Recruitment and flow of subjects within the study. A total of 72 subjects with specifically predefined smoking criteria (smoking ≥15 cig/day for at least 10 years) responded to the advert; of these, 9 subjects were not included in the study because they spontaneously seek assistance with quitting (these were then invited to attend the local smoking cessation clinic, which offers standard support with cessation counselling and pharmacotherapy for nicotine dependence). The remaining 63 subjects consented to participate into the study; of these, 13 were not considered eligible because of the exclusion criteria. In the end, 50 volunteers were included in the study and were issued with a second generation PV kit with a full supply of tobacco aroma e-liquid containing 9 mg/ml nicotine. By the end of the study, a total of 12 subjects were lost to follow-up due to failure of attending their control visits. Overall 38 participants were available for analyses at week-24 follow-up visit.