This study examines in urban area the housing conditions in asthma patients who called a first-aid association of doctors (SOS Medecins) and their relationships to symptoms. The patient population is compared with the non asthmatic population who called SOS Medecins during the same period. During the first six months of 1989, among 102,791 calls, 701 were related to acute asthma symptoms, and 100 non asthma patients were sorted at random as a control group. A telephonic questionnary has been carried out to asthmatic patients and to control group. A particular aspect of asthma in Paris is given in this study: the homogeneous distribution of asthma attacks in the different districts of Paris, (with a light prevalence in three districts of the city). Sex, age, occupation were non discriminant and no significant difference was established in housing conditions and indoor air pollution sources, between the two groups of asthma and non-asthma patients.