To determine vaping behaviors and respiratory function in obese and nonobese youth e-cigarette users.

The investigators hypothesize that obese youth e-cigarette users will have increased e-cigarette use that will worsen respiratory function. The approach will involve a clinical trial where vaping behaviors (using puff topography) and respiratory function (spirometry, plethysmography, and diffusion capacity) will be assessed while participants vape with their own e-cigarette and, on a separate visit, with the VUSE e-cigarette.

Inclusion Criteria:

• a current e-cigarette user (≥1 vaping bout daily) for at least the past 3 months,
• 21-25 years old,
• willing to abstain from all tobacco and nicotine for at least 12 hours prior to lab sessions,
• willing to complete five lab visits lasting up to 4 hours each,
• able to read and speak English,
• willing to provide informed consent.

Exclusion Criteria:

• self-reported diagnosis of lung disease including asthma or cystic fibrosis
• history of cardiac event or distress within the past 3 months
• history of metabolic disease including thyroid disease or diabetes
• history of orthopedic or neuromuscular problems that preclude exercise
• currently pregnant (determined using urine pregnancy test), planning to become pregnant, delivered a child in the past 6 weeks even if not breastfeeding, or currently breastfeeding
• use of other tobacco products >10 days in the past month
• current marijuana use >10 times per month
• currently engaging in a vaping cessation attempt
• ) competitive athlete or individual currently engaged in an exercise training program involving 420min or more (moderate intensity aerobic activity) or 210 min or more (vigorous intensity aerobic activity) per week with the goal of participating in a competitive event or marathon, triathlon, etc. Participants who are engaged in usual physical activity (e.g., walking dog, biking to work, etc.) but not engaged in a "structured exercise training program" will not be excluded.
• plans to leave the Columbus or central Ohio region within the next year.