Clinical Research Directory

Inclusion Criteria: Adolescent arm: * Aged ≥12 and \<19 years old * Either 1) use neither combustible cigarettes nor e-cigarettes or 2) use e-cigarettes exclusively Adult arm: * Aged ≥19 years old * Fall into one of the following categories: 1) use neither combustible cigarettes nor e-cigarettes; 2) use combustible cigarettes exclusively, never using e-cigarettes; 3) use e-cigarettes exclusively, never using combustible cigarettes; or 4) use both combustible cigarettes and e-cigarettes currently Exclusion Criteria: Adolescent arm: * Contraindication to pulmonary function testing and cardiopulmonary exercise testing * Have smoked combustible cannabis within the last month and/or have a combustible cannabis smoking history of \>1 joint-year * Have smoked combustible cigarettes within the last 6 months * Have a physician-diagnosed chronic lung disease (such as asthma, cystic fibrosis, or bronchopulmonary dysplasia) * Inability to provide written informed consent Adult arm: * Contraindication to pulmonary function testing and cardiopulmonary exercise testing * Have smoked combustible cannabis within the last month and/or have a combustible cannabis smoking history of \>1 joint-year * Currently undergoing treatment for lung cancer * Inability to provide written informed consent No limitations will be placed on the type of e-liquids used by participants; e.g., e-cigarette users of nicotine, tetrahydrocannabinol, and cannabidiol will be all enrolled.