General ventilation systems control of environmental tobacco smoke

This investigation examined the effectiveness of ventilation systems in controlling environmental tobacco smoke (ETS). Three aspects of ventilation system effectiveness were studied: the consistency of the supply air distribution in a room, the use of macro-models to predict the air concentration of ETS, and the effect of the movement of people on the migration of ETS from a smoking section to a nonsmoking section of a room. Carbon monoxide, a tracer for ETS, was measured in test areas. The mixing factors in the test areas were calculated and used to evaluate the supply air distribution.; Investigation of the consistency of supply air distribution revealed that the mixing factors, {dollar}lambda ,{dollar} in the room varied with height, position, and air flow rate. While the magnitude of the difference between high and low positions was small, {dollar}<{dollar}10%, it was statistically significant. There was no significant difference in {dollar}lambda{dollar} between the locations within the high or low groups. The mixing factor at the position in the supply air plume was substantially greater than the values at the other 10 locations in the test chamber. At the higher air flow rate, {dollar}lambda{dollar} was significantly less than the values at the lower flow rates. No significant differences were detected between the means of {dollar}lambda{dollar} for experiments with different exhaust vent locations, carbon monoxide source (cigarette or gas cylinder), small changes in flow rate ({dollar}<{dollar}12%) or for duplicate experiments.; The use of macro-models to predict the air concentration of ETS required determination of contaminant generation rate and mixing factor terms. The mixing factors determined for the CO removal phase appeared to be applicable to this model. The inability of the model to predict the contaminant generation rate appeared to limit the utility of this model to estimate contaminant concentrations.; The movement of people did not appreciably affect the distribution and elimination of cigarette smoke. No ETS migrated from the smoking section to the nonsmoking section of the lunch room with or without people present. The presence of people resulted in only a slight change in the route followed by the ETS in the smoking section.