Abstract This paper discusses the impact of certification on occupational health and safety management (OHSM) systems. Most research in the field has focused on how well such systems comply with voluntary standards such as OHSAS 18001 or with national and international legislation. However, this paper shows that even in cases of compliance, the certified systems have problems dealing with a range of contemporary complex work environment issues. Furthermore, certification also transforms the kinds of topics addressed and the procedures and activities applied in the system. Using the (in many ways successful) development of certified OHSM system in a manufacturing company in Denmark as a critical case, we demonstrate how certified OHSM systems unintentionally yet actively create an environment of ‘measurable and auditable facts’ shaped not only in response to legal and market demands for a safe work environment, but also as a consequence of the external demands for a visible and accountable work environment standard. We show how certified OHSM systems function like a hinge between internal operations and an external audience in a globalized market, thus giving priority to work environment issues that may later become demonstrable guarantees for a safe and healthy work environment. Thus the certified management system does not necessarily tackle the most urgent work environment issues and may exclude important aspects of the work environment such as psychosocial factors.