In this project, after systematically developing electronic nicotine delivery systems (ENDS) pictorial health warning labels (HWLs), a proven clinical lab model will be used to examine and test their effect when these are placed on the ENDS device on a variety of subjective (e.g. satisfaction, harm perception, nicotine dependence, intention to quit) and objective outcomes (e.g. plasma nicotine, puff topography) in young adults.

The use of electronic nicotine delivery systems (ENDS or e-cigarettes) has reached epidemic levels among young people in the United States (US). ENDS emit toxic substances, including nicotine that irreversibly affects youth's developing brain leading to dependence and increased risk of cigarette smoking initiation, yet misperceptions about their safety are widespread. Therefore, health communication of ENDS-related risks through Health Warning Labels (HWLs) has been considered as a priority by leading health and regulatory bodies in the US to reduce ENDS use among young people. The FIU Epidemiology Clinical Tobacco Research Lab has developed and pilot-tested a clinical lab model to examine the potential effects of pictorial HWLs on young (21-29 yrs) ENDS users' experiences. In this proposal, this model, coupled with a systematic development of ENDS pictorial HWLs, will be used to test their effect when they are placed on the device on a variety of subjective (e.g. satisfaction, harm perception, nicotine dependence, intention to quit) and objective outcomes (e.g. plasma nicotine, puff topography). This will be done in three stages. First, the literature will be reviewed to develop candidate messages and their associated pictures for the HWLs. This initial set of HWLs will then be revised and ranked through a Delphi study among tobacco control, regulation, and health communication experts. Second, focus groups with young ENDS (21-29 yrs) users will be conducted to adapt the candidate HWLs to our target population and device itself. Third, HWLs on the ENDS device will be tested in a clinical lab cross-over study, where each subject uses ENDS in 2 sessions; 1) their preferred product without HWL (control), and 2) their preferred product with pictorial HWL on the ENDS device. This design will test our main hypothesis; compared to control, using ENDS with the HWLs is associated with decreased satisfaction, dependence suppression, and puffing behavior, but increased knowledge about harm and intention to quit. This project will guide policymakers into the application of effective HWLs for ENDS and will develop warning messages and pictorials that national and state stakeholders can use through different modalities in counter-marketing campaigns to protect young people and discourage harmful ENDS use.

Inclusion Criteria:

• Generally healthy individuals (determined by physical examination).
• Age of 21-35 years.
• Is willing to provide informed consent.
• Is willing to attend the lab as required by the study protocol.
• ENDS users (defined as using ENDS either daily or occasionally in the past 30 days)
• Have abstained from ENDS use for 12 hours prior to each session.

Exclusion Criteria:

• Report smoking cigarettes regularly (> 5 cigarettes/month in the past year).
• Report regular use of any other tobacco/nicotine product (e.g., e-cig, pipes, cigars) in the past year.
• Women who are breast-feeding or test positive for pregnancy (by urinalysis at screening).
• Individuals with self-reported history of chronic disease or psychiatric conditions.
• Individuals with history of or active cardiovascular disease, low or high blood pressure, seizures, and regular use of prescription medications (other than vitamins or birth control).
• Individuals that report the use of non-commercial (i.e., street) e-cigarette liquid or products
• Individuals that report current EVALI or COVID-19 related symptoms (i.e., cough, shortness of breath, chest pain, nausea, vomiting, abdominal pain, diarrhea, fever, chills, or weight loss)
• Individuals that have or have been exposed to COVID-19 in the last 14 days.