In early October 2010, health authorities were called upon to "address health issues" affecting teachers at a school in Brittany: fatigue, migraines, and upper respiratory tract irritations leading to sick leave. These symptoms had been occurring intermittently since September 2009, before spreading to the majority of the staff, resulting in the evacuation of the premises. All stakeholders were brought together in an interdisciplinary coordination team to share available information, coordinate necessary investigations—including medical examinations, individual interviews with a psychosocial counselor, a descriptive epidemiological survey, and an environmental assessment—and propose appropriate management measures. Air analyses revealed that the premises were poorly ventilated, leading to high CO2 levels in the classrooms. Concentrations of the other pollutants tested were within normal ranges. The psychosocial investigation revealed that the combination of several serious incidents at the school had generated significant anxiety, compounded by communication difficulties between management and staff and the staff’s perception that their complaints were being ignored. This situation had convinced the staff that being in the building posed a risk to their health. The epidemiological investigation concluded that there was no danger, with most of the symptoms attributable to confinement. The crisis was resolved through technical work on the building and improved communication. (R.A.)