Smoking and Tobacco Control Monograph No. 7 
DR. RICKERT: Do you feel that this blocking is something that we should be 
concerned about? 
DR. ZACNY: Yes. 
DR. SHIFFMAN: One of the issues that you raised that we have not discussed 
much is variability within a given smoker, due to brand switching, for 
example. Can you give us some quantitative estimates of the degree of 
variability? 
DR. ZACNY: 1 believe Dr. Stitzer would be the best person to answer this 
question. 
DR. STITZER: In one example, it was shown for deprivation to be 10 to 
15 puffs. And that makes quite a big difference when you multiply it by the 
puff volumes, leading to a substantial difference in cumulative puff volume. 
DR. HATSUKAMl: Also, one subject after meals typically took about eight 
puffs per cigarette, whereas on the telephone, they would take about five 
puffs from the cigarette. 
DR. TOWNSEND: Dr. Zacny, 1 am a bit confused about the whole blockage 
question. Is the measure that you used to determine hole blockage just the 
staining at the mouth end of the filter? 
DR. ZACNY: Yes. Different cigarettes have different types of what we call 
tipping and different types of perforations. The perforations differ largely 
in the number of holes and the size of those holes. 
Those parameters of ventilation, in fact, determine to a large degree the 
staining pattern in the first place. So, it is possible to make a highly air- 
diluted cigarette with many ventilation holes that are very small and, in 
fact, see relatively uniform staining patterns right at the mouth end of the 
cigarette. 
If you are interpreting that as vent blocking, then 1 think that is probably 
an incorrect conclusion, because of the design of that specific filter. Filters 
with large though very few holes will tend to force the smoke to the center 
of the filter, and you will see that bullet shape right at the mouth end that 
was shown in one of the slides. 
Fhe concern is that not all cigarettes are built in the same way and so 
that it is probably a bit premature to conclude that there is vent blocking 
solely on the basis of filter observation. 
DR. STITZER: The data that were presented in this talk showed what 
happened to smoke exposure when the vents were experimentally blocked 
with tape. Dr. 'I'ownsend is asking a different kind of question about 
measurement of blocking in the natural environment. 
DR. I'OWNSEND: So, these were not with actual subjects, then? 
DR. S'n rZER: Fhey were with natural subjects, but we blocked the vents. 
