[Indoor air pollution and health: study of various problems]

Human beings are living between 70 and 90% inside of premises, where numerous air pollutants are existing: some of them have outdoor sources (industry, domestic burning, car traffic), some are produced indoors by human activities and equipment, by animals, or by various materials, products and furniture. According to their nature, they are listed as biological, physical or chemical pollutants. About health, serious poisonings and acute effects attributed to indoor air pollutants, and even short term effects (like sick building syndrome, infectious illness, pneumopathies,...), can be relatively easy to distinguish. Inversely the involvement of these pollutants in long term effects (like chronic bronchitis, asthma, cancers,...) is more difficult to establish. During the last 15 years we carried out several studies, which allowed us to separate the chemical air contaminants into two categories: those produced outdoors (sulphur dioxide, lead, chromium, nickel, nitrates), of whom we calculated the penetration coefficients, and those from both origin, outside and inside (nitrogen oxides, carbon monoxide, ammonia, aldehydes, particles, cadmium, vanadium, sulphates, ammonium salts). Aldehydes, which present important health risks, were especially investigated: in an office where several cigarettes were burning the measured concentrations were high in comparison with the threshold values existing in some foreign countries; in a cafeteria they were relatively low. To estimate the impregnation of non smokers by environmental tobacco smoke, we also determined, during same spaces of time, on the one hand nicotine in air, on the other hand nicotine and its metabolites excreted in the urine of exposed people. We thus observed that, in "real" situations, this impregnation is as a general rule extremely low.