Understanding the nicotine dose delivered by electronic nicotine delivery systems in a single puff: the importance of nicotine flux and puff duration.

Electronic nicotine delivery systems (ENDS) may lead to public health benefit if they help people who smoke quit smoking, and may lead to public health harm if they recruit a new generation of nicotine-dependent people. Regulators intent on maximising ENDS' public health benefit and minimising harm may be interested in regulating the nicotine dose delivered by ENDS in a single puff. The per-puff nicotine dose is the product of ENDS nicotine emission rate (or 'nicotine flux') and the duration of the puff taken by the person using the ENDS (or 'puff duration'). Nicotine flux can be measured or predicted mathematically for any ENDS device/liquid combination. Puff duration can be controlled electronically, as demonstrated by several ENDS marketed today. Combining nicotine flux and puff duration regulation is feasible today and provides authorities the means to limit nicotine dose per puff to a level that may help people who smoke quit smoking while reducing the possibility that nicotine-naive individuals will engage in repeated ENDS use. Tobacco regulatory science and product regulation will both be improved by a rigorous approach to understanding, characterising, and reporting the nicotine dose emitted by ENDS.