Allergic conditions, and bronchial asthma in particular, appear to be more common in industrialized countries, and the role of air pollution has been suggested. A survey was conducted in collaboration with the School Health Service in the Saint-Nazaire area, targeting elementary schools. The main objective was to measure the prevalence rate according to the children’s age. In addition, two geographic areas were identified: one near numerous industrial sites east of Saint-Nazaire (Area 1), and the other, a rural area, in the northern part of the region (Area 2). The secondary objective was to determine a relationship between prevalence rates and residential area.