The study is focused on investigating the mechanisms involved in microvascular health in subjects that use e-cigarettes frequently. To explore microvascular health, different techniques and compounds. For one of the tests, iontophoresis, the drug's use will be stored and handled as described by the approved IND and non-IDS plan.

Electronic cigarettes or e-cigarettes have become increasingly popular, due to their promotion as a healthy alternative to traditional tobacco cigarettes. However, there are large discrepancies of knowledge in understanding how these e-cigarettes affect the subjects health and the way their body uses oxygen. The overall goal of this study is to evaluate e-cigarettes usage on subjects health.

e-Cig users arm

Inclusion Criteria:

• Between 18 and 29 years of age
• Used e-cigarettes with nicotine (≥3 times/week for ≥6 months)

Exclusion Criteria:

• 17 years old and younger or 30 years old or older.
• Former combustible tobacco user/ former smoker
• Use of cigarettes for 15 days or more in the past 60 days
• Use of other tobacco products (cigars, hookah, smokeless), marijuana and/or illicit or prescription drugs weekly or more frequently in the past 60 days
• Evidence of cardiovascular, pulmonary, renal, hepatic, metabolic, cerebral diseases or sleep disorders
• Disorder or use of medication that affects cardiopulmonary health
• Evidence of pregnancy or current nursing

Non e-Cig using arm

Inclusion

- Between 18 and 29 years of age

Exclusion

• 17 years old and younger or 30 years old and older
• Use of cigarettes or other tobacco products more than 50 times in their lifetime.
• Evidence of cardiovascular, pulmonary, renal, hepatic, metabolic, cerebral diseases or sleep disorders
• Disorder or use of medication that affects cardiopulmonary health
• Evidence of pregnancy or current nursing

Chronic e-cigs users and never users that are between 18 and 29 years of age.