Particle Size Distribution of E-Cigarette Aerosols and the Relationship to Cambridge Filter Pad Collection Efficiency

Abstract

SUMMARYThe relatively volatile nature of the particulate matter fraction of e-cigarette aerosols presents an experimental challenge with regard to particle size distribution measurements. This is particularly true for instruments requiring a high degree of aerosol dilution. This was illustrated in a previous study, where average particle diameters in the 10-50 nm range were determined by a high-dilution, electrical mobility method. Total particulate matter (TPM) masses calculated based on those diameters were orders of magnitude smaller than gravimetrically determined TPM. This discrepancy was believed to result from almost complete particle evaporation at the dilution levels of the electrical mobility analysis. The same study described a spectral transmission measurement of e-cigarette particle size in an undiluted state, and reported particles from 210-380 nm count median diameter. Observed particle number concentrations were in the 10 9 particles/cm 3 range. Additional particle size measurements described here also found e-cigarette particle size to be in the 260-320 nm count median diameter range. Cambridge filter pads have been used for decades to determine TPM yields of tobacco burning cigarettes, and collection of e-cigarette TPM by fibrous filters is predicted to be a highly efficient process over a wide range of filtration flow rates. The results presented in this work provide support for this hypothesis.Described here is a study in which e-cigarette aerosols were collected on Cambridge filters with adsorbent traps placed downstream in an effort to capture any material passing through the filter. Amounts of glycerin, propylene glycol, nicotine, and water were quantified on the filter and downstream trap. Glycerin, propylene glycol, and nicotine were effciently captured (> 98%) by the upstream Cambridge filter, and a correlation was observed between filtration efficiency and the partial vapor pressure of each component. The present analysis was largely inconclusive with regard to filter efficiency and particle-vapor partitioning of water. [Beitr. Tabakforsch. Int. 26 (2014) 183-190] KEYWORDS: Electronic cigarette, aerosol, particle size, filtration efficiency ZUSAMMENFASSUNG Die relativ flüchtige Natur der Partikelfraktion von EZigaretten-Aerosol stellt hinsichtlich der Messungen zur Partikelgrößenverteilung eine experimentelle Herausforderung dar. Dies gilt im besonderen Maße für Geräte, die einen hohen Grad der Aerosolverdünnung erfordern. Dies wurde in einer vorangegangenen Studie dargestellt, in der die mittleren Partikeldurchmesser im Bereich von RESUMELa nature relativement volatile de la fraction de matière particulaire dans les aérosols de cigarettes électroniques représente un défi expérimental concernant les méthodes pour mesurer la distribution des tailles de ces particules. Cela est particulièrement vrai pour les instruments nécessitant un haut degré de dilution des aérosols. Ceci a été illustré dans une étude précédente, où une méthode de mobilité électrique à dilution élevée a permis de...

A scattering methodology for droplet sizing of e-cigarette aerosols

“…As a result, the aerosol was drawn in the cylinder housing of the PDSP piston for a puff duration of 2 s. The aerosol was immediately exhausted from the PDSP housing by the action of the piston pushing off the aerosol for a duration of 1.4 s to two TSI aerosol diluters to recover 1/10 000 of the aerosol concentration and ensuring droplets could enter one by one into the LAS detector. Indeed, although the TSI diluter should minimize droplet evaporation, e-cigarette aerosol is generally highly volatile as highlighted in other work (Alderman at al., 2014;Ingebrethsen et al, 2012;Mikheev et al, 2016;Schripp et al, 2013) and may trigger droplet size change prior to a measurement is performed. Furthermore, use of the PDSP pump increased the aerosol residence time by at least 3.4 s prior to measurement.…”

Real-Time Measurement of Electronic Cigarette Aerosol Size Distribution and Metals Content Analysis

“…The upper size limit of the DMS500 could be extended up to 2.5 microns, thus other methods, such as the cascade impactor, 28 should be applied for the larger size particles analysis to complement DMS500 measurements.…”

“…The cascade impactor method (with the lowest cut-point 56 nm) was also recently applied. 28 These studies concluded that the particles in e-cigarette aerosols are similar in size to combustible tobacco smoke submicron particles; however, recent measurements that used an advanced real-time technique at low sample dilution showed a high number concentration of nanoparticles generated by e-cigarettes along with a comparable concentration of the submicron particles. 27 The presence of nanoparticles in e-cigarette aerosol was previously reported, 10 although real-time analysis of the aerosol size distribution was not conducted.…”

Thermodynamic and kinetic behavior of glycerol aerosol

“…The volatility of the aerosol constituents combined with the high number concentration has led to uncertainty in the nature of the e-cigarette plume number and size distributions. Electronic cigarettes produce aerosol number concentrations on the order of »10 9 cm ¡3 particles with a mean diameter ranging from »100 to 600 nm (Ingebrethsen et al 2012;Fuoco et al 2014;Alderman et al 2015). The short particle lifetime, variability between devices from different manufacturers, and different measurement methods are possible explanations for the differing size distributions (Ingebrethsen et al 2012).…”

“…The short particle lifetime, variability between devices from different manufacturers, and different measurement methods are possible explanations for the differing size distributions (Ingebrethsen et al 2012). Optical (Ingebrethsen et al 2012), gravimetric (Alderman et al 2015), and electrical mobility (Fuoco et al 2014) measurement techniques have been employed to measure electronic cigarette aerosol size distributions. However, these measurements did not account for particle evaporation.…”