Variability of Electronic Cigarette Particle Size Distributions and the Effects of Background Air

In the last few years, electronic cigarettes have been increasing in popularity, especially with younger people and people attempting to quit smoking. However, little is known about the various factors that affect the effluent from these devices. E-cigarettes are powered by a battery that heats up filament which in turn heats up a wick and converts the e-liquid into vapor that is then inhaled by the user. The e-liquids are composed of propylene glycol, glycerin, varying flavor agents, and a range of nicotine concentrations. The main goals of this research project are to identify factors which affect the size distribution of particles in the effluent. The factors we are examining include the relative humidity of the feed air, the concentration of particles in the feed air and in the environment that effluent immediately mixes with as well as the heating voltage and the composition of the e-liquid.

The nicotine content in the gas phase increased with an increase in power to the e-cigarette, but in general the majority of the nicotine was found in the particulate phase. The common range for e-cigarette operation today is between three and five volts, and there was a greater nicotine content that was found when operating the e-cigarette at the higher end voltage. This research produced data that showed the different varieties of e-cigarettes produced bimodal distributions of aerosol particle sizes, which is associated with the different boiling points of the different liquid components.