Introduction: Cigarette smoking causes devastating disease worldwide. Current cigarette classification is based on standardised tar mass values obtained from smoking-machines. However, their ability to predict disease is poor, and these mass values are primarily determined by larger particles. The aim of our study is to investigate in how far claimed tar values also reflect smaller tar particles in cigarette smoke.
Methods: We developed a method to measure size-resolved particle distributions based on experimentally selecting conditions that revealed the least variety within different smoking regimes, puff numbers, diluted and undiluted ageing times, and filter taping. Next, we analysed three cigarettes types with different tar values. Cigarettes were smoked by a Cerulean SM-450 smoking machine, and subsequently smoke samples were diluted and collected in Tedlar® bags and measured for size-resolved particle distributions by a universal optical aerosol spectrometer.
Results: Our method involved a smoking regime according to ISO 3308, the sixth puff, and no delayed ageing. We attained valid size-resolved particle distributions between 250 and 1,000 nm. The results revealed similar total particle counts across different cigarette types, though with different size-resolved particle distributions. In particular, smaller particles in lower tar cigarettes were underestimated.
Conclusion: We developed a method to investigate submicron size-resolved particle distributions in cigarette smoke in order to compare cigarettes with different tar values. Our study suggests that mass-based tar values are a poor reflection of smaller particles in mainstream cigarette smoke, and hence supports the opinion that current tar values are a poor predictor of disease-risk and therefore that they are deceptive to smokers.