ABSTRACT
BACKGROUND: Smoking is closely related to pulmonary diseases, especially pulmonary function. Past studies were defective in that pulmonary function was not included for ex-smokers and the study population being too small. This study attempted to show the change of pulmonary function parameters according to post-smoking years of ex-smokers and pack-years of current smokers. METHODS: We analyzed the results of parameters derived from the forced expiratory spirogram in 3,713 adults who visited Kyungpook National University Hospital Health Screening Center between May 1997 and March 1998. Independent variables used were age, sex, height, weight and smoking status. Dependent variables were pulmonary function parameters. Multiple regression analysis was used. RESULTS: 1.Overall, there was a significant change in pulmonary function parameters among the subjects studied. Significant variables shown were age, sex, height and pack-years. Weight and post-smoking years turned out to be relatively less significant variables. 2. Positive correlation was seen in both FEV1/FVC and FEF25-75% in ex-smokers with longer post-smoking years. 3. There was negative correlation in all the parameters of current smokers with longer pack-years. CONCLUSION: The results of this test show that smoking slowly reduce pulmonary function and even those smokers who quit smoking can not be expected to have normal pulmonary function as healthy nonsmokers. However, ex-smokers can expect some improvement in certain pulmonary function parameters as the post-smoking years become longer.