The Growth of Cigarette Smoke Particles Suspended on Fine Platinum Wire in Moist Air

The behaviour of smoke condensate (obtained from tobacco of Virginia type by electrostatic precipitation) and large smoke particles suspended on fine platinum wire was studied in moist air. The equilibrium vapour pressure of water over the surface of smoke condensate at 15°C was found to be 76.5 % of the saturation pressure, indicating that the apparent concentration of water soluble particulate matter in the smoke condensate is 1.2 × 10-3 g-mole g-1. The rate of growth of smoke particles suspended on fine wire in moist air was much slower than the rate predicted by Maxwell's theory. Apparently this is not caused by a rise in the temperature of the particle due to the heat liberated in the condensation process, but by a low value for the accommodation coefficient of the particle surfaces (1.5 × 10^-4). These results suggest that smoke particles of 0.4 AAµ in diameter, in transit through the respiratory system during smoking, grow by picking up water from the moist pulmonary air by a factor of only 1.7 in mass or 1.2 in diameter. It is concluded that this increase in size is not large enough to affect significantly the rate of deposition of smoke particles in the respiratory tracts.