Chapter 10 
Table 5 
Influence of ventilation on machine yields 
Yield per Cigarette (mg) 
Percent Blockage 
Brand 
(ventilation) 
Constituents 
0 
50 
100 
A (55%) 
Tar 
3.8 
5.9 
10.0 
Nicotine 
0.46 
0.55 
0.82 
Carbon monoxide 
3.8 
6.0 
12.7 
B (35%) 
Tar 
9.2 
10.6 
12.8 
Nicotine 
0.90 
0.90 
0.98 
Carbon monoxide 
9.2 
10.9 
15.2 
Source: Darrall, 1988. 
including nonfilter, were taped. Nonfilter cigarettes and filter cigarettes 
with little or no ventilation were seen to be only slightly affected by the 
tape. Some effect would be expected for nonfilter cigarettes because taping 
blocks air flow through the cigarette paper, but the changes observed were 
barely statistically significant for the experimental design used. The effect 
on ventilated filter cigarettes (VF-A to VF-F in Figure 1) was significant and 
major. Products rated as FTC 1 mg tar yielded 5 mg or more of tar when 
the ventilation was completely occluded. Products rated at 2 to 4 mg of 
tar delivered up to 10 mg of tar. In the case of brand F-F, the substantial 
increase in delivery when cigarettes were taped suggested that the filter 
incorporated ventilation even though it was not obvious from visual 
inspection. Trends for nicotine and carbon monoxide yields were generally 
parallel to those for tar. 
INFLUENCE OF Standardized machine smoking was developed to ensure that 
HUMAN SMOKING differences in yields among cigarettes were caused by the nature 
PRACTICES of the cigarettes and not by differences in the measurement 
method. The FTC adopted standardized machine smoking to maximize 
its ability to discriminate accurately among brands. The FTC test has been 
successful for this purpose but is accurate only where cigarettes are smoked 
as prescribed by the method. 
The relevance of the FTC test parameters to human smoking practices 
has been called into question as FTC ratings have increasingly been viewed 
as a measure of human exposure. This concern is heightened by the 
increasing popularity of low-tar and ultralow-tar products relying largely 
on filter ventilation and by a better understanding of compensatory smoking 
practices. Observation of more recent smoking practice showed that filter 
ventilation was commonly compromised, puff volume was somewhat greater 
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