Our study was carried out in winegrowing in France and relates to the prevention of pesticide exposure situations. During treatments, the sprayer is a technical determinant directly responsible for these situations because of its design. The objective of our study is to gain a better understanding of pesticide exposure situations during the use of sprayers, by identifying the design of these machinery and the regulations that apply to it as a chain of determinants. Focusing on activity-centred ergonomics, this qualitative study formulates ergonomic (video recorded observations and interviews) and legal (content regulation) analyses at each level of this chain (treatments activities, sprayer design activities, regulation, and regulation development activities). The results highlight the role of design and regulation in the emergence of pesticide exposure situations, due to a little consideration of the real work of winegrowers. This means that design and regulation are relevant change levers for sustainable preventive action.