Little is known about the delegitimation experiences of people who associate their health problems with the indoor air quality of their homes (i.e., indoor air sufferers). From other contexts, it is known that people suffering from contested illnesses frequently report delegitimation from authorities and laypersons. Therefore, we analysed delegitimation experiences among indoor air sufferers, focusing on how they explain why others delegitimize them. Two types of qualitative data-semi-structured interviews with eight people and essays written by 28 people-were subjected to a thematic analysis. Thematic analysis revealed three themes: 1) lack of understanding; 2) others' lack of morality; and 3) social discrimination and inequality. This study demonstrates that indoor air sufferers are vulnerable as individuals and as a group, and suggests that authorities working with people suffering from indoor air problems in homes must pay more attention to sufferers' ability/willingness to trust people and the system responsible for their care.