Mouth Insertion Depths in Canadian Smokers

There is the potential for smokers of ventilated cigarettes to block the ventilation holes either accidentally or deliberately thereby altering the smoke deliveries from those obtained by standardized machine smoking. One way in which the holes can be blocked is by inserting the cigarette into the mouth so that the holes are partially or completely blocked by the lips of the smoker. We have assessed to what extent this occurs amongst Canadian smokers by measuring the saliva patterns on 2756 cigarette butts collected in Montreal, Toronto and Vancouver. The butts were a cross-section of brands smoked in Canada. Saliva stains were visualized by treating the tipping paper with ninhydrin solution. The insertion depth was assumed to be the maximum extent of the saliva stain from the mouth end of the tipping. The brand of each cigarette butt was identified where possible as well as whether the filter was ventilated and if so, the distance of the vent holes from the mouth end. The butt lengths were also determined. Of the 2756 butts collected, 2232 had lip imprint patterns that could be visualized with ninhydrin solution. 56.2 % of the butts with measurable insertion depths, and which could be identified by brand, were ventilated. There was no significant difference between the average insertion depths for ventilated and non-ventilated brands (10.6 AA± 3.6 and 11.0 AA± 3.6 mm respectively). It was estimated that for the ventilated brands between 3.7-10.3 % of the butts could have had the vents blocked completely for at least one puff, 13.8-20.4 % of the butts had vents that could have been partially blocked and 75.9 % of the butts showed no sign of any vent blockage during smoking.