APPLIED PHYSIOLOGY 4, April 1972. Printed in U.S.A. Number of alveoli in the human lung

total number of alveoli in the human lung is considerably more variable than is generally believed. We have found a mean value of 375 x lo6 and a range of 2 12-605 x lo6 with methods utilized by others. The total number of alveoli is positively correlated with body length. lung morphometry; alveolar surface area; stature; alveolar growth and multiplication RECENT EVIDENCE suggests that the total number of alveoli in the human lung is fairly constantly 300 X lo6 (6, 7, 17), although widely varying numbers have been reported in the older literature. (11, 18) While investigating the inter-nal (alveolar) surface area of nonemphysematous lungs, we found that the mean linear intercept (average interalveolar distance) was independent of body stature and lung volume (15). This suggested that the total number of alveoli mus