Research framework: For a family, eco-citizenship means among other things adjusting their domestic practices to their desire to act in favor of the environment and the preservation of its resources. In the event of a child’s chronic respiratory illness, parents receive medical recommendations designed to protect his or her health. These recommendations relate to the layout and upkeep of the home, and concern some of these practices.

Objectives: This article aims to show how the family redefines its practices by articulating its values related to health and the environment.

Methodology: This research is based on a qualitative study carried out between 2018 and 2020, involving interviews and observations in the homes of 46 families living in Brittany, France, who have a child with cystic fibrosis or asthma. The purpose of the survey was to ethnographically describe domestic hygiene practices, which may stem from values attached to both health and the environment.

Results: This article analyzes the dynamics of change in the family’s ecological domestic practices through the prism of the child’s chronic respiratory illness and its implications. It points out the factors influencing the family’s eco-citizen trajectory in this particular context.

Conclusion: The inflection given to this trajectory depends first and foremost on the family’s ways of being and doing, and the cultural and social context that shapes them. It then relies on the specific characteristics of the disease, the context in which it is treated and the way in which the medical authority integrates environmental issues into its health guidelines.

Contribution: This article looks at children’s chronic respiratory illness as one of the key factors in the construction of a family’s eco-citizenship and its practical implementation. It questions the medical establishment as to how it takes into account environmental values in a perspective of family’s quality of life.