Relation of smoking and age to findings in lung parenchyma: a microscopic study.

A microscopic study was made to determine the relationship between various lung parenchymal changes, smoking habits and age. The subjects were 1,824 men and women for whom a macroscopic study of pulmonary emphysema has previously been reported. Lung parenchymal changes included rupture of alveolar septa (emphysema), fibrasis, and thickening of small arteries and arterioles. The mean degree of each of these pathologic cbanges increased with age and was far greater in cigarette smokers than in nonsmokers. The mean degree of emphysema increased from 0.09 in men who never smoked, to 1.43 in those who smdred less than one half pack per day, to 2.27 for 2+ packs per day smokers. The mean degree of fibrosis was 40 times as high in 2+ packs per day smokers as for men who never smoked. The degree of thickening of arterioles and arteries showed the same pattern by smoking habits. Cigar and pipe smokers had patbe logic changes that were greater than for men who never smoked, but less than for cigarette smokers. Former smokers who had given up smoking cigarettes for more than ten years had lesser degrees of pathologic changes than those who had given up cigarettes for less than ten years. The patterns of changes for the 388 women in the study were essentially the same as for men.