[Preventive health actions. Various levels of time, of the role of health professions and of individual participation].

At a time when increasing emphasis is placed on promotive and preventive measures in health care, it is important to bear in mind that the ways and means of prevention are diverse and multidisciplinary. The author briefly discusses the levels which are to be considered, in regard to the timing of the intervention (primary, secondary and tertiary prevention), the requisite professional contribution, and the importance of the individual's active participation. Participation is highly desirable, and is in fact indispensable for improvement of the "civilization" health problems we are now facing. It is not always easy, however, to determine its optimal pattern and intensity. It is also necessary to take into account the inteface situations between preventive measures and freedom, at the individual as well as the social level.