At the 2018 Tobacco Science and Research Conference (TSRC), Holve D. et al presented results of a new light scattering instrument (Orion-A) for application to e-cigarettes without need for dilution. Orion-A provides automatic puff flow measurements based on measured pressure drop, display of complete size distribution, and size uncertainty estimation (typically 3-4 %) based on three independent scattering ratio measurements. Results have shown typical mass mean aerodynamic particle sizes in the range of 300 nm for liquid e-cigarettes (LECs), and 250 nm for heated and combustion cigarettes. Puff mass measurements are generally uniform in mass delivery for LECs over a series of puffs, while combustion and heated cigarette concentrations generally increase with puff sequence. A recent study (Sosnowski T.R. et al, 2018) highlights the importance of EC aerosol size distribution for respiratory regional deposition.

Current work focuses on extension of the Orion size range to include supermicron particle sizes, and effects of variable dilution and transport times. Orion-A uses angular MIE scattering DC signals to measure EC and combustion cigarette submicron aerosols. There is further interest in measuring the quantity (if any) of supermicron particles which would have an important impact on vapor transport. In addition to Orion-A, another measurement technique is under development, known as Variance Ratio (Orion-V), to measure larger particles in the size range of 1-100 microns, using the same optical instrument system as Orion-A. This method measures the RMS and DC scattering signals, which can be interpreted to give size and concentration. Results for nominal 5 micron nebulizer aerosols and larger sprays confirm the variance method measurement capability. Initial measurements of ECs show negligible contributions of supermicron vapors and that transport over variable distances have minimal impact on size and concentrations.