Evaluating the Comparative Pharmacokinetics of Nicotine After Administration Via JUUL or Tobacco Cigarettes

Inclusion Criteria: * Healthy on the basis of medical history and limited physical examination, as described below: * \- Heart rate \< 105 beats per minute (bpm) * \- - Considered out of range if both machine and manual readings are above/below these thresholds. * \- Systolic Blood Pressure \< 160 and \> 90\* * \- Diastolic Blood Pressure \< 100 and \> 50\* * Age: \>= 21 \& \<=70 years old * Body Mass Index (BMI) \<= 38.0 (at PI's discretion for higher BMI if no other concurrent health issues) * Willingness to avoid combusted marijuana up to 48 hours before each study visit * Nicotine strength of e-liquid of usual e-cigarette \> 0 mg/ml * Group 1 Experienced E-cigarette users * \- Current use of tobacco cigarettes (\<5 cigarettes per day) * \- Current e-cigarette use at least 15 days out of the past 30 days of a non-mod e-cigarette * Group 2 Primary Tobacco cigarette users: * \- Currently smoking \>= 5 cigarettes per day * \- Current e-cigarette use must be \< 5 times per month * Saliva cotinine \>=50 ng/ml or urine cotinine and/or NicAlert=6 * Must have a smart phone, computer, or tablet and internet access (for remote procedures) Exclusion Criteria: * Medical * \- Heart disease * \- Seizures * \- Cancer * \- Thyroid disease (okay if controlled with medication) * \- Diabetes * \- Hepatitis B or C or Liver disease * \- Glaucoma * \- Kidney disease or urinary retention * \- History of stroke * \- An ulcer in the past year * \- 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 principal investigator (PI) and/or medical monitor and considered for inclusion * \- History of psychiatric hospitalizations are not exclusionary, but study participation will be determined as per PI's or medical monitor's approval * 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 for illicit drugs at the screening visit (Tetrahydrocannabinol (THC) \& prescribed medications okay) * \- Opioid replacement therapy (including methadone, buprenorphine, or other) * Psychiatric medications * \- Current regular use of any psychiatric medications is exclusionary, with the exception of Selective Serotonin Reuptake Inhibitor (SSRI) and serotonin-norepinephrine reuptake Inhibitor (SNRI) and current evaluation by the PI and/or medical monitor that the participant is otherwise healthy, stable, and able to participate * Medications * \- Use of sympatholytic medications for cardiovascular conditions including hypertension (Example: beta and alpha-blockers) * \- Use of medications that are inducers of nicotine metabolizing enzyme CYP2A6 (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 Other Tobacco Products (OTP) * \- Any of the following products in combination more than 15 times in the past month * \- - smokeless tobacco (snus, oral snuff, chewing tobacco) * \- - pipes * \- - cigars, cigarillos, little cigars * \- - blunts, spliffs * \- - hookah * Other/Misc. Chronic Health Conditions * Fainting (within the last 30 days) * Other "life threatening illnesses" as per PI's or medical monitor's discretion * Pregnancy * \- Pregnancy (self-reported and urine pregnancy test) * \- Breastfeeding (determined by self-report) * Concurrent participation in another clinical trial (at PI's discretion) * Inability to read and write in English * Planning to quit smoking or vaping within the next 60 days * Recent onset or change (worsening) in cough, fever and/or abdominal symptoms (vomiting or pain) in the past two weeks * Diagnosis of pneumonia in the past 3 months * Uncomfortable with blood draws * Known allergy to propylene glycol or vegetable glycerin