Inclusion Criteria:  Female and male, aged 21 to 55 years; past year daily cigarette use, verified by urine cotinine levels above 100 ng/ml -lifetime history of e-cigarette use; in good health as verified by medical history -screening examination, and screening laboratory tests women, -using acceptable birth control methods.  Exclusion Criteria:  History of major medical or psychiatric disorders that the physician investigator deems as contraindicated for the participant to be in the study risk factors for EVALI (E-cigarette or Vaping Product Use-Associated Lung Injury) including history of lung diseases (e.g., asthma or COPD), vaping THC or CBD regular use of psychotropic medication (antidepressants, antipsychotics, or anxiolytics) current alcohol or substance use disorder for any other recreational or prescription drugs other than nicotine for women, pregnant as determined by pregnancy screening, or breast feeding seeking (or undergoing) treatment for tobacco dependence or smoking; reported aversion to e-cigarettes, or tobacco flavored e-liquid.