Caner U. Yurteri

Assessment of novel tobacco heating product THP1.0. Part 3: Comprehensive chemical characterisation of harmful and potentially harmful aerosol emissions

ABSTRACT For a tobacco heating product (THP), which heats rather than burns tobacco, the emissions of toxicants in the aerosol were compared with those in cigarette smoke under a machine‐puffing regimen of puff volume 55 ml, puff duration 2 s and puff interval 30 s. The list of toxicants included those proposed by Health Canada, the World Health Organization Study Group on Tobacco Product Regulation (TobReg), the US Food and Drug Administration and possible thermal breakdown products. In comparison to the University of Kentucky 3R4F reference cigarette the toxicant levels in the THP1.0 emissions were significantly reduced across all chemical classes. For the nine toxicants proposed by TobReg for mandated reduction in cigarette emissions, the mean reductions in THP1.0 aerosol were 90.6–99.9% per consumable with an overall average reduction of 97.1%. For the abbreviated list of harmful and potentially harmful constituents of smoke specified by the US Food and Drug Administration Tobacco Products Scientific Advisory Committee for reporting in cigarette smoke (excluding nicotine), reductions in the aerosol of THP1.0 were 84.6–99.9% per consumable with an overall average reduction of 97.5%. HighlightsTHP1.0, which heats rather than burns tobacco, was compared with 3R4F cigarette.Harmful and potentially harmful constituents were measured in the aerosols and compared.Toxicants in the aerosol of THP1.0 were substantially lower than in 3R4F smoke.Reduction averaged 96.1 per cent for nine substances prioritised for lowering in cigarettes.Reduction averaged 96.8 per cent for 18 substances prioritised by the US FDA.

Component-specific, cigarette particle deposition modeling in the human respiratory tract

Abstract Inhalation of cigarette smoke particles (CSP) leads to adverse health effects in smokers. Determination of the localized dose to the lung of the inhaled smoke aids in determining vulnerable sites, and identifying components of the smoke that may be responsible for the adverse effects; thus providing a roadmap for harm reduction of cigarette smoking. A particle deposition model specific to CSP was developed for the oral cavity and the lung by accounting for cigarette particle size growth by hygroscopicity, phase change and coagulation. In addition, since the cigarette puff enters the respiratory tract as a dense cloud, the cloud effect on particle drag and deposition was accounted for in the deposition model. Models of particle losses in the oral cavities were developed during puff drawing and subsequent mouth-hold. Cigarette particles were found to grow by hygroscopicity and coagulation, but to shrink as a result of nicotine evaporation. The particle size reached a plateau beyond which any disturbances in the environmental conditions caused the various mechanisms to balance each other out and the particle size remain stable. Predicted particle deposition considering the cloud effects was greater than when treated as a collection of non-interacting particles (i.e. no cloud effects). Accounting for cloud movement provided the necessary physical mechanism to explain the greater than expected, experimentally observed and particle deposition. The deposition model for CSP can provide the necessary input to determine the fate of inhaled CSP in the lung. The knowledge of deposition will be helpful for health assessment and identification and reduction of harmful components of CSP.

Steady-state mass-mobility measurements of cigarette smoke using a CPMA

Tobacco smoke is a dynamic formation of gaseous and particulate material. The density of particulate phase can change due to evaporation condensation and alter its mass and mobility. Therefore these aerosol characteristics are important for modelling lung deposition or smoke particle transport in air. The mass and mobility of cigarette smoke particles was measured using a Centrifugal Particle Mass Analyzer (CPMA) and Differential Mobility Analyzer (DMA). The experimental setup, shown in Figure 1, placed a DMA and Condensation Particle Counter (CPC) upstream of a CPMA. The DMA selected the particles based on electrical mobility, while the upstream CPC accounted for the particle concentration decreasing in the bag over time. The CPMA then further classified the particles by mass-to-charge ratio. By stepping the CPMA through the particle mass range and counting the number of classified particles with the downstream CPC the mass-classified concentration peak was determined for the set DMA mobility size.

Physical aerosol characterisation of e-cigarettes

For each formulation variant (Table 1) fifteen puffs were completed for measurement, on three independent devices. Thus, n=45 for each variant using each measurement method. The formulation reservoir was driven toward depletion by firing to waste for forty puffs after every five DSD measurements. Gravimetric measurements were recorded after every sizing puff and waste puff series. The average mass loss per puff was therefore calculated on an n=95 basis.

CFD simulations of mainstream cigarette smoke particle growth and deposition in the oral airways

CFD Model • A 3D computational fluid dynamics (CFD) model of the mouth-throat region was developed from CT scans (Fig. 1) • Steady-state airflow was simulated for low-flow puffing scenarios (1.05 and 2.5 L/min) (Fig. 2) [2] • Transport and deposition of inhaled 0.1 – 0.5 μm particles was simulated • Lagrangian particle tracking was used to simulate deposition by inertial impaction, sedimentation, and diffusion • All CFD analyses were conducted using Fluent v14.0 (ANSYS, Inc.)