Mortality from lung cancer and coronary heart-disease in relation to changes in smoking habits.

Changes in the type and quantity of cigarettes smoked in the United Kingdom from 1956 to 1971 are compared with changes in the dealth-rates due to lung cancer and coronary heart-disease (C.H.D.) from 1956 to 1973. Associated with a change in filter cigarettes there has been a decrease in lung-cancer mortality among men aged less than sixty years despite little change in the number of cigarettes smoked. In contrast, lung-cancer mortality has increased in women along with their cigarette consumption. C.H.D. mortality has continued to increase in both sexes, but to a greater extent in women. These changes are consistent with the hypothesis that, in tobacco smoke, tar is the principal aetiological factor in lung cancer, whereas carbon monoxide or other gaseous constituents are involved in the development of C.H.D.