Evaluation of Environmental Emissions From Electronic Cigarettes and Tobacco-Burning Cigarettes

Inclusion Criteria: 1. Able to read, understand, and willing to sign an Informed Consent Form (ICF) and complete questionnaires written in English. 2. Generally healthy males or females, 21 years of age or older at Screening. 3. Able to meet cohort-specific requirements as follows: Cohort 1 - Leading U.S. tobacco-burning non-menthol cigarette, and Cohort 2 - Leading U.S. tobacco-burning menthol cigarette: * self-reports at the Screening Visit smoking at least 5 cigarettes per day and inhaling the smoke, for at least 3 months prior to Screening * self-reports smoking Leading U.S. tobacco-burning non-menthol cigarette or Leading U.S. tobacco-burning menthol cigarette as usual brand (UB) cigarettes \[UB cigarette is defined as the cigarette brand style currently smoked most frequently by the participant\]; Cohort 3 - Electronic cigarette #1 smokers, and Cohort 4 - Electronic cigarette #2 smokers: * self-reports at the Screening Visit smoking a non-menthol e-cigarette at least once per day, for at least 3 months prior to Screening; * willing to switch from using their current e-cigarette brand style to using a different e-cigarette brand style during the study; Cohort 5 - Electronic cigarette #3 smokers: * self-reports at the Screening Visit smoking a menthol e-cigarette at least once per day, for at least 3 months prior to Screening; * willing to switch from using their current e-cigarette brand style to using a different e-cigarette brand style during the study; Cohort 6 - U.S Market-sample electronic cigarette smokers: * self-reports at the Screening Visit smoking the selected U.S. market-sample e-cigarettes (menthol or non-menthol) at least once per day, for at least three months prior to Screening; * willing to continue exclusive use of their preferred style (flavor) of e-cigarette during the study. 4. Females of childbearing potential must be willing to use a form of contraception acceptable to the Investigator from the time of signing informed consent until study discharge or be surgically sterile for at least 90 days prior to enrollment; 5. Able to safely perform the required study procedures, as determined by the Investigator. Exclusion Criteria: 1. Clinically significant or unstable/uncontrolled acute or chronic medical conditions at Screening, as determined by the Investigator, that would preclude a participant from participating safely in the study (e.g., hypertension, asthma, or other lung disease; cardiac disease; neurological disease; or psychiatric disorders) based on screening assessments such as safety labs and medical history or physical examination at Enrollment; 2. Self-reports or safety labs indicate diabetes; 3. At risk for heart disease, as determined by the Investigator; 4. Use of medicine for treatment of depression or asthma; 5. Systolic blood pressure of ≥150 mmHg or a diastolic blood pressure of ≥95 mmHg, measured after being seated for 5 minutes; 6. Postponing a decision to quit smoking (defined as planning a quit attempt within 30 days of the Screening Visit) to participate in this study; 7. Employed by a tobacco company, the study site, or environmental test chamber vendor; 8. Females who have a positive pregnancy test, are pregnant, breastfeeding, or intend to become pregnant during the course of the study; 9. History of claustrophobia; 10. Regularly exposed to solvent fumes or gasoline (e.g., painter, gas-station mini mart employee); 11. Determined by the Investigator to be inappropriate for this study, including a participant who is unable to communicate or unwilling to cooperate with the clinical staff.