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Characterization of Nanoparticles Emitted from Metallic Heaters in Electronic Cigarettes
KAUSHAL PRASAD, Mark D. Wilson, Jae Hong Park, Purdue University
Abstract Number: 548
Working Group: Nanoparticles and Materials Synthesis
Abstract
Electronic (e-) cigarettes, also known as electronic nicotine delivery systems, are battery-operated devices that are growing in popularity worldwide. The e-cigarette consists of a heater to vaporize nicotine solution, a reservoir that contains nicotine solution, and a wick to deliver the nicotine solution to the heater. When the heater is operating, metal vapor can be produced from its surface, cooled by air, and then form nanoparticles (<100 nm) through condensation and nucleation. Although e-cigarettes are known to be safer than traditional cigarettes, their potential health risks have not been extensively reviewed yet. In this study, nanoparticles generated from e-cigarette heaters were characterized based on the total number concentration (TNC) and the size of the particles. Four heater wires (Kanthal A1, Nichrome, stainless steel 316L, and titanium) were tested for 30 minutes with a frequency of 0.1 Hz and a 50% duty cycle (5s on, 5s off). The size distribution of particles emitted from each heater was measured using a scanning mobility particle sizer (SMPS). In all cases, the TNC of particles decreased over time because the oxidation layer on the coil surface prevented further nanoparticle emission. A used coil may reduce the risk of metal exposure from e-cigarettes. The initial number median diameter (NMD) and TNC of particles ranged from 40 nm to 80 nm and 1.0 – 3.5 × 107 particles/cm3, respectively. The resistance of the heater material affected the generation of nanoparticles. Particles from the titanium heater have the largest NMD and the highest TNC. Lower resistance materials may produce more particles since they have a longer length and larger surface area. These findings can be used for developing safer e-cigarettes.