Physical characterization of the aerosol of an electronic cigarette: impact of refill liquids.

Electronic cigarettes are used to evaporate a mixture of solvents, nicotine and flavors. Liquid particles can be generated under these conditions due to evaporation/condensation. The objective of this work is to measure the physical characteristics of the aerosol emission of an e-cigarette using different refill liquids. The aerosol particle number and size are determined with a Scanning Mobility Particle Sizer. Seven liquids are used: propylene glycol (PG), glycerol (VG), a mixture 1:1 of PG/VG, the mixture with 2% or 5% of a commercial flavor, the mixture with 1.2% of nicotine and the mixture with 1.2% of nicotine and 2% of flavor. Particle concentrations of the aerosol emitted from the electronic cigarette are 300-3000 times higher than that of the ambient air. Propylene glycol emits several times more than glycerol. The addition of a flavor or nicotine has little effect on the emission of the total number emitted. The count median diameter of the electronic cigarette particles is 200-400 nm, depending on the liquid used. Count median diameter of emitted particles is affected by the liquid used.