T he load of disability and illness imposed on the Western industrialized nations by chronic bronchitis and emphysema is well known. I have chosen to talk on the topic of the prevention of emphysema because I think it is the central problem in relation to these diseases, and because serious and disabling chronic lung disease seems to involve centrilobular and panlobular emphysema far Thore frequently than just the changes commonly described as those of chronic bronchitis. However, in morbidity statistics it is perhaps better to link the two diseases together since the criteria of their distinction during life involve “degrees of probability” rather than of certainty. The most recent data of this kind I have seen are summarized in Table 1, which shows that emphysema and chronic bronchitis together ranked sixth in the United States as a cause of limitation of major activity, and affected 231,000 people. I have not seen exactly comparable data for Canada or Europe, but we have no reason to think that these countries would differ markedly except that in a number of Euorpean countries, particularly Great Britain, relatively fewer persons would be affected by heart conditions, with relatively more affected by emphysema and bronchitis. A few years ago, many chest physicians, including myseff, took the view that since most of the incidence of chronic bronchitis could be laid to the door of cigarette smoking, what we had to do was to stress, by every means at our disposal and on every occasion, that the prevention of emphysema consisted in carrying on a campaign against cigarette smoking. I am going to suggest that this concentration of emphasis, correct in itself, led us to ignore other possibilities in terms of prevention, and that we should now begin to use these in addition to our continued pressure on governments and politicians #{176}The Louis Mark Memorial Lecture, American College of Chest Physicians, presented at the 39th Annual Meeting; Toronto, October 21-25, 1973. * #{176}Dean, Faculty of Medicine, University of British Columbia, Vancouver. Reprint requests: Dr. Bates, Dean, Faculty of Medicine, University of British Columbia, Vancouver 8, B.C., Canada to take seriously the health problems caused by the cigarette. The principal reason for a shift in policy is that it appears that a simple reiterated emphasis on the dangers of cigarettes is not succeeding anywhere on a large enough scale to influence the incidence of the diseases we are discussing. This relative lack of success may be attributable to the unwillingness of governments to devote sufficient potential to this task: in Canada at least the effort has so far been only a token one, but even in Britain where a much more sustained effort has been made over a longer time period, the success has been meager. We should, therefore, turn our efforts now to the protection of the vulnerable individuaL In order to see how to accomplish this, we have to deal with three specific questions.