Nicotine and cigarette smoking: an alternative hypothesis.

A new hypothesis is presented to explain some aspects of human smoking behaviour. While acknowledging the importance of the nicotine self-titration phenomenon, changes in puffing intensity during the smoking of a single cigarette are related not to the control of nicotine uptake but to the modification of cigarette smoke composition prior to inhalation. It is suggested that nicotine, in addition to its central effects, has the local action of reducing the acute airway response to irritant components of cigarette smoke. The new hypothesis explains some of the 'anomalous' results of smoking behaviour research, and has implications both for cigarette design and for the recommendations made to smokers by statutory health agencies.