Many workers operate in environments that are inherently hazardous and that are subject to strict health and safety rules and regulations. We envisage a world in which physical work artefacts such as tools, are augmented with intelligent mobile nodes that are able to observe the working activities taking place, evaluate compliance with health and safety regulations and assist or actively enforce compliance with these regulations. This vision creates a new field of work in the area of health and safety aware intelligent mobile sensor networks. In this paper we describe a number of new challenges faced when developing mobile systems for compliance with health and safety regulations.