Respiratory morbidity in smokers of low- and high-yield cigarettes.

To study the association between smoking cigarettes with a low yield of tar and nicotine (tar less than 15.0 mg per cigarette and nicotine less than 1.0 mg) and respiratory disease, we reviewed the medical records of 4,610 current, regular cigarette smokers and 2,035 persons who had never used any form of tobacco and who were enrolled in a smoking study. In the year after recruitment to the study, the percentage of subjects with pneumonia or influenza was lower in female but not in male smokers of low-yield cigarettes. The percentage of subjects with any disease of the respiratory tract was lower in both male and female smokers of low-yield cigarettes. In multiple logistic regression analyses in which tar was included as a continuous variable and in which we also controlled for age, sex, race, and number of cigarettes smoked per day, smoking lower tar cigarettes was associated with lower risk for pneumonia or influenza, but not with the risk for other acute respiratory infections, other diseases of the upper respiratory tract, chronic obstructive pulmonary disease and allied conditions, or all respiratory diseases considered as a group. In other multiple logistic regression analyses, in which we controlled for age, race, and sex, smokers of low-yield cigarettes had a higher risk for pneumonia or influenza and chronic obstructive pulmonary disease when compared with subjects who had never used tobacco. We conclude that, with regard to pneumonia and influenza seen in an outpatient setting, smoking low-yield cigarettes is probably less hazardous than smoking high-yield cigarettes, but it still represents a considerable hazard compared with not smoking cigarettes at all.