The rejection of siting controversial facilities in urban areas periodically resurrects the discussion regarding site-specific technologies that pose risks characterised by severe impacts and extremely low probabilities. This article discusses this topic from an ethics perspective, focusing on the problematic evaluation of minimum safe distances that should be established between potential accidents and exposed residents. Two different approaches to the assessment of such ‘spatial safety’ measures – namely, the probabilistic and deterministic approaches – are compared. The scope of this article is to unveil these approaches’ implicit ethical assumptions and – more generally – facilitate a considered choice between different approaches towards planning ‘risky’ land uses.