Emissions from electronic cigarettes. Part 1: Key parameters affecting the release of harmful chemicals

M. SLEIMAN; J.M. LOGUE; V.N. MONTESINOS; M.I. LITTER; L.A. GUNDEL; H. DESTAILLATS

Environmental Science and Technology

ACS

Año: 2016 vol. 50 p. 9644 - 9651

Use of electronic cigarettes has grown15 exponentially over the past few years, raising concerns about16 harmful emissions. This study quantified potentially toxic17 compounds in the vapor and identified key parameters18 affecting emissions. Six principal constituents in three different19 refill ?e-liquids? were propylene glycol (PG), glycerin, nicotine,20 ethanol, acetol, and propylene oxide. The latter, with mass21 concentrations of 0.4−0.6%, is a possible carcinogen and22 respiratory irritant. Aerosols generated with vaporizers23 contained nicotine, nicotyrine, formaldehyde, acetaldehyde,24 glycidol, acrolein, acetol, and diacetyl. Glycidol is a probable25 carcinogen not previously identified in the vapor, and acrolein26 is a powerful irritant. Emission rates ranged from tens to27 thousands of nanograms of toxicants per milligram of e-liquid vaporized, and they were significantly higher for a single-coil vs a28 double-coil vaporizer (by up to an order of magnitude for aldehydes). By increasing the voltage applied to a single-coil device29 from 3.3 to 4.8 V, the mass of e-liquid consumed doubled from 3.7 to 7.5 mg puff−1 and the total aldehyde emission rates tripled30 from 53 to 165 μg puff−1, with acrolein rates growing by a factor of 10. Aldehyde emissions increased by more than 60% after the31 device was reused several times, likely due to the buildup of polymerization byproducts that degraded upon heating. These32 findings suggest that thermal degradation byproducts are formed during vapor generation. Glycidol and acrolein were primarily33 produced by glycerin degradation. Acetol and 2-propen-1-ol were produced mostly from PG, while other compounds (e.g.,34 formaldehyde) originated from both. Because emissions originate from reaction of the most common e-liquid constituents35 (solvents), harmful emissions are expected to be ubiquitous when e-cigarette vapor is present.