Tests of pulmonary function and radiographic imaging of the chest are the two key methods used in diagnostic evaluation of patients with pulmonary disease. Unlike blood pressure, acceptable normal values vary from person to person and from one demographic group to another. The first studies, in 1846, of spirometric assessment of forced vital capacity (FVC), the most basic pulmonary-function test, showed that normal values for vital capacity vary as a function of height and age.1 A few years later, it was shown that vital capacity was 6 to 12% lower in healthy black soldiers than in white or Native American . . .