Clinical Research Directory

Inclusion Criteria: * Being male or female between the ages of 22-55; * Being able to read and write in English and understand and give informed consent; * Giving consent to strictly follow the study protocol throughout the study; * Not planning to move, take an extended vacation, or undergo surgery during the study; * Reporting smoking of \> 5 manufactured cigarettes per day for at least 1 year (applicable to participants who will undergo intervention with e-cig (Grp 1) or continue to smoke (Grp 2) only); and * Presenting with an expired air CO measurement of \> 7 parts per million (ppm) at baseline (applicable to participants who will undergo intervention with e-cig (Grp 1) or continue to smoke (Grp 2) only). Exclusion Criteria: * Having oral infection/inflammation, gum disease, dental decay, immune system disorders, diabetes, respiratory diseases (e.g., asthma), or kidney diseases; * Having any unstable or significant medical condition (e.g., symptomatic heart conditions) in the past 12 months ; * Having body mass index \< 18 kg/m2 or \> 40 kg/m2 * Being pregnant or having a baby in the past 12 months; * Having uncontrolled mental illness or substance abuse (e.g., alcoholism) or inpatient treatment for those conditions in the past 12 months; * Having used recreational or illicit drugs in the past 3 months; * Having used any medication known to induce/inhibit CYP450 2A6 enzyme; * Having any known allergy to propylene glycol/vegetable glycerin (applicable participants who will undergo intervention with e-cig (Grp 1) only); and * Having another member of household participating in the study.