Introduction: Exposure to respirable dusts is a construction industry health issue due to the number of workers concerned by this exposure. However, few studies are interested in the activity of workers exposed to these dusts. Methods: An ergotoxicology methodology is relevant in order to assess and prevent dust exposure. This methodology is divided into 5 steps: (i) social construction of the study with several actors; (ii) global analysis in order to explore work site, and to choose situations on which to focus, based on assumptions; (iii) observations with camera and dust concentrations measuring instruments; (iv) self-confrontation interview with workers who were the subject of observations and measurements, and (v) a feedback session with actors of study allowing discussions on possible prevention solutions. Results: This methodology proposes an original understanding of dust exposure by highlighting its multicausality. It shows a plurality exposures situation and their macro-determinants, representations of dust risk by workers, compromises between protection and production activities in connection with organizational issues. Discussion: Coupling measurement with video is a resource to understand exposure situations and their determinants, developing collective actions and discourse on activity. This allows us to support there is insufficient consideration of real conditions for carrying out tasks exposing to dust and the need to take activity into account through an ergotoxicological approach to exposure. Conclusion: This ergotoxicological method could be reproduced and perfected in other situations to serve as a lever for evaluation and prevention of dust exposure.