Selective venting of cigarette smoke in dichotomous ducts and preserved human bronchi.

Mechanically generated cigarette smoke and ambient air were injected into dichotomous ducts and geometrically preserved human bronchi in a fashion simulating typical smoking technique. When the air passages were at ambient temperature, the smoke settled into the lower branches. Smoke which was injected into passages warmed to body temperature rose to the upper branches. The latter selective distribution of the smoke resembled the distribution of centrilobular emphysema in the lungs.