Some consequences of using cigarette machine smoking regimes with different intensities on smoke yields and their variability.

When smoking cigarettes under an intense regime with a combination of 100% ventilation blocking and high flow rates, as currently mandated by Health Canada, significant increases in filter temperatures and disproportionately high levels of mainstream smoke water and moisture accumulating in the spent filter were found when compared to other smoking regimes, especially for highly filter ventilated cigarettes. These effects have been reported to decrease cigarette firmness during the course of smoking, to alter filtration properties and efficiencies and to confound the measurement of particulate matter. The high filter temperatures generated also lead to significant amounts of vapour phase compounds desorbing from carbon filters and an over-estimation of the yields of these components. Less adsorption on or more desorption from carbon filters was found for compounds with the highest volatility. Therefore, yield data from the intense regime may not reflect the effectiveness of cigarette design features to reduce certain smoke components that occurs when products are smoked under conditions closer to those used by the majority of smokers in real world situations. In addition, a combination of these interacting factors may explain the worse level of between-laboratory reproducibility data for particulate matter measurement obtained during intense machine smoking. Among-laboratory data variability for vapour phase components, other than carbon monoxide, and for particulate phase components, other than nicotine, still needs to be evaluated in collaborative studies. Before proposing smoking regimes as tools to evaluate smoke emissions, it is essential to understand these various interacting factors and subsequent uncontrolled effects that such regimes can generate and the limitations of their use. These observations imply that higher tolerances may need to be set and taken into account when smoking under the intense regime before deciding that, for a given product, there are real differences between the yields determined in different laboratories.