On July 3, 2005, the Ddass of the Marne contacted the Cire Est to report three cases of respiratory disorders and/or blood disorders (one of the three cases exhibiting both conditions) among residents of the municipalities of Sainte-Ménéhould (51) and Les Islettes (55). The general practitioner who issued the report attributed these conditions to the operations of an aluminum smelter. The Ddass 51 therefore requested assistance from the Cire in November 2005 to verify the existence of a possible “spatio-temporal cluster related to the impact of emissions” from a nearby plant, according to the terms of the official referral. This document describes the steps taken to validate the doctor’s report based on the case descriptions. Contacts were thus made with the reporting doctor and, since two of the three cases involved factory employees, with the occupational health department and the Environmental Health Service of Ddass 51. (Report)