Certain ENDS are reusable, tanks are refilled and atomisers changed when required. Although there are many published studies describing emissions of ENDS, the majority do not make assessments following multiple refills and it is not known if user detectable signs of failing atomizers relate to increases in potentially harmful carbonyls. This study aims to provide insight into flavour changes and emissions over multiple refills whilst reusing the atomizer.

Two tobacco flavoured formulations have been assessed; one contains sugars (A) the other does not (B). An unflavoured control is being assessed at the time of writing. Tasting using a flavour wheel as a guide was carried out, whilst aerosol mass, carbonyls, and nicotine emissions were also assessed. Puffs to waste were carried out to drain the tank in between refills. Tasting and emissions measurement was then repeated. Aerosols were generated using CORESTA Recommended Method (CRM) No. 81 modified with a five second puff duration. Seven tank fills were completed for both flavours. No trends were observed for nicotine and aerosol mass measures. Mean formaldehyde increased for both flavours, 1.4 to 4.4 µg/10 puffs and 1.3 to 25 µg/10 puffs in A and B respectively. Acetaldehyde, acrolein, and propionaldehyde showed similar trends, no crotonaldehyde or butyraldehyde were detected. When tasted over the course of numerous refills, flavour A changed, with more incidences of “burnt” taste occurring at refill 5 onwards; the burnt description was accompanied by a majority of tasters indicating atomizer replacement at this point. Flavour B changed subtly throughout seven refills however fewer “burnt” tastes were recorded compared to A. Also, tasters did not record a clear indication to replace atomizers compared to A. Changes in ENDS flavour profile are detectable by users; this flavour change is not linked to threshold levels of carbonyls.