The Basis for Debating Standardization of Risk for Land-use Planning is Incomplete

The practice of using quantitative risk assessments (QRAs) for managing risks in land-use planning varies between countries. Some regulatory regimes are highly prescriptive in terms of explicit requirements on methodology, assumptions, modelling tools, input data, risk criteria, etc. Others require risk analyses to support decision-making without regulating the details. The present study seeks to investigate different levels and forms of standardization and explores the knowledge base supporting the adoption of a specific regulatory regime. The experiences and practices from Sweden, Norway, Denmark and the Netherlands is assessed. The study reveals that no formal structured evaluation or assessment, qualitative or quantitative, of the effects of the chosen approach has been performed in any of the countries. Also in scientific literature, there seem to be a lack of empirical data from this kind of evaluations. However, the debate whether increased or a certain type of standardization is desirable isongoing. A main conclusion from the study is that with ambiguous perspectives on how risk can or should be standardized for land-use planning and with limited empirical data available, the basis for debating appropriate levelof standardization of risk is incomplete. More knowledge of the effects from different risk regulatory approaches is required to form a sound basis for future changes to risk regulations