The industrial disaster that occurred on September 21, 2001, in Toulouse resulted in the total or partial destruction of 1,300 facilities, affecting nearly 21,000 jobs. About five months after the explosion, 1,800 workers were still on furlough. A massive mobilization of emergency and safety resources was carried out: 1,430 firefighters and civil defense rescue workers responded during the first six days, not counting security personnel and the efforts of hospitals in the Toulouse metropolitan area. An epidemiological surveillance program was established to assess the effects of the explosion on the health of workers and rescue personnel. A cross-sectional survey was conducted one year after the explosion. Its objective was to assess the material, physical, and psychological consequences, as well as the need for medical care. In addition, data necessary for a subsequent analysis of the causes of death among the surveyed population were collected. A cohort of volunteers designed to assess the health impact and the medium-term (five-year) socio-professional outcomes of the individuals was initiated in May 2003, in cooperation with the Health Examination Center (CES) of the Toulouse Primary Health Insurance Fund (CPAM) and the Technical Support Center for Health Examination Centers (Cetaf). Only preliminary results are presented in this article; they concern rescue workers and workers in the area near the explosion. (R.A.)