PREDICTING REGIONAL LUNG DEPOSITION OF ENVIRONMENTAL TOBACCO-SMOKE PARTICLES

Inhalation exposure to environmental tobacco smoke (ETS) particles may increase health risks, but only to the extent that the particles depo sit in the respiratory tract. We describe a technique to predict regio nal lung deposition of environmental tobacco smoke particles. Interpre tation of particle size distribution measurements after cigarette comb ustion by a smoking machine in a test room yields an effective emissio ns profile. An aerosol dynamics model is used to predict indoor partic le concentrations resulting from a specified combination of smoking fr equency and building factors. By utilizing a lung deposition model, th e rate of ETS mass accumulation in human lungs is then determined as a function of particle size and lung airway generation. Considering emi ssions of sidestream smoke only, residential exposures of nonsmokers t o ETS are predicted to cause rates of total respiratory tract particle deposition in the range of 0.4-0.7 mug/day per kg of body weight for light smoking in a well-ventilated residence and 8-13 mug/day per kg f or moderately heavy smoking in a poorly ventilated residence. Emission s of sidestream plus mainstream smoke lead to predicted deposition rat es about a factor of 4 higher. This technique should be useful for eva luating health risks and control techniques associated with exposure t o ETS particles.