To define qualitative and quantitative categories of exposure to environmental tobacco smoke (ETS) and to assess possible differences for life-style factors between exposed and unexposed women, we studied 867 nonsmoking women (8-73 aged), selected from a general population sample living in the Po Delta area (near Venice, North Italy). Information was collected by a standardized questionnaire. ETS exposure at home, at work or elsewhere was considered. There was a prevalence of ETS exposure of 46% in the whole sample; the rate had a negative association with age. Exposure to ETS occurred more frequently at home, either singly (56%) or in combination with school/work and other places (75%). Exposed women were significantly younger, taller and lighter than those unexposed. Logistic regression on 20+ aged women showed that single-separated-widowed, workers, women living in a rental house, and women with a central forced air heating were significantly more exposed to ETS. Crowding index (n inhabitants/n rooms of the house) was significantly higher in those exposed. These results indicate that ETS exposure is quite frequent in Italian women and that some life-style factors (e.g. marital status or occupational status or some home characteristics), should be considered in the study of relationship between passive smoking and respiratory health.