The explosion at the AZF factory on September 21, 2001, was a major industrial accident with two notable characteristics: the impact on the entire city, far beyond the industrial site, and its human and material consequences—not only immediate but also long-term—on the personal, family, and professional lives of a large number of Toulouse residents in the months following the explosion. To account for these specificities, it was decided to conduct a study to, on the one hand, measure the impact on the general population, and on the other hand, assess the health consequences in the medium term, in order to estimate the direct and indirect impact of the disaster. (R.A.)