Stephens W E
School of Geography & Geosciences, University of St Andrews, St Andrews, Fife KY16 9AL, UK.
Tob Control. 2007 Jun;16(3):170-6. doi: 10.1136/tc.2006.017491.
To estimate the extent to which tar, nicotine and carbon monoxide (TNCO) yields are dependent on cigarette design features such as burn rate, filter ventilation and paper porosity, and to consider the implications for human exposure and the regulation of TNCO emissions. A related aim is to determine whether accurate prediction of TNCO yields is possible using only simple physical parameters.
Datasets that include quantitative design parameters as well as measurements of TNCO yields collected under standard conditions with vents unblocked (International Organization for Standardization) and under intense conditions with vents fully blocked (Health Canada) were compiled from the literature (primarily US and UK brands). Forward stepwise multiple regression analysis is used to assess the relative importance of each design feature in explaining variability in the observed emissions. Using randomly split data subsets, multiple linear regression is used to model the dependence of TNCO yields on design features in the training subset and validated against the test subset. Tar and carbon monoxide correlate with many of the particulate- and volatile-phase toxins in smoke, and brand values normalised to nicotine yield are used as surrogate measures of exposure within the bounds defined by non-intense and intense smoking protocols.
Filter ventilation is the dominant control on measured TNCO emissions, but other factors including burn rate, amount of tobacco and paper porosity also contribute. Yields are predictable with reasonable accuracy and precision using only measured physical parameters. Surrogate exposure indicators suggest that filter ventilation does not lead to any reduction in exposure and that highly ventilated (low-yield) brands may actually increase exposure to the more volatile toxins.
评估焦油、尼古丁和一氧化碳（TNCO）产量在多大程度上取决于香烟设计特征，如燃烧速率、过滤嘴通风和卷烟纸孔隙率，并考虑其对人体暴露及TNCO排放监管的影响。一个相关目标是确定仅使用简单物理参数是否能够准确预测TNCO产量。
从文献（主要是美国和英国品牌）中汇编数据集，这些数据集包括定量设计参数以及在通风口未堵塞的标准条件下（国际标准化组织）和通风口完全堵塞的强烈条件下（加拿大卫生部）收集的TNCO产量测量值。采用向前逐步多元回归分析来评估每个设计特征在解释观测排放变异性方面的相对重要性。使用随机划分的数据子集，多元线性回归用于对训练子集中TNCO产量对设计特征的依赖性进行建模，并在测试子集中进行验证。焦油和一氧化碳与烟雾中许多颗粒相和挥发性相毒素相关，以尼古丁产量标准化的品牌值用作在非强烈和强烈吸烟方案定义范围内的暴露替代指标。
过滤嘴通风是测量的TNCO排放的主要控制因素，但其他因素，包括燃烧速率、烟草量和卷烟纸孔隙率也有影响。仅使用测量的物理参数就能以合理的准确度和精密度预测产量。替代暴露指标表明，过滤嘴通风不会导致暴露减少，高度通风（低产量）品牌实际上可能会增加对挥发性更强毒素的暴露。
