From the 1660s onwards, France tried to establish itself as a leading maritime and colonial power. The first French East India Company allowed a decisive penetration into the Indian Ocean, while the foundation of the Rochefort arsenal was the starting point of a great shipbuilding effort.

The archives of the State Secretariat of the French Navy, ports, and learned societies, as well as printed scholarly literature, testify to an increasing mobilisation around the health of the “gens de mer.” Most of the actors involved in this reflection, whether doctors or surgeons, naval officers or engineers, scholars or inventors, agreed in associating seamen's diseases with the poor air quality prevailing within ships. The environment of seafarers was thus definitely regarded as harmful. However, the atmosphere of a ship was also seen through the possibility to reshape it and reduce its dangerousness, with adapted behaviours, careful maintenance, or technical solutions. This was crucial to ensure the circulation of human beings and goods across the French overseas empire, but also to defend it from the threats associated with the major conflicts of the second half of the 18th century.

This article highlights how environments regarded as “pathogenic” were conceived and reshaped during the second half of the early modern period in France, using the example of naval hygiene. It examines the strategies designed and implemented to combat the “noxious” air of French ships, in particular through the regulations introduced since the end of the 17th century, and considers how this issue has stimulated the search for technological solutions.