Smoking Habits and the Leukocyte Count

In 86,488 multiphasic examinations, mean leukocyte counts were highest in cigarette smokers, intermediate in ex-cigarette and cigar or pipe smokers, and lowest in nonsmokers. Among the races, whites had the highest, yellows next, and blacks the lowest leukocyte counts. The leukocyte count was related to quantity smoked, inhalation, and smoking duration. Most groups who changed smoking habits showed corresponding changes in leukocyte counts. Higher leukocyte counts in smokers appeared largely to be a direct effect of smoking, although a small part of the increase seemed attributable to chronic bronchitis. A contribution of genetic or constitutional differences between smokers and nonsmokers was not ruled out. “Normal” leukocyte count values should take into account age, sex, race, and smoking status.