“…There is now good evidence that this difference is associated with lower values for the transfer factor (diffusing capacity) for carbon monoxide measured by the single breath method (Billiet and Ulburghs, 1966;Lyons, Clarke, Hall, and Cotes, 1967;Cotes, Deivanayagam, Field, and Billiet, 1972). These changes constitute two components of the syndrome of defective gas transfer (Scadding, 1966), of which the third is hyperventilation during exercise.…”