Relationship of respiratory symptoms and pulmonary function to tar, nicotine, and carbon monoxide yield of cigarettes

The role of cigarettes in the causation of chronic obstructive lung disease (increased resistance to the flow of air in and out of the lungs) is well established. In an attempt to reduce the health risks of cigarette smoking, manufacturers have reduced the per-cigarette yield of tar, nicotine, and carbon monoxide (CO). Studies have shown that the risk of developing certain types of cancer is reduced by switching from a brand of cigarette high in these substances to one which has lower concentrations, but the effects of tar, nicotine, and CO levels on the development of chronic obstructive lung disease is less certain. To further study this issue, 690 subjects who were regular smokers were questioned about their smoking habits and respiratory symptoms (chronic cough, phlegm, and shortness of breath); 414 of these subjects were also given tests of respiratory function. After statistical corrections had been made for the intensity and duration of smoking and for the depth of inhalation, there was no relationship between the tar and nicotine yield of a smoker's cigarette and the risk of developing chronic phlegm, cough, or shortness of breath. But among the subjects who were tested for current respiratory function, there were statistically significant relationships between the daily dose of tar, nicotine, and CO (that is, the per-cigarette yield multiplied by the number of cigarettes smoked per day) and lung function. However, the association between tar, nicotine, and CO dose and pulmonary function was weak, and was much smaller than the adverse effects caused by smoking any type of cigarette compared with not smoking at all. (Consumer Summary produced by Reliance Medical Information, Inc.)