The Impact of Chronic E-Cigarette Usage on Microvascular 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