AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Particle Size Characterization of a 4th Generation Electronic Cigarette Under Physiological Conditions
LANDON HOLBROOK, Elizabeth Monaghan, Chris Jadelis, Kirby Zeman, Robert Tarran, Ilona Jaspers, William Bennett, University of North Carolina at Chapel Hill
Abstract Number: 339 Working Group: Health Related Aerosols
Abstract In order to model the respiratory deposition of inhaled electronic cigarette (ECIG) aerosols, the mass median aerodynamic diameter (MMAD) should be determined by cascade impaction. Analytical models of respiratory deposition are a function of initial aerosol size and potential hygroscopic growth in the respiratory tract. To achieve physiologically realistic conditions in a 4th generation ECIG, a streamlined connector was designed and 3D printed to enable control of the relative humidity (RH) and temperature at the ECIG air inlet port. Methods: MMAD of the aerosol was measured within a Sierra Cascade Impactor at flows of 3, 14, and 21 liters per minute (LPM). The ECIG power was 100 Watts using a 0.25-ohm coil and the aerosolized liquid was either a commercial flavor containing 55% Propylene Glycol (PG) or 100% PG. Results: Decreasing the impactor flow rate affected the aerosol measurement of 55% PG; MMAD = 0.71, 0.85, and 1.55 µm at 21, 14, and 3 LPM respectively. The MMAD of 55% PG at 14 LPM was unchanged for ambient and 95% RH conditions. At ambient conditions, the MMAD of 100% PG was 1.05, 1.30, and 1.81 µm at 21, 14, and 3 LPM respectively. Conclusions: Particle sizing of ECIG aerosols by cascade impaction show fine particles of 0.7 – 1.4 µm MMAD are generated at realistic flows of 14 and 21 LPM. For a commercial ECIG with 55% PG the MMAD was unaffected by RH. The MMAD of the aerosolized 100% PG increased by 50% for realistic flows. Our data suggest that lung deposition of an aerosol generated by an ECIG is likely low (< 20% by deposition models) and occurs primarily in the alveolar region of the lung. The increased aerosol size associated with PG content may further enhance deposition throughout the respiratory tract. Supported by NIH/FDA 5P50HL120100.