[Modifications in the closing volume due to the inhalation of tobacco smoke]

Two methods, the one making use of nitrogen and the other of body plethysmography were applied to a group of normal young subjects in order to value the effects of the inhalation of tobacco smoke on the "closing volume". The results obtained with the two methods are different; according to authors, this phenomenon may be explained on the base of the physiopathologic meanings of the closing volume, under the condition to admit that tobacco smoke may promote an early closure and before all disorders in the distribution of the residual volume.