Inclusion Criteria:

• * Heart rate \< 105 beats per minute (BPM)\*
• * Systolic Blood pressure \<160 and \> 90\*
• * Diastolic Blood Pressure \<100 and \> 50\*
• * Body Mass Index (BMI) \< 38.0 (at investigator's discretion for higher BMI if no other concurrent health issues)
• \*considered out of range if both machine and manual readings are above/below these thresholds
• * Use e-cigarettes on at least 15 days in the past 30 for at least 3 months
• * Smoke 10 or fewer cigarettes/tobacco products per day in the last 30 days
• * Willing to use mod e-cigarette
• * Willing to abstain from tobacco product use for night before study
• * Age: \> 21 years old and \< 70 years old
• * Using e-liquid \> 0mg/ml nicotine
• * Saliva cotinine of ≥ 30 ng/ml or NicAlert=6 (in cases where lab turn around time will delay study procedure)

Exclusion Criteria:

• * Seizures
• * Cancer
• * Hepatitis B or C or Liver Disease
• * Oral Thrush
• * Heart disease
• * Glaucoma
• * Kidney disease or urinary retention
• * Diabetes
• * High Blood Pressure (taking sympatholytic medications such as alpha and beta blockers)
• * History of stroke
• * An ulcer in the past year
• * Thyroid disease (okay if controlled with medication)
• * Active use of an inhaler for asthma or Chronic Obstructive Pulmonary Disease (COPD)
• * Psychiatric conditions
• * Current or past schizophrenia, and/or current or past bipolar disorder
• * Major depression, current or within the past year
• * Major personality disorder
• * Participants with current or past minor or moderate depression and/or anxiety disorders will be reviewed by the study physician and considered for inclusion.
• * History of psychiatric hospitalizations are not exclusionary, but study participation will be determined as per study physician's approval
• * Recent onset or change in cough, fever and/or abdominal symptoms (vomiting or pain) in the past two weeks. (If yes, participant can re-screen when symptoms resolve).
• * Drug/Alcohol Dependence
• * Alcohol or illicit drug dependence within the past 12 months with the exception of those who have recently completed an alcohol/drug treatment program
• * Positive toxicology test at the screening visit (THC \& prescribed medications okay)
• * Opioid replacement therapy (including methadone, buprenorphine, or other)
• * Positive urine cannabis is not exclusionary but participant must report use of cannabis and agree to abstain from cannabis use for the duration of the study
• * Psychiatric medications
• * Current regular use of any psychiatric medications with the exception of Selective Serotonin Reuptake Inhibitor (SSRI) and serotonin-norepinephrine reuptake Inhibitor (SNRIs) and current evaluation by the study physician that the participant is otherwise healthy, stable, and able to participate.
• * Medications
• * Use of medications that are inducers of nicotine metabolizing enzyme CYP2A4 (Example: rifampicin, carbamazepine, phenobarbital, and other anticonvulsant drugs).
• * Concurrent use of nicotine-containing medications
• * Any stimulant medications (example: Adderall) generally given for Attention deficit hyperactivity disorder (ADHD) treatment
• * Use of sympatholytic medications that affect cardiovascular conditions including hypertension, (Example: beta and alpha-blockers)
• * Other/Misc. Chronic Health Conditions
• * Fainting (within the last 30 days)
• * Other "life threatening illnesses" as per study physician's discretion
• * Pregnancy
• * Pregnancy (self-reported and urine pregnancy test)
• * Breastfeeding (determined by self-report)
• * Concurrent participation in another clinical trial
• * Inability to communicate in English
• * Planning to quit vaping within the next 60 days
• * Uncomfortable with getting blood drawn