, economic, social, and physical environment. While effective communication is essential to bridge this gap, radon health communication remains underexplored. This dissertation examines how strategic, theory- and evidence-based communication can enhance public engagement with radon-related behaviours. In the first phase of this research, the current communication was analysed. A systematic review of radon-related mass media interventions reveals that most campaigns rely on informational messaging, often failing to evoke personal relevance or emotional engagement. Moreover, in focus group workshops homeowners emphasised the need for communication strategies that extend beyond awareness-raising, addressing practical concerns such as financial support and regulatory measures. Participants also suggest tailoring messages to different behavioural stages, using approaches such as humour, personal letters, and testimonials. In the second phase, communication materials were developed and tested. An online experiment compared the impact of narrative-based and statistical messages on risk perception and behavioural intentions. Findings indicate that narratives are more effective in increasing personal and general risk perception while also strengthening intentions to seek information, test for radon, and consider mitigation. These results inform the development of a large-scale social media campaign, Radon Buster, designed to motivate individuals to take action. The campaign, implemented across Austria, Belgium, Ireland, and Slovenia, uses Facebook ads incorporating narratives, humour, and social norm nudges to attract attention and drive engagement. A controlled online survey experiment finds that exposure to these ads positively influences information-seeking intentions. A subsequent live Facebook study demonstrates strong audience engagement, with click-through rates and interaction metrics suggesting that social media can serve as an effective platform for radon risk communication. Overall, the findings highlight that radon communication must go beyond merely providing information, but should engage audiences, and align the messages with the decision-making process. While no one-size-fits-all solution exists, integrating social, emotional, and cognitive factors can enhance the effectiveness of communication strategies. This dissertation underscores the importance of a multi-level approach, combining stakeholder-targeted messaging with broader environmental interventions to ensure radon risk communication translates into meaningful action.