Regional deposition of particles in the lung during cigarette smoking in humans.

Studies were carried out on 11 habitual cigarette smokers to ascertain whether there was a difference in the regional deposition of particles during cigarette smoking compared with tidal breathing and also to investigate whether the ventilatory maneuvers associated with smoking influence the deposition site. A cigarette holder was constructed that permitted cigarette smoke to mix with a radioaerosol. An added resistance simulated the airflow resistance present in a filter-tipped cigarette. Respiratory patterns for the control period of tidal breathing and during smoking were monitored with a respiratory inductance plethysmograph. Smoking resulted in greater apical and central deposition than expected from the distribution of resting ventilation. The changes in the site of deposition during smoking are probably influenced mainly by the properties of the particles concerned, namely, its size, reactivity, and hygroscopicity. Changes in respiratory patterns that occur during inhalation of cigarette smoke may also have an effect but are difficult to quantify and show marked intersubject variation. In selected subjects smoking caused apical deposition to exceed that of the lower zones.