In this interim presentation, we ask how the French fire department establishes a security (or safety) culture in the face of biological risk. We argue that French firefighters’ security culture must be understood as a technoscientific culture and that it revolves around technoscientific artefacts (documents, masks, detection kits, etc.). In doing so, we show that French firefighters’ claim to expertise hinges on two kinds of knowledge: theoretical and written knowledge (i.e. RCH1-4 courses, the Guide national de référence: Risques chimiques et biologiques) as well as embodied/tacit knowledge (mastering measurement equipment, knowing how to put on and take off protective clothing, knowing how to decontaminate certain surfaces). Biological risks challenge usual claims to expertise regarding chemical and radiation risks because their temporality, spatiality, and detectability pose new problems.